Äîêóìåíò âçÿò èç êýøà ïîèñêîâîé ìàøèíû. Àäðåñ îðèãèíàëüíîãî äîêóìåíòà : http://www.naic.edu/~phil/hardware/vertex/doc/orig/om5034.doc Äàòà èçìåíåíèÿ: Thu Sep 25 19:00:38 1997 Äàòà èíäåêñèðîâàíèÿ: Tue Apr 12 13:51:26 2016 Êîäèðîâêà:

ARECIBO OBSERVATORY


SERVO DRIVE SYSTEM UPGRADE





Volume II - Section 1

OPERATION AND MAINTENANCE MANUAL


CONTROL SYSTEMS



Operation, Maintenance and Troubleshooting


Provided for


National Astronomy and Ionosphere Center

Cornell University


Ithaca, NY, USA

Project No. 10/95034

Rev.: 2.2

September 1997







|Vertex Antennentechnik GmbH |Vertex Communications Corporation |
|Baumstr. 50 |2600 Longview Street |
|47198 Duisburg |Kilgore, TX 75663 |
|Germany |U.S.A. |
|Tel. +49-2066-2096-0; Fax -11 |Tel. 903-984-0555; Fax -1826 |
This section of the O&M manual describes the various
components and their arrangement as well as operation,
maintenance and troubleshooting for the control system of the
Arecibo Servo Drive System.

Table of Contents



1. SYSTEM DESCRIPTION 1

1.1 Control System Outline 1

1.2 Description Of Components 3
1.2.1 Programmable Logic Controller (PLC) 3
1.2.2 Drives 7
1.2.2.1 Drive Motors And Motor Controllers 7
1.2.2.2 Drive Control System (DCS) 9
1.2.3 Optical Encoders 11
1.2.4 Drive Cabinet 12
1.2.5 Portable Control Unit (PCU) 13
1.2.6 Limit Switches 14
1.2.7 Time Synchronization 15
1.2.8 Warning Lights and Horns 15

1.3 Definitions 16

2. OPERATION 17

2.1 Operation Overview 17
2.1.1 Control Locations 17
2.1.2 Operating Modes 17

2.2 Power On/Off 18
2.2.1 Preconditions 18
2.2.2 Power Up Procedure 19
2.2.3 Power Down Procedure 19
2.2.4 PLC Status After Power On 19

2.3 Description Of Operating Modes 20
2.3.1 STOP 20
2.3.2 Velocity Command (RATE) 20
2.3.3 Position Command (PRESET) 20
2.3.4 Survival Position (STOW) 21
2.3.5 PROGRAM TRACK 21
2.3.6 Auxiliary Mode 22
2.3.7 Start- and Stop Sequences 23
2.3.7.1 Start Sequence 23
2.3.7.2 Stop Sequence 24

2.4 Selection Of Control Location 25

2.5 Control from Local Control Unit (LCU) and Operation Control Unit
(OCU) 27
2.5.1 Activation 27
2.5.2 Main Menu 27
2.5.3 Selection of a Control Location 29
2.5.4 Activation of an Operating Mode 29
2.5.5 Auxiliary Mode 30
2.5.6 Status Display 31
2.5.7 Failure Display 31
2.5.8 Parameter Menu 31

2.6 Control from Portable Control Unit 32
2.6.1 Activation and Preconditions 32
2.6.2 Axis Selection 33
2.6.3 Axis Activation and Control 33

2.7 Computer Mode (Control by MCS) 34
2.7.1 Activation 34
2.7.2 Commands 34

2.8 Low Level Control from Drive Cabinet 34
2.8.1 Function 34
2.8.2 Activation 34
2.8.3 Operation 35

2.9 Interlocks And Alarms 36
2.9.1 Limit Switches 36
2.9.2 Other Limits 38
2.9.3 Limit Override 40
2.9.4 Failures 40

2.10 Reset 42
2.10.1 Failure Reset 42
2.10.2 PLC Reset 42
2.10.2.1 Restart After Power Down of CPU928 43
2.10.2.2 Manual Warm Restart of CPU928 43
2.10.2.3 Manual Cold Restart of CPU928 43
2.10.2.4 Restart of CP581 44

2.11 Emergency Stop 45

2.12 Special Features 46
2.12.1 Unbending of Feedarm 46
2.12.2 Brake Interlock Detector 46

3. TEST AND TROUBLESHOOTING 47

3.1 Test Outputs 47

3.2 Troubleshooting 49
3.2.1 General Remarks 49
3.2.2 PLC 49
3.2.2.1 CPU 928B 49
3.2.2.2 CP 581 50
3.2.2.3 CP 524 51
3.2.2.4 Digital Output Modules 51
3.2.2.5 Software 51
3.2.3 Faults Indicated on LCU or OCU 52
3.2.3.1 General faults 52
3.2.3.2 Axis Related Failures 54
3.2.4 Unit Failures 56
3.2.4.1 OCU 56
3.2.4.2 PCU 57
3.2.4.3 Optical Encoders 58
3.2.5 Servo Amplifiers 59

3.3 Exchange Of Components 60

4. MAINTENANCE 61

4.1 Regular Maintenance 61
4.1.1 Portable Control Unit 61
4.1.2 PLC RAM Buffer Battery 61
4.1.3 Brakes 61

4.2 Safety during maintenance 62

4.3 Various Maintenance Instructions 62
4.3.1 Precautions During Motor Replacement 62
4.3.2 AUX Mode 63



Updates

Version 2.1 - Aug 97


|page |paragraph |subject |modification |
|10 |1.2.3 |encoder scaling |elevation transmission ratio |
| | | |changed |
|18 |2.3.5 |program track |capacity 127 sets of values |
| | |stack | |
|32 |2.9.1 |travel ranges |new software limits |
|34 |2.9.2 |other limits |new software limits |


Version 2.2 - Sept 97



Page numbers changed with V2.2.


|page |paragraph |subject |modification |
| |1.2.1 |PLC |revised |
| |1.2.2 |drive system |revised |
| |1.2.7 |time |revised; moved here from 2.12. |
| | |synchronization | |
| |1.2.8 |warning lights & |new |
| | |horns | |
| |2.9.2 |limits |softlimits changed |
| |2.3.4 |STOW |stow positions added |
| |2.3.6 |AUX mode |brake interlock override added |
| |2.3.7 |Start/Stop |new |
| | |Sequence | |
| |2.5.5 |AUX activation |brake interlock override added |
| |2.12. |special features |new |
| |4. |maintenance |completely revised |






List Of Abbreviations



AUX Auxiliary Mode

AZ Azimuth

BCD Binary Coded Decimal

CH Carriage House #1

CPU Central Processing Unit

DPRAM Dual Port Random Access Memory

GD Gregorian Dome

HU Height Unit (1 HU = 1.75 inches)

IRIG InterRange Instrumentation Group

LAN Local Area Network

LCD Liquid Crystal Display

LCU Local Control Unit

LED Light Emitting Diode

LSB Least significant bit

MCS Monitoring & Control System (host computer)

OCU Operation Control Unit

PCU Portable Control Unit

PLC Programmable Logic Controller

PWM Pulse Width Modulated

RF Radio Frequency

UPS Uninterruptable Power Supply





1 System Description


1.1 CONTROL SYSTEM OUTLINE


Control and supervision of the Arecibo Servo Drive System is handled by the
control system. Positions, status and commands are monitored, drives and
signals will be controlled accordingly.

The block diagram on the next page shows the main components of the control
system and their arrangement.

The main components are:

- Drive Cabinet with


Power supplies

Programmable Logic Controller

Local Control Unit (LCU) with Keyboard

Servo Amplifiers

Drive Control System

Circuit Breakers and Interlock System

- Uninterruptable Power Supply
- Motors
- Optical Encoders
- Limit Switches
- Portable Control Unit (PCU)
- Operation Control Unit (OCU).


The PLC is the center of the system which coordinates all actions,
monitoring of signals and calculations in every mode. Moreover, the PLC
interfaces to the host computer via a LAN interface. In "Computer" mode the
host computer is allowed to operate the drives. (A detailed description of
this LAN interface can be found in section 2 of this manual.)

In addition to this the drives can be controlled from the Local Control
Unit (located inside switch cabinet 3), from the Operation Control Unit in
the Control Room and from the Portable Control Unit.

In all axes, the Arecibo Servo Drive System is equipped with antibacklash
drive control. The drive system also ensures torque equalization between
the individual trucks (for azimuth) or trolleys (for elevaton). The motors
are fed by transistorized servo amplifiers. The actual positions are
measured by absolute optical multi-turn encoders.

Blockdiagramm - BS5034.SKD



1.2 Description Of Components


1.2.1 Programmable Logic Controller (PLC)


The main tasks of the PLC are

- Position control of azimuth, elevation and CH#1
- Communication to host computer (MCS)
- Communication to the operating stations (OCU, LCU)
- Communication to Portable Control Unit
- Output of rate setpoints to the Drive Control System
- Prevention of inadmissible operating states.

The PLC, type SIMATIC S5-135U, is perfectly designed for industrial process
control applications. The SIMATIC S5 is widespread in the industry and has
set up the standard for many other manufacturers. Its comprehensive
interface system meets the requirements of process automation particularly
well. All interfaces are handled by individual microprocessor plug-in
units. A serial link connects the Portable Control Unit to the PLC. An
additional 386 "plug-in PC" is responsible for the communication to the
host computer (LAN interface), to the Operation Control Unit (OCU) in the
Control Room and to the monitor and keyboard which comprise the Local
Control Unit.

The CP581 is an AT-compatible PC, equipped with 4 MByte main memory, a
silicon disk and interfaces for printer, monitor, keyboard and serial
interfaces. It can be plugged into the S5-135U and has a direct connection
to the CPU via the S5 bus. This allows the CPU to concentrate on mere
control tasks which are closely related to the drive system while the CP581
handles more peripheral tasks like operator interfaces, time
synchronization etc. The CP581 is extended by two AT slots. These are used
for the LAN interface board (for TCP/IP transmission protocol) and an IRIG-
B time code reader.

The position loop is closed digitally inside the PLC considering the
position setpoints (from operator or calculated from a commanded tracking
pass) and the actual position feedbacks from the axis encoders. The
position loop outputs are analog velocity setpoints (one per axis), which
are fed to the Drive Control System (cf. page 9).

The actual states of all in- and outputs of the PLC are displayed by LEDs
at the respective input and output modules. All digital inputs and outputs
are optically isolated, and all analog inputs and outputs galvanically
isolated. All input and output modules have plastic covers to protect the
components and printed circuits against accidental contact.

The central controller consists of a compact housing with power supply
chassis, fans and battery compartment (for buffering the RAM) and 21 module
slots. The expansion unit is similarly arranged but does not have a power
supply included. The central controller and the expansion unit are
connected via two interface modules and a communication cable.

The input voltage is 240 or 115 V AC, selectable at the PLC front panel.
The power supplies provide all voltages which are internally necessary for
all modules (+5V,+24V) short-circuit proved. The power supply chassis can
be replaced by removing two screws.

Layout of the PLC




çäääääääääääääääääääääääääääääääääääääääääääääääääääääää¿

¨ çää¿ çää¿ ¨

¨ þääû þääû ¨

çäääääääåääääääääääääääääääääääääääääääääääääääääääääääääääääáää´

¨ ¨ ¨ ¨

¨ öääääääääääääääääääääääääääääääääääääääääääääääääääää´ ¨

¨ ¨ 6ES5 928B-3UB11 Main CPU çääääääääääääää¿ ¨ ¨

¨ ¨ ¨ EPROM ¨ ¨ ¨

¨ ¨ þääääääääääääääû ¨ ¨

¨ öääääääääääääääääääääääääääääääääääääääääääääääääääää´ ¨

¨ P ¨ ¨ ¨

¨ öääääääääääääääääääääääääääääääääääääääääääääääääääää´ ¨

¨ O ¨ ¨ ¨

¨ öääääääääääääääääääääääääääääääääääääääääääääääääääää´ ¨

¨ W ¨ ¨ ¨

¨ öääääääääääääääääääääääääääääääääääääääääääääääääääää´ ¨

¨ E ¨ 6ES5 581-1EA11 CP581 (PC 386) ¨ ¨

¨ ö----------------------------------------------------´ ¨

¨ R ¨ ORA11 Slot Module- LAN Interface - ¨ ¨

¨ ö----------------------------------------------------´ ¨

¨ ¨ ORA11 Slot Module- Time Code Reader - ¨ ¨

¨ S öääääääääääääääääääàäääääääääääääääääääääääääääääääää´ ¨

¨ ¨ ¨ ¨

¨ U öääääääääääääääääääääääääääääääääääääääääääääääääääää´ ¨

¨ ¨ 6ES5 524-3UA13 Serial Interface 01D01¨ ¨

¨ P öääääääääääääääääääääääääääääääääääääääääääääääääääää´ ¨

¨ ¨ 6FM1 705-3AA00 SSI Encoder Interface 22D03¨ ¨

¨ P öääääääääääääääääääääääääääääääääääääääääääääääääääää´ ¨

¨ ¨ ¨ ¨

¨ L öääääääääääääääääääääääääääääääääääääääääääääääääääää´ ¨

¨ ¨ ¨ ¨

¨ Y öääääääääääääääääääääääääääääääääääääääääääääääääääää´ ¨

¨ ¨ 6ES5 465-4UA12 Analog Input, addr.128, label 55D01¨ ¨

¨ / öääääääääääääääääääääääääääääääääääääääääääääääääääää´ ¨

¨ ¨ 6ES5 465-4UA12 Analog Input, addr.160, label 57D01¨ ¨

¨ F öääääääääääääääääääääääääääääääääääääääääääääääääääää´ ¨

¨ ¨ ¨ ¨

¨ A öääääääääääääääääääääääääääääääääääääääääääääääääääää´ ¨

¨ ¨ 6ES5 470-4UB12 Analog Output, add.224, label 59D01¨ ¨

¨ N öääääääääääääääääääääääääääääääääääääääääääääääääääää´ ¨

¨ ¨ 6ES5 470-4UB12 Analog Output, add.240, label 60D01¨ ¨

¨ öääääääääääääääääääääääääääääääääääääääääääääääääääää´ ¨

¨ ¨ ¨ ¨

¨ öääääääääääääääääääääääääääääääääääääääääääääääääääää´ ¨

¨ ¨ 6ES5 300-5CA11 EU Interface Module ¨ ¨

þäääääääåääääääääääääääääääääääääääääääääääääääääääääääääääääàää´

¨ çää¿ çää¿ ¨

¨ þääû þääû ¨

þäääääääääääääääääääääääääääääääääääääääääääääääääääääääû

Layout of the PLC (cont'd)




çääääääääääääääääääääääääääääääääääääääääääääääääääääää¿

¨ çää¿ çää¿ ¨

¨ þääû þääû ¨

çäääääääåäääääääääääääääääääääääääääääääääääääääääääääääääääáää´

¨ ¨ 6ES5 430-4UA12 32 Bit Input, addr.0, label 07D01¨ ¨

¨ öäääääääääääääääääääääääääääääääääääääääääääääääääää´ ¨

¨ ¨ 6ES5 430-4UA12 32 Bit Input, addr.4, label 11D01¨ ¨

¨ öäääääääääääääääääääääääääääääääääääääääääääääääääää´ ¨

¨ ¨ 6ES5 430-4UA12 32 Bit Input, addr.8, label 15D01¨ ¨

¨ öäääääääääääääääääääääääääääääääääääääääääääääääääää´ ¨

¨ ¨ 6ES5 430-4UA12 32 Bit Input, addr.12, label 19D01¨ ¨

¨ öäääääääääääääääääääääääääääääääääääääääääääääääääää´ ¨

¨ ¨ 6ES5 430-4UA12 32 Bit Input, addr.16, label 23D01¨ ¨

¨ öäääääääääääääääääääääääääääääääääääääääääääääääääää´ ¨

¨ ¨ ¨ ¨

¨ öäääääääääääääääääääääääääääääääääääääääääääääääääää´ ¨

¨ ¨ ¨ ¨

¨ F öäääääääääääääääääääääääääääääääääääääääääääääääääää´ ¨

¨ ¨ ¨ ¨

¨ A öäääääääääääääääääääääääääääääääääääääääääääääääääää´ ¨

¨ ¨ ¨ ¨

¨ N öäääääääääääääääääääääääääääääääääääääääääääääääääää´ ¨

¨ ¨ ¨ ¨

¨ öäääääääääääääääääääääääääääääääääääääääääääääääääää´ ¨

¨ ¨ ¨ ¨

¨ öäääääääääääääääääääääääääääääääääääääääääääääääääää´ ¨

¨ ¨ ¨ ¨

¨ öäääääääääääääääääääääääääääääääääääääääääääääääääää´ ¨

¨ ¨ 6ES5 451-4UA12 32 Bit Output, addr.0, label 27D01¨ ¨

¨ öäääääääääääääääääääääääääääääääääääääääääääääääääää´ ¨

¨ ¨ 6ES5 451-4UA12 32 Bit Output, addr.4, label 31D01¨ ¨

¨ öäääääääääääääääääääääääääääääääääääääääääääääääääää´ ¨

¨ ¨ 6ES5 451-4UA12 32 Bit Output, addr.8, label 35D01¨ ¨

¨ öäääääääääääääääääääääääääääääääääääääääääääääääääää´ ¨

¨ ¨ 6ES5 451-4UA12 32 Bit Output, addr.12,label 39D01¨ ¨

¨ öäääääääääääääääääääääääääääääääääääääääääääääääääää´ ¨

¨ ¨ 6ES5 451-4UA12 32 Bit Output, addr.16,label 43D01¨ ¨

¨ öäääääääääääääääääääääääääääääääääääääääääääääääääää´ ¨

¨ ¨ ¨ ¨

¨ öäääääääääääääääääääääääääääääääääääääääääääääääääää´ ¨

¨ ¨ ¨ ¨

¨ öäääääääääääääääääääääääääääääääääääääääääääääääääää´ ¨

¨ ¨ ¨ ¨

¨ öäääääääääääääääääääääääääääääääääääääääääääääääääää´ ¨

¨ ¨ 6ES5 312-5CA11 CU Interface Module ¨ ¨

þäääääääåäääääääääääääääääääääääääääääääääääääääääääääääääääàää´

¨ çää¿ çää¿ ¨

¨ þääû þääû ¨

þääääääääääääääääääääääääääääääääääääääääääääääääääääääû




1.2.2 Drives


1.2.2.1 Drive Motors And Motor Controllers


Azimuth and Gregorian Dome axes are each equipped with 8 AC servo motors.
The Carriage House #1 axis has two motors of the same type as used for the
Gregorian Dome.

The Kollmorgen motors are brushless servomotors with sine wave communtation
and integrated frameless resolvers. The resolvers are used for electronic
commutation and velocity feedback. The Kollmorgen BDS4A amplifiers combine
microprocessor control with an integrated PWM servo amplifier resulting in
precise torque and velocity control. The three-phase sinusoidal current
waveform provides smooth, efficient motor operation. The amplifier converts
the resolver feedback into an actual velocity signal.

The current loop is closed inside the servo amplifiers. The amplifiers
provide the currents needed for operating the drive motors and an analog
velocity feedback output. Inputs to the servo amplifiers are the (analog)
current setpoints supplied by the Drive Control System (cf. page 9). Each
motor is connected to one amplifier. The amplifiers in return provide an
analog velocity monitor that is fed to the DCS for use in the velocity
loop.

An electromagnetic brake is integrated in each motor. Operating in Power
Off/Brake Engaged mode, the brake provides 35 lbft (48 Nm) of torque for
static parking and emergency braking. The brake function is supervised by
brake current monitor relays in the drive cabinet.

Protection class of the motors is IP67, ensuring full protection against
contact with live parts, protection against ingress of water and full
protection against ingress of dust. In order to protect the motors against
internal condensation and corrosion because of the high humidity of the
air, the motors will be heated during standstill using the main winding. A
breath hole at the bottom side allows for the necessary exchange of air.

Details about the motor rating and performance can be found in the table on
the following page.

Drive Performance

| |Azimuth |Gregorian |Carriage |Dim. |
| | |Dome |House | |
|Max. windspeed |50,00 |50,00 |50,00 |mph |
|Max. velocity of the |0,417 |0,042 |0,042 |degr/s|
|antenna | | | | |
|Max. accel. of the antenna|0,100 |0,025 |0,025 |degr/s|
| | | | |� |
|Motor type |B604-A |B606-A |B606-A | |
|Max. motor speed |2002 |1269 |1269 |rpm |
|Overall transmission ratio|28.827 |182.671 |182.671 | |
|Gear box transmission |163,550 |190,070 |190,070 | |
|ratio | | | | |
|Number of motors |8 |8 |2 | |
|Moment of inertia per |0,002161 |0,003167 |0,003167 |kgm� |
|motor | | | | |
|Number of gear boxes |8 |8 |2 | |
|Mom. of inert. per gear |0,003 |0,0045 |0,0045 |kgm� |
|box | | | | |
|Max. torque per motor |17,97 |37,56 |28,06 |Nm |
|Nom. torque per motor |15,25 |36,44 |27,40 |Nm |
|(without acc.) | | | | |
|rated torque motor, n=0 |30,10 |44,80 |44,80 |Nm |
|rated torque motor, nmax |26,00 |41,00 |41,00 |Nm |
|max. motor torque n=0/nmax|86,00 |131,90 |131,90 |Nm |
|max. motor torque |63,36 |89,56 |89,56 |Nm |
|available | | | | |
|Motor torque constant |1,584 |2,239 |2,239 |Nm/A |
|Motor voltage constant |0,914 |1,293 |1,293 |Vs/rad|
|Maximum current per motor |11,3 |16,8 |12,5 |A |
|Maximum voltage per motor |203,4 |196,1 |190,0 |V |
|Maximum power per motor |4,00 |5,70 |4,12 |kW |
|Nom. power per motor |3,39 |5,53 |4,03 |kW |
|(without acc.) | | | | |
|Max. overall power per |31,99 |45,59 |8,25 |kW |
|axis | | | | |
|Type of Servo Amplifier |BDS4A-220H |BDS4A-220H |BDS4A-220H | |
|Servo control range |1:1000 |1:1000 |1:1000 | |
|Peak current amplifier |40 |40 |40 |A |
|Continuous Current |20 |20 |20 |A |
|amplifier | | | | |
|max. power regeneration |8,58 |29,49 |5,55 |kW |


1.2.2.2 Drive Control System (DCS)


The Drive Control System (DCS) performs all drive control tasks which are
specifically required for the motor arrangement at Arecibo Observatory,
including

- velocity loops
- difference velocity control
- torque biassing
- torque equalization
- gravity compensation.

All circuits a set up as analog control circuits. Inputs to the DCS are

- analog velocity setpoint (from PLC), one signal per axis
- analog actual velocities (from servo amplifiers), one signal per
motor
- analog gravity compensation input (from PLC), one signal per axis;
GD/CH only
- analog torque bias input (from PLC), one signal per axis; GD/CH
only
- analog bending compensation input (from PLC), one signal per axis;
Az only

The outputs from the DCS are the analog torque commands to the servo
amplifiers (one per motor).

In addition, the DCS provides a possibility to operate the drives at a very
low level in the chain of control. Each axis can be operated separately in
jog mode by forward/reverse pushbuttons. The speed can be selected by a
potentiometer.

The DCS includes a separate 19" 4HU rack mounted unit for each axis. It
comprises

- power supply

- analog printed circuit boards for


. acceleration limiter

. differential velocity control

. velocity loop

. torque bias

. zero speed detection

. tacho failure detection

- pushbuttons and potentiometers for low level operation.

- displays for actual velocity and torque.

A front view of the DCS is shown on the following page.

Frontansicht DCS


(aus DCS Dokumentation)

1.2.3 Optical Encoders


The actual positions are measured by absolute optical mult-turn encoders.
There are two encoders for azimuth, one for the Gregorian Dome and one for
Carriage House #1.

The two azimuth encoders are placed at opposing ends of the feed arm. The
real Az position is measured by the encoder on the Gregorian side only. The
CH1 side encoder is used to measure any bending of the feed arm and to
check for any drastic discrepancies in the readings of the two encoders. In
case of failure of the Gregorian side encoder the CH1 side encoder is used
for determination of the present Az position. This implies a reduced
overall accuracy.

Technical data of the encoders:

Manufacturer TR Electronic

Type CE-65-M

No. of revolutions 4096

Resolution per rev. 4096

Accuracy ± 0.2 LSB

Supply voltage 11 ... 27 VDC

Data interface SSI (synchr.-serial), TTL level

Class of protection IP65

Temperature range 0 ... 60 œC (32 ... 140 F)

Code Gray

Encoder resolution:


| | | |Azimuth |Elevation |
| | | | |[1] |
|travel distance |stot| |730œ |20œ |
|rack diameter |d1 | |127 ft |840,9375 |
| | | | |ft |
|pinion diameter |d2 | |2.5 in |9.5 in |
|transmission ratio |i1 |= d1 / d2 |609.6 |1062.24 |
|resolution per encoder |N1 | |4096 |4096 |
|rev. | | | | |
|overall resolution |ds |= 360œ / i1 / |0.000144œ |0.0000827œ|
| | |N1 |(0.519 | |
| | | |arcsec) |(0.282 |
| | | | |arcsec) |
|no. of encoder |N2 |= stot /360œ |1236 |62 |
|revolutions | |* i1 | | |

The encoders interface directly to the encoder input module of the PLC.

1.2.4 Drive Cabinet


The servo equipment is integrated in a drive cabinet in the electronics
shelter on the feed arm. The cabinet consists of three units ith a width of
1200 mm each.

Cabinet 1:

- Azimuth servo amplifiers

- Carriage House servo amplifiers

- main switch and incoming circuit breakers / fuses

- Az and CH contactors and breakers

- uninterruptable power supply

Cabinet 2:

- Gregorian Dome servo amplifiers

- power supplies for auxiliary voltages

- GD contactors and breakers

- brake current and DC bus monitoring relays (all axes)

- regeneration rack (all axes)

Cabinet 3 (Control Rack):

- Programmable Logic Controller

- Drive Control Systems

- Local Control Unit (monitor & keyboard)

- coupling relays.

Additional regeneration resistor assemblies and an isolation transformer
for the drive power are installed outside the electronics shelter.

Surge arrestors are connected to the incoming power terminals in order to
remove voltage peaks caused by EMI or lightning. Additional arrestors and
filters are connected to each secondary voltage (such as 230 V 3ph. for the
drives, 28 VDC for the brakes etc.) and to all electronics equipment. In
addition to this the level of the incoming voltage is checked by a voltage
supervision relay. Should the mains voltage leave the specified range of
480 V ± 10%, the drive power will be switched off and an alarm reported to
the MCS.

The uninterruptable 120 VAC power supply located in the leftmost cabinet
provides power for the PLC in case of mains failure. This ensures reporting
of status to the MCS.

On the door of the drive power rack there is the Power On switch and the
Emergeny Off pushbutton. In order to ensure optimum RF shielding, the
cabinet doors should remain closed during normal operation. The Local
Control Unit allows for full operation on a local level. For details see
page 27.

1.2.5 Portable Control Unit (PCU)


The Portable Control Unit is a hand held outdoor unit which allows the
manual control of each drive at the structure. A LCD-display shows the
actual position of one axis and the corresponding (sum) current monitor
information. A pushbutton scrolls through the various axes. A rate command
potentiometer allows manual rate control of the corresponding drive units.
Failure and status messages are indicated by a set of LEDs. The PCU
connector may be plugged into one (of four) PCU connection boxes.

In order to be compact and lightweight, the PCU contains status and
controls for only one axis. The operator may select and control any axis at
any of the PCU interface boxes, however, only one axis can be controlled at
a time.

PCU2.DXF

[pic]

1.2.6 Limit Switches


A system of limit-switches automatically prevents inadmissible operating
states.

For GD and CH, one rotary cam limit switch each is used for prelimits and
operating limits. Each cam switch has six cams which can be adjusted
separately. Separate lever actuated limit switches are installed for the
emergency limits and for the collision protection.

For function of these switches see page 36.



1.2.7 Time Synchronization


The CP581 (plug-in PC in the PLC) is equipped with an IRIG-B time code
reader.

This real time clock module is able to receive, demodulate and decode a
serial IRIG-B time code amplitude modulated either to a carrier of 1kHz
(standard) or 5Mhz. From the input signal it extracts both time of day and
the 1 pps 'on time' pulse. The on board oscillator allows for subsecond
time on microsecond basis.

Both CP581 and CPU928 will use the time transferred by the Time Code
Reader. The IRIG-B time is transferred every second from CP581 to CPU928.
The transfer will always be performed immediately after reading the IRIG-B
board; therefore the transmission delay is constant. Between transmissions
and if this source fails, the CPU will use its internal interrupt driven
clock which has a resolution of 10ms.

IRIG-B Time Code Reader Technical Data:

type BANCOMM bc630AT

time code used IRIG-B 1 kHz

accuracy 150 µs

connector for time code input RJ11



1.2.8 Warning Lights and Horns


Each axis is equipped with warning lights and one warning horn. After a
move request the horn is sounded for several seconds before the axis will
start to move. The warninglights will be turned on as long as the axis is
enabled and the brakes released.

Attention!


Even an axis that is obviously not moving may take off at any time
without sounding the horn, as long as the warning lights are on! The
axis might be "sitting" at a fix position and waiting for the next
position command!

The sounds of the warning lights can be adjusted with a switch after
removing the horn housing.



1.3 Definitions


Axis directions:

Azimuth: 0œ = feedarm in north-south direction

CH in the north, GD in the south


movement in positive direction when feedarm is rotating

clockwise, looking on the feedarm from above

Gregorian Dome 0œ is in the center (lower) position


movement in positive direction when moving up to the GD
side

Carriage House #1 0œ is in the center (lower) position


movement in positive direction when moving up to the CH
side

2 Operation


2.1 OPERATION OVERVIEW


2.1.1 Control Locations


The telescope can be operated from four different locations:

- Portable Control Unit (PCU), pluggable at four locations:


. at either side of the feed arm

. on top of the Gregorian Dome central to the elevation drives

. at CH1 near the drive unit

- Local Control Unit, LCU (in the drive cabinet on the platform)

- Operation Control Unit, OCU (main control room)

- MCS (host computer) via remote (LAN) interface.

The control location can be selected for each axis separately.

In case of OCU, LCU and LAN failure there is an additional possibility to
operate the drives in jog mode from the Drive Control System inside the
control rack.


2.1.2 Operating Modes


The following operating modes are available:

- RATE Movement at constant velocity

- PRESET Movement to a predefined position

- STOW Movement to a predefined survival position with
subsequent STOP

- PROGRAM TRACK The positioner axes track desired trajectories
whose samples have been transmitted from the host
computer via the LAN-Interface

All modes can be activated separately for Azimuth, Gregorian Dome and
Carriage House.

RATE is available at all of the control locations, PRESET (including STOW)
is available from the LCU, OCU and via LAN interface, PROGRAM TRACK can
only be activated by the host computer (MCS).



2.2 Power On/Off


2.2.1 Preconditions


To prepare for operation the drive cabinet must be fed with

480 V three phase power, 60 Hz.

If the mains voltage is outside the allowable range of ±10% for more than
200 ms, the drive power will be switched off, which will cause an emergency
stop for all axes in motion. A voltage failure has to be acknowledged by
the operator. There is a minimum delay of 5 s before power can be turned on
again.

The power for the PLC is supplied by a UPS System in order to maintain the
status information for approx. 15 minutes after a mains power failure.
However, no control is possible in case of a power failure. In addition, a
lot of "false" failure messages will occur because the 24V DC for the PLC
inputs are not connected to the no break power supply. The UPS is connected
to the 120 VAC control voltage which is generated inside the drive cabinet.

The main switch +PD-20CI01 in drive cabinet 1 must be switched on to power
up the drive cabinet. Circuit breakers +PD-21OL01, -21OL02, and -21OL03
must be switched on for the control voltages. These breakers are located in
cabinet 1.

For the individual axes the following circuit breakers must be switched on:

Azimuth +AZ - 1 OL 01, +AZ - 1 OL 02 in cabinet 1

Gregorian Dome +GD - 1 OL 01, +GD - 1 OL 02 in cabinet 2

Carriage House +CH - 1 OL 01 in cabinet 1.

As a minimum, the following fuses have to be switched on:

Normally all automatic fuses in cabinet 3 must also be switched on. As a
minimum, fuses +PD-22FU03, +PD-22FU04, +PD-22FU05, +PD-22FU06, +PD-22FU07,
+PD-22FU08, +PD-232FU03,+PD-26FU01, +PD-26FU02 and +PD-26FU03 must be
switched on. For a description of the function of these fuses and circuit
breakers see Vol. II (Installation Manual), section circuit diagrams.

The DCS units must also be turned on for operation of a particular axis.
The power switches are located on the rear side of the DCS enclosures in
cabinet 3.


2.2.2 Power Up Procedure


Assuming that all breakers, fuses etc. are switched on, only the main
switch +PD-20CI01 in drive cabinet 1 must be switched on to power up the
drive cabinet.

After power-up, the pushbutton "Power On" at the door of cabinet 1 has to
be pressed. Power on requires all emergency stop pushbuttons to be
released.

After each emergency stop the power must be switched on again (cf. page
44).

The complete power up procedure including start-ups of all related
computers takes approx. 60 seconds.


2.2.3 Power Down Procedure


No particular sequence of actions has to be observed. For powering down the
whole cabinet only the main switch +PD-20CI01 in drive cabinet 1 must be
switched off. An axis can be disconnected from the mains by switching off
the related circuit breakers (cf. previous page). Individual units can be
switched off for maintenance purposes by tripping the resp. automatic
fuse(s).


2.2.4 PLC Status After Power On


After powering up the PLC the status is as follows:

- green LEDs "RUN" on CPU and CP581 must light;

red LEDs on CPU, CP581 and CP524 must be off

- main power off (unless "Power On" pushbutton has already been
pressed)

- all axes in previous (before power down) control mode

- all axes in Stop mode

- all LCU/OCU/MCS commands reset

- limits, loop parameters, timers etc. as before power down



2.3 Description Of Operating Modes


2.3.1 STOP


In this mode the brakes are applied, the controllers and servo amplifiers
are disabled. The control system is ready to be switched over to any other
mode. When changing to the STOP mode during movement of the corresponding
axis, a stop sequence first takes place:

The nominal slew value is set to zero, the axis involved being electrically
braked, guided on the ramp of an acceleration limiter. This limiter resides
redundantly in the software and as analog circuit in the DCS. On axis
standstill, the brakes are engaged and the motor currents supplied by the
servo amplifiers are switched off.

The STOP mode can be initiated separately for each axis. Many of the
possible fault conditions result in activation of the STOP mode.



2.3.2 Velocity Command (RATE)


The selected axis moves with a constant velocity which is defined by the
user via a keyboard entry at LCU or OCU, by potentiometer at the PCU or via
the remote interface. The movement is stopped either by a STOP command or
by reaching a motion limit.

During RATE the position loop is not active. Only the velocity loop will be
closed. Torque bias and torque equalization will be active.



2.3.3 Position Command (PRESET)


Any position in the range of an axis can be set. The axis moves with
maximum speed and acceleration to the selected position. It does not drift
away from this position because position control remains active.

Entering or sending a new position before reaching the previous one will
automatically cancel the old command. The axis will move to the new
position.



2.3.4 Survival Position (STOW)


The axis move to a fixed survival position. After reaching this survival
position stop mode will be activated automatically.

Stow Positions:

Azimuth 437.8783 degr

Gregorian Dome 8.4684 degr

Carriage House 8.8348 degr

The stow positions are fixed in the Eprom of the PLC. To modify the stow
positions the DB151 (DD170ff) has to be modified offline with a Step5
development system. After this a new Eprom has to be blown. The stow
positions are entered as integer multiples of 10-4 degr and have to be
converted to hex.



2.3.5 PROGRAM TRACK


A predefined path will be tracked. The path will be determined by time
tagged position commands (Az/GD/CH/t samples), which will be transferred in
advance by the host computer. Program Track is therefore available from the
MCS only.

The samples may be sent asynchronously. They are stored in a stack register
with a capacity of 127 sets of values. The PLC causes the axes to reach the
given positions at the respective time. Between two successive positions a
linear interpolation is done.

A clear stack command from the host computer will clear the whole stack in
the PLC.

The Program Track mode can be activated for one, two or three axes. The
position/time samples are valid for all axes in Program Track.

Further characteristics of Program Track:

- Before sending data for a new path a clear stack command must be
sent. This does not apply if the system is already in Program Track.

- Time tags must be transferred in "milliseconds of day".

- Crossing Midnight is permitted. There is no ambiguity when
crossing midnight.

- The system will move in Preset to the first Program Track
position. If the time to go there is not sufficient, an automatic
switchover to Program Track will take place.

- The position/time samples have to be transmitted in the order they
have to be tracked. They will not be sorted by the PLC.

- The time difference between two subsequent samples must not exceed
12 hours. If so, the time would be interpreted as being in the past.

- If during Program Track a sample with a time tag in the past is
detected this sample will be disregarded. The next sample with a valid
time tag will be used instead.

- If there is no more valid sample the axis will keep its current
position with drives remaining switched on.

- If position samples are transmitted that do not contain position
values for all the axes in Program Track the axes without valid
commanded position will keep its present position.

- If the next commanded position cannot be reached in time even with
maximum speed the axis tries to catch up with the commanded path as
soon as possible. This may lead to oscillations in some cases.


2.3.6 Auxiliary Mode


(This is not an operating mode like Preset etc. as described above but a
status of a particular axis).

In case of motor or amplifier failure each axis can be operated in
auxiliary (AUX) mode with reduced performance. The AUX mode has to be
enabled at LCU, OCU or by the MCS. Without AUX mode the whole axis would be
not operational with one motor or amplifier in faulty condition. In AUX
mode all operating modes described above are available.

AUX mode requires the "Brake Interlock Override" switch to be activated.

Consequences of AUX mode:

Azimuth:

- The azimuth axis will be operated with four motors only (one pair
of motors at one side of the trolley on both ends of the feed arm).


Torque equalization between the two sides of the feed arm will be
maintained.

- This means that AUX mode has to be enabled for a particular side
(front or rear).

- The torque bias will be switched off.

Gregorian Dome / Carriage House:

- The AUX mode has to be enabled for a particular amplifier and
motor.

- The remaining motor of that truck will operate in no bias mode.

- The axis will operate with seven motors instead of eight.

- Only one motor may be switched off. Enabling AUX mode for more
than one motor will result in axis stop. Further operation will be
inhibited.

The motor heating during standstill which will prevent ingress of moisture
into the motors is turned off for the disabled motor(s). Please observe
maintenance recommendations in par. 4.3.2.



2.3.7 Start- and Stop Sequences


Independent from a particular operating mode, the start and stop sequences
for a drive always follow the same pattern.

2.3.7.1 Start Sequence


The start sequence is initiated only if all preconditions for operating
that particular axis have been fulfilled. Such preconditions are:

- control voltages ok
- brake voltage ok
- no cabinet overtemperature
- no emergency off
- mains voltage inside allowed range
- position evaluation system working
- axis not in emergency limit
- no pending axis failure.

If all these conditions are met, the start sequence will be initiated
immediately after a move request from the acrive control location.

Sequence of activities, one step at a time:

- sound warning horn, switch on warning light
- after 5 sec: switch off warning horn
- switch on main contactor(s) - if not yet done; allow 500 ms for
power-up of DC bus
- enable amplifiers, apply gravity compensation (GD, CH), velocity
setpoint zero
- after 0.5 sec: open brakes
- wait for "brake open": all brakes commanded to be released,
feedback of all brake current relays
- after "brake open" feedback: apply velocity setpoint
- acceleration along software ramp until requested velocity has been
reached.


2.3.7.2 Stop Sequence


There are two ways of stopping an axis in motion: a controlled "soft" stop
with deceleration to zero speed and subsequent brake engagement or a sudden
stop with immediately setting the brakes.

a) Controlled Stop

A soft stop is initiated on three occasions:

- no more move request from the active control location
- a failure has occurred the nature of which allows a controlled
stop
- the conditions required for moving an axis (cf. previous section)
are no more fulfilled.

A controlled stop is performed following this sequence:

- set velocity setpoint to zero
- deceleration along the software ramp
- wait for "speed zero" signal (derived from amplifier velocity
monitors)
- after speed zero signal has been detected

(or after the maximum theorectical deceleration time at the latest):

remoce brake release commands
- wait for "brakes closed": all brake release commands removed, no
more feedback from current relays, plus an additional allowance for
real closing of the brakes (300 ms).
- disable amplifiers
- axis is now in Stop mode.


a) Sudden Stop

A sudden stop will immediately set the brakes, either caused by the
interlock system (PLC or hardware) or because the drive and brake power has
failed. The amplifiers will be switched off after the brakes have been
closed (cf. controlled stop).

A sudden stop will occur after the following occasions:

- emergency stop
- emergency limit
- control voltage failure
- mains voltage out of range
- axis power supply failure
- "local axis disable" switch activated.





2.4 Selection Of Control Location


The control location normally is selected by softkeys on the keyboard of
the device in control. For explanation of these softkeys see page 27. The
actual control location is displayed on the screen.

Interlocks and Switchover Conditions:

The following definitions and limitations apply for the individual control
locations:

- The default mode after PLC reset or initial power up is OCU
control. After power failure and power up the previous control mode(s)
will be active again.

- LCU control has overriding privilege over all other locations,
i.e. LCU can take control at any time.

- Once LCU control has been activated, the LCU must hand control
back to OCU or MCS.

The PCU will also take control at any time after the resp. axis is
activated at the PCU (see page 32). The PCU requests control for one
axis only. The others remain unchanged.


Once PCU control has been activated for a particular axis, the PCU must
give control back before any other control location can get control
again.

- MCS and OCU can take or receive control from each other at any
time without further restrictions. Swapping of control between OCU and
MCS does not invoke a change of operating mode.

- An "All/Local Only" switch on the drive cabinet for each axis
limits the choice of control locations to LCU and PCU if set to "Local
Only". When set back to "All", the control stays where it is.

- In case of LAN Interface failure the command will be given to the
OCU. The axis stays in the previous mode.

Preconditions for any control mode:

- power on (cf. page 18)
- no emergency stop condition
- all PLC modules operational (internal check)

In addition to these general requirements for operation there may be
additional conditions for certain control modes.

Additional requirements for PCU mode:

- faultless communication with PCU (after plug-in only)

Additional requirements for LCU / OCU / MCS mode:

- PLC internal interface CPU928 -CP581 working correctly

Additional requirements for MCS mode:

- LAN interface between CP581 and MCS working correctly

If the conditions for the selected control mode are not fulfilled the
selection is not accepted. The control mode is not changed.

Any switch-over between control modes automatically cancels all previous
commands. All drives will be stopped, all brakes will engage.



2.5 Control from Local Control Unit (LCU) and Operation Control Unit (OCU)


2.5.1 Activation


There are different ways to activate control from LCU or OCU:

- Standard mode after power-up of the system is OCU control.

- Setting the "All/Local" switch at the drive cabinet to Local will
immediately switch over to LCU control.

- The operator at the OCU can get control from MCS at any time.

- The operator at the LCU can get control at any time from any
control location.

Exception: If an axis is being operated from the PCU, the control will
remain with the PCU.

The procedure for activation of LCU or OCU control is described below.

Note:

Every change of control location will stop the related axis.



2.5.2 Main Menu


The main menu displays all important information such as

- position
- operating mode
- control location
- status

for all three axes.

The main menu offers access to

- axis selection
- status menu
- failure menu
- parameter menu.

The main menu is shown on the next page.



Main Menu

[pic]

Main Menu

2.5.3 Selection of a Control Location


The control location can be selected separately for each axis. Thus, the
procedures below refer to one or more axes as requested by the operator.

The procedure is always as follows:

1. Select axis or axes in the main menu of OCU / LCU by one of the
softkeys:


all axes

Azimuth

Gregorian Dome

Carriage House

Azimuth and Gregorian Dome

2. Press Control

3. Select the desired control location by pressing one of the
softkeys:


PCU

if PCU not connected: Low Level Control, see page 34.

LCU

OCU

MCS.

The new control location for the selected axes will be displayed in the
"Control" line of the main menu.

An invalid entry (e.g. request for OCU operation in Local Only mode) will
not be accepted.

Note:

Every change of control location will stop the related axis.



2.5.4 Activation of an Operating Mode


The control modes can be selected separately for each axis. Thus, the
procedures below refer to one or more axes as requested by the operator.

The procedure always is as follows:

1. Select axis or axes in the main menu of OCU / LCU by one of the
softkeys:


all axes

Azimuth

Gregorian Dome

Carriage House

Azimuth and Gregorian Dome

2. Select the desired operating mode:


Stop

Preset

Stow

Rate


(For description of the individual modes see page 20.)

3. Follow the instructions on the screen to enter desired positions,
velocities etc.

Each entry has to be terminated by .

4. Press the softkey offered for "Execute".

The new control mode for the selected axes will be displayed in the "Mode"
line of the main menu. The respective mode will be activated.

An invalid entry (e.g. positions out of range) will not be accepted. If
actual failures inhibit activation of a particular mode, the command will
not be accepted. The system will remain in Stop mode.

AUX mode requires the "Brake Interlock Override" switch to be activated.



2.5.5 Auxiliary Mode


For a description of AUX mode see page 22.

The AUX mode can be activated for each axis separately. The procedure is as
follows:

1. Select one axis in the main menu of OCU / LCU by one of the
softkeys:


Azimuth

Gregorian Dome

Carriage House

2. Press AUX.

3. Select the drives or drive groups to be disabled by moving the
cursor to the desired motor or group.

4. Press Execute to disable the motor or group selected. Press
Aux Off to remove the auxiliary mode selection. Only one motor or one
group can be set to Aux at a time.

5. Press or to return to main menu.



2.5.6 Status Display


The present status of the servo drive system can be displayed by pressing
Status in the main menu.

On the first page the actual motor torques etc. are displayed, on the
second page the actual I/O status of the PLC is shown.



2.5.7 Failure Display


If an axis is in a failure conditition this will be indicated in the main
menu. By pressing it is possible to scroll through the failure menus.
The sequence is

general failures --> failures Az --> failures GD --> failures CH.

Any present faults are displayed in these menus. By pressing Reset a
Failure Reset can be performed (see page 42). The failure menus can be left
at any time by pressing .



2.5.8 Parameter Menu


In the parameter menu some system parameters can be modified by the user.

The parameter menu can be reached by pressing in the main menu.

The following parmeters can be set:

encoder correction offset to be added to the encoder readings

(separately for each axis).

Limits will be shifted accordingly,


host timeout timeout in MCS mode for automatic STOP

after last communication to MCS


Program Track time offset offset to be added to the actual time
to adjust

drive system to a commanded Program Track path

The parameters can be changed with all axes in Stop mode only.

Note:

Safety-relevant parameters are fixed in the PLC software and cannot be
modified by the user. They are accessible by maintenance staff only.



2.6 Control from Portable Control Unit


The layout of the Portable Control Unit is shown on page 13.

Attention!


The PCU is designed for outdoor use. However, in order to protect the
PCU from ingress of moisture, some precautions should be taken:


The PCU should not be left in the rain for longer periods. After use
store it in a place protected from rain (i.e. in a room, under a roof
etc.).


If the PCU is left outdoors unprotected, never leave it face up but
with the back side up.


2.6.1 Activation and Preconditions


The operation of the PCU can be activated in two different ways:

- Enable PCU mode at LCU, OCU or MCS and plug in the PCU at any PCU
connection box.

- If the PCU is plugged in at any connection box and an axis is
activated (see below), this axis is forced to PCU mode.

Preconditions (see page 25):

- power on
- no emergency stop condition
- serial interface from PCU to PLC working correctly (checked after
plugging in the PCU only).

After plugging in the PCU at one of the PCU connection boxes the green +24V
light at the PCU must be on.

If the PCU communication does not work,

- the display is switched off after a few seconds

- the operationality of the CPU can be checked by pressing the "mode
select" pushbutton

- no values for position and current are displayed.

Attention!


As soon as the PCU is connected the emergency pushbutton on the PCU is
active. All axes will be stopped when this E-stop is pressed!



2.6.2 Axis Selection


Once the PCU is connected, pressing the "mode select" pushbutton scrolls
through the various axes:

no axis selected Azimuth Gregorian Dome Carriage House #1 no
axis .

The limit and brake status displayed at the PCU always refers to the axis
presently selected. The actual position and the motor current of this axis
are displayed on the LCD display.

Scrolling through the axes does not impact any ongoing operation. It does
not request control to be given to the PCU.

Only single axis control is possible from the PCU. Only RATE mode is
available. Any AUX status - if activated - is maintained during PCU
operation. All limits and interlocks are active.


2.6.3 Axis Activation and Control


To operate an axis, observe the following command sequence:

- select axis

- set "Drive On/Off" switch to "On". If the switch has been in the
"On" position before selecting this axis, it has to be switched back to
"Off" and then to "On" again.

Attention!


As soon as the "Drive On/Off" switch is set to "On" the axis is
activated.

The control is forced to the PCU if it has not yet been given control.

Any ongoing movement will be stopped immediately.

As long as an axis is switched to "on", no other control location
can get control for this axis.

- select desired velocity with the potentiometer (cw = positive)

- set "Move Command Ready/Go" switch to "Go".

The axis will move with the velocity commanded by the potentiometer. If
the switch has been in the "Go" position before, it has to be switched
back to "Ready" and then to "Go" again.

- stop movement by switching to "Ready". Axis still may drift very
slowly!

- apply brakes by switching to "Off".

Note:

The slew velocity in PCU mode is limited to 50% of the maximum slew rate.

2.7 Computer Mode (Control by MCS)


2.7.1 Activation


Control from the host computer (MCS) is established through a fiberoptic
Ethernet link between the PLC (CP581) and the MCS in the main station
building.

The computer mode is activated by the softkey "MCS" in the main menu of OCU
or LCU. For operation from MCS the "Local Only Switch" of the respective
axis has to be in the "All" - position.

MCS can take control from OCU at any time without OCU having to hand it
over, and vice versa. If the MCS link is lost, the control is transferred
back to the OCU.



2.7.2 Commands


For details about the available MCS commands and the PLC monitor messages
see section 2, LAN Interface Description.



2.8 Low Level Control from Drive Cabinet


2.8.1 Function


A low level control for all axes is offered at the Drive Control System
units. It allows jog mode operation with forward/reverse pushbuttons, the
veloctiy being selected by a poitentiometer. Only PLC interlocks are active
in this mode, all analog signals are generated and evaluated in the DCS. No
working interfaces (to PCU, CP581, MCS etc.) are required.

Only Rate mode is available. Limits and interlocks are active without
restrictions. The software velocity and acceleration limiters are not used.
The hardware limiters inside the DCS are active.



2.8.2 Activation


The DCS control can be activated in two ways:

- If the PLC internal interface to the CP581 (and thus to LCU, OCU
and MCS) is not operational and the PCU is not connected, DCS control
will be activated automatically.

- If PCU mode is initiated at LCU, OCU or PCU but no PCU is
connected, DCS control will become active.


2.8.3 Operation


Each axis can be operated in DCS mode independently.

In DCS mode simply press the pushbuttons at the DCS front panel and the
axis will move with the velocity selected by the potentiometer.

2.9 Interlocks And Alarms


2.9.1 Limit Switches


A system of limit-switches protects the trucks and trolleys from travelling
into the hard stops (cf. page 14).

The system of limit switches consists of

- pre-limit switches

- operating limit switches

- emergency limit switches

The limits are arranged as follows:


äääääääääääääääääääääääääääääääääääääääääääääääääääääää

| | | | | | | |

| | | | | | | |

| | | |--- prelimits ----| | | |

| | |------ softlimit -------| | |

| |----------- operating limit ------------| |

|---------------- emergency limit -----------------|

| | | | | |

| | |<------- total operational travel range ------>|
| |

| | | | | |

Function Of The Limit Switches:

Prelimit The prelimits exist as hard and soft limits in both
directions.

When passing a prelimit moving towards the final
limit the velocity will be reduced to 1/10 of the
maximum speed.


In azimuth there is no hardware prelimit.

Soft Limit If the end of the specified travel range - derived from
the encoder position - is reached, the drives will be
stopped and the brakes will engage. Leaving the limit
in the opposite direction is permitted.

This is a mere software function.

Operating Limit A hardware limit switch indicates the end of the
permissible travel range. It is evaluated by the PLC.
The function is the same as for the soft limits.

Emergency Limit An additional mechanical limit switch (also
mechanically independent from the operating limit
switch) which cuts the drive and brake power if
encountered. This limit can only be left be moving
the drive back mechanically.

Collision protection (GD and CH#1 only)


A software function will stop the motion of both GD
and CH#1 if the distance between them is lower than a
predefined value. Operation is permitted in the
opposite direction.

An additional mechanical limit switch will switch off
the drive power if the distance between Gregorian
Dome becomes too small.

Setting of the Soft Limits

The travel ranges in the PLC are limited as follows:

Azimuth 0 ... +720 deg

Gregorian Dome 1.05.... 19.70 deg

Carriage House #1 -0.24 ... 20.00 deg

For adjustment of the hardware switches see section 4, modifications and
adjustments.

The softlimits can be changed in the PLC, DB50, DW150ff, using a PC with a
Step5 development system. Observe units indicated in the PLC listing or
online when editing DB50. Modifications will remain active until a new
[cold] restart of the PLC has been performed (cf. par. 43). To make the
changes permanent DB151 must be modified offline and a new Eprom has to be
blown.

Warning!


Changing soflimits is dangerous and might elimininate the first safety
level of the drive system.


Any chnages should be done very carefully if the mechanical situation
really requires to do so. The changes should be entered by the systems
engineer only.



2.9.2 Other Limits


The motion of the axis is limited by further restrictions, in addition to
the travel limits:

Azimuth:

Cable Car Interlock The feedarm must not enter a particular area
when the cable car is moving. The Az axis will stop
when reaching this area during cable car movement.
The interlock area is reached when either softlimits
or the CC hardware limits are encountered.


Vice versa, an "Cable Car Inhibit" signal is fed to
the cable car control system in order to inhibit
operation of the cable car when the feedarm is inside
the collision area.

Gregorian Dome / Carriage House:

Collision protection A software function will stop the motion of both
GD and CH#1 if the distance between them is lower
than a predefined value. Operation is permitted in
the opposite direction.

An additional mechanical limit switch will switch off
the drive power if the distance between Gregorian
Dome and Carriage House becomes too small.

Counterweight Interlock

The actual travel limits of Gregorian Dome and
Carriage House vary depending on each other's
position (see diagram below).


Prelimits and operating limits for GD and CH are
calculated inside the PLC considering the actual
positions of both GD and CH.

Counterweight Interlocks between Gregorian Dome and Carriage House

[pic]
Setting of the Soft Limits

The axis travel ranges in the PLC are limited as follows:

Cable Car Interlock areas (Az) < 5.0 deg

134.0 ... 185.0 deg

314.0 ... 365.0 deg

494.0 ... 545.0 deg

674.0 ... 725.0 deg

Collision distance GD - CH 8.27 deg

Counterweight interlocks CHmin at GDmax 0.00 deg

GDmin at CHmax 1.06 deg

GDmax at CH zero 19.69 deg

CHmax at GD zero 20.00 deg

This setting of the conterweight interlocks in practice disables any
restriction between Carriage House and Dome.

The softlimits can be changed in the PLC, DB50, DW160ff, using a PC with a
Step5 development system. Observe units indicated in the PLC listing or
online when editing DB50. Modifications will remain active until a new
[cold] restart of the PLC has been performed (cf. par. 43). To make the
changes permanent DB151 must be modified offline and a new Eprom has to be
blown.

Warning!


Changing soflimits is dangerous and might elimininate the first safety
level of the drive system.


Any chnages should be done very carefully if the mechanical situation
really requires to do so. The changes should be entered by the systems
engineer only.

2.9.3 Limit Override


The Limit Override function allows movement of Gregorian Dome or Carriage
House out of the emergency limits by electrical means without jumpering any
limit switch signals. The hardware collision protection switch also is not
active with Limit Override. Only movement out of the limit is allowed by
the PLC. A hardware failure might, however, cause the system to move in the
wrong direction in spite of the commmand; see warning below.

The override function is active in PCU mode only.

For enabling the Limit Override function, the key switch at any of the PCU
connection boxes has to be activated. The key can only be removed in the
normal position, not in the override position.

Warning!


If the Limit Override function is required an emergency limit has been
hit. This means that some other interlocks did not work for whatever
reason. Make sure that any failures and malfunctions have been
discovered and resolved before operating the respective axis again!


With Limit Override active some very important safety features are
disabled.

Any axis movement should be initiated with ultimate caution. Watch the
drives closely during movement!


Please observe that the same failure that has caused the system to move
into the emergency limit could also cause the system to move further
into the limit disregarding the commanded signal!



2.9.4 Failures


Servo Failure

If one of the servo amplifiers reports an error, the stop sequence for the
respective axis is activated. It is possible to drive the axis in AUX mode
with reduced performance (cf. page 22).

Brake failure

Faulty operation of one brake immediately activates the stop sequence for
the respective axis. Failure of any brake will require Stop mode since the
axis is mechanically blocked. Function of the brakes is supervised by
measuring the sum brake current.

No Motion

If a drive does not start to move although it has been enabled and a
velocity setpoint has been sent, the stop sequence for the respective axis
will be activated.

Runaway

If the position transducers report a d/dt which is greater than the maximum
theoretical value, a "runaway" situation will be assumed and the stop
sequence for the respective axis will be activated.

Emergency Stop (cf. page 44)

Emergency stop is used to prevent danger for persons or damage to the
positioner. By pressing the respective switch drive power supply is cut
off. All drives and the brakes will be switched off.

Overtemperature

In case of motor or amplifier overtemperature the respective axis will be
locked. Aux mode for a group of amplifiers and motors without fault is
allowed.

PLC Watchdog

The PLC CPU has an internal watchdog. If the software crashes or gets stuck
e.g. in an endless loop, the CPU will automatically go to STOP mode. All
outputs will be set to zero.

CP581 Watchdog

The PLC CPU checks the faultless operation of the CP581. If there is no
more communication, OCU, LCU or remote control will be disabled.

Host Watchdog

If there is neither command nor status request from the host computer
within a user selectable timeout period, the remote control will be
disabled. Any axis that has been in Remote will be switched to OCU control.

2.10 Reset


2.10.1 Failure Reset


A failure always indicates malfunction of one part of the subreflector
positioning system. The system has to be carefully checked to find out the
reason for this failure.

After any important failure a failure reset is necessary. This is to ensure
that the failure has been acknowledged and/or eliminated.

If the failure is still present when pressing "Reset", the failure status
cannot be cancelled. Otherwise the failure indication will be switched off.

A Failure Reset is possible

- via keyboard from OCU, LCU and MCS ( in failure menus).

- with the Reset pushbutton at the drive cabinet

- in PCU mode with the Reset pushbutton at the PCU.

Reset functions:

- Reset with pushbutton at drive cabinet:


All present failures will be cancelled.

- Reset from PCU:


General failures and those of the active axis will be reset.

- Reset from LCU, OCU and MCS:


. A General Reset command will reset general failures only (e.g.
cabinet overtemp.)

. Axis related failures (e.g. amplifier not ready) have to be reset per
axis

using the Axis Failure Reset command (in the axis failure menus).



2.10.2 PLC Reset


The PLC can be reset in four different ways (cf. PLC manual):

- restart after power down of CPU928
- manual warm restart of CPU928
- manual cold restart of CPU928
- restart of CP581

The correct way of resetting the PLC is as follows:

LCU crashed, "hanging" or not reacting reset CP581

red light at CP581 reset CP581

steady red light at CPU928 manual warm restart of CPU928

blinking red light at CPU928 manual cold restart of CPU928

LCU position displays shows zeros only manual warm restart of CPU928

The procedures how to perform the different restarts is described
hereafter.

After a power failure of the UPS system the individual processors of the
PLC will synchronize automatically as soon as the power has returned.



2.10.2.1 Restart After Power Down of CPU928


This restart is automatically performed when powering up the PLC. It
includes

- resynchronization of CPU with plug-in PC (CP581)

- reset of all motion commands

- limits, timers and loop parameters as before power down.



2.10.2.2 Manual Warm Restart of CPU928


A manual warm restart is performed by switching the Run/Stop switch at the
PLC CPU (cf. section 4 - adjustments, par. 1.1) from Run to Stop and back
to Run.

The functions performed after a manual warm restart are the same as after
power up (see above).



2.10.2.3 Manual Cold Restart of CPU928


A manual cold restart is performed by switching the Run/Stop switch at the
PLC CPU from Run to Stop and back to Run. When switching back to Run the
reset switch at the CPU (just below the Run/Stop switch) must be held in
the Reset position (cf. section 4 - adjustments, par. 1.1).

The functions performed after a cold restart are

- resynchronization of CPU with plug-in PC (CP581)

- reset of all motion commands

- reset limits, timers and loop parameters to the default values.

A cold restart is necessary when the software in the PLC RAM has been lost
after

- unplugging the CPU

- removing the batteries during power down

- unintentional overall reset of the CPU.



2.10.2.4 Restart of CP581


Being very similar to a standard PC, the CP581 can be reset in two ways:

- by pressing + + on the keyboard

(which after serious software crashes sometimes does not work)

- by pressing the "Reset" pushbutton at the CP581 front panel with a
pencil.



2.11 Emergency Stop


Emergency stop pushbuttons are located at

- various locations on the feedarm (six plcs.)

- the Portable Control Unit

- the drive cabinet.

Pressing any of these E-stops immediately switches off the drive power All
drives are stopped, the brakes engage. The E-stop at the PCU, however, is
active only if the PCU is plugged in at any of the PCU connection boxes.

The E-stop condition is signalled at PCU, LCU, OCU and via remote interface
to MCS.

To release the E-stop situation

1. Unlock emergency stop pushbutton(s)

2. Press "Power On" Pushbutton at drive cabinet

3. Re-activate the desired operating mode.



2.12 Special Features


2.12.1 Unbending of Feedarm


Should for whatever reason the azimuth axis run into a real bending limit,
the brakes on the Carriage House side can be opened separately using the
following procedure:

1. Switch Azimuth to "Local Only" at the drive cabinet door.

2. Press pushbuttons "Power On", Failure Reset" and "Lamp Test"
simultaneously.

This procedure will allow the feedarm to unbend. It will, however, not help
in any "fake" case of a beding limit, e.g. after one of the Az encoder
pinions has went off the encoder rack gear.



2.12.2 Brake Interlock Detector


A feature has been implemented at special request to detect if ever a brake
is released without the related servo amplifier being enabled. In normal
operation this should never be the case. If so, the brake interlock relays
would become active and switch off the brakes. In case such a condition
should ever be detected, the following PLC outputs will be set:

- Q 0.5 for Az
- Q 0.6 for GD
- Q 0.7 for CH.

Disabled amplifiers because of an active Aux mode will be considered; the
failure bits will not be set.

The failure bits can only be reset by pressing the pushbuttons
and at the drive cabinet door simultaneously.

Note:

Some failures that cause a sudden stop (e.g. emergency off) could also trip
this failure indicator, because the power is removed from both amplifiers
and brakes.

3 Test And Troubleshooting


3.1 TEST OUTPUTS


Four analog test outputs are available at terminals in the drive cabinet.

They are assigned as follows:

Test Output 1 Azimuth position

Test Output 2 Gregorian Dome position

Test Output 3 Carriage House #1position

Test Output 4 position deviation between Az1 and Az2 encoders

The test outputs provide a voltage of 0...±10V, which is proportional to
the actual position. Center and scale can be adjusted inside the PLC by
means of a Siemens Programming Device (e.g. PG710, PG 770, PC loaded with
Step 5 Software etc.).

Warning!


Modifying the test output parameters is a modification of the software
in the RAM area of the PLC CPU.


This requires basic knowledge about Simatic PLCs, their related
programming language Step 5 and how to use the programming software.

The following parameters can be set:

- center of range (i.e. position at output 0V)

- 10 V range.

All parameters have to be entered in Siemens floating point format (KG)
as multiples of 0.0001 degr.

The parameters have to be adjusted in DB250 as follows:

(cf. PLC software documentation)

| |center |10 V range |
| | | |
|test output 1 |DD 2 |DD 4 |
|test output 2 |DD 8 |DD 10 |
|test output 3 |DD 14 |DD 16 |
|test output 4 |DD 20 |DD 22 |


The values have to be entered in KG format, which is entered as

[sign]AAAAAAAA [sign_exp]EE.

AAAAAAAA mantissa (max. 8 digits)

EE exponent (max. 2 digits)

This value represents [sign].AAAAAAAA [sign_exp]EE.

Example: 50 == KG = +5+02.

Example:

The position range from +25.000 ... +35.000 degr shall be represented by
the range

-10...+10V.

Settings:

center: 30.0000 KG = 3+02

10V range 5.0000 KG = 5+01

Note:

If during modification of the test output parameters in the PLC some other
data should unintentionally be destroyed, it is possible to restore the
data again to the default values if the PLC software is stored in an Eprom
module (which normally is the case). To do so, a "CPU overall reset" and a
subsequent cold restart must be performed (cf page 49).

If the software is presently stored in a RAM module, try a PLC cold
restart. If this does not help, an "CPU overall reset" must be performed.
After that the software has to be reloaded from a floppy.



3.2 Troubleshooting


3.2.1 General Remarks


If a fault in the Servo Drive System is detected, it will be signalled on
LCU and OCU Panel and reported to the MCS.

If many failures are indicated simultaneously without obvious reason (e.g.
all axes in emergency limit position though no movement has taken place),
this always indicates some kind of "general" fault, e.g.

- cable disconnected at local j-box etc.

- control voltage(s) missing.

In such a case check control voltages, connectors etc. before starting to
hunt non-existing individual faults.

Also be always aware of the fact that any indicated fault may have several
reasons:

- The "real" reason (e.g. emergency limit indicated because the
drive has really reached the emergency limit switch)


This is by far the most frequent situation!

- Broken, loose or disconnected wires anywhere on the way from the
"source" (e.g. limit switch, amplifier etc.) to the PLC, signalling an
alarm though the "source" is ok

- Defective switchgear (e.g. relays) in the switch cabinet

- Faulty PLC I/O modules

(e.g. though the LED at the input module indicates that a particular
signal is present [LED lit], the software status may be different if
the module is faulty.)

Anyway every fault must be acknowledged and/or reset by the reset
pushbuttons or functions (cf. page 42).



3.2.2 PLC


3.2.2.1 CPU 928B


If the red LED "STOP" on the CPU is lit, follow the steps below:

1. First try a warm restart (see page 43).

2. If the CPU remains in STOP mode, try a cold restart (see page 43).

All parameters will be set to the default values.

3. If the CPU remains in STOP mode, perform an "Overall Reset".


An overall reset is performed by switching the Run/Stop switch at the
PLC CPU from Run to Stop and back to Run. When switching back to Run
the reset switch at the CPU (just below the Run/Stop switch) must be
held down in the Overall Reset position (cf. section 4 - adjustments,
par. 1.1).

4. Remove Eprom module from CPU (switch off power first!).

5. Set Run/Stop switch on CPU to Run. The Run LED must light now. If
not, change CPU and start with step 4 again.

6. If step 5 has been completed successfully completed, insert Eprom
into CPU again.

7. Perform a cold restart (step 2).

8. If the Stop LED comes on again, there is a communication fault
inside the PLC (e.g. I/O module faulty or not plugged in correctly,
extension unit not connected etc.

Check thoroughly and try step 7 again.

9. More detailed information about the error reason after a CPU Stop
is available from the Istack function of the Step5 programming software
(cf. CPU928 manual).


Note:

Programming device and detailed Step5 knowledge are required to perform
these tests.



3.2.2.2 CP 581


If the red LED "Stop" on the CP581 is lit, follow the steps below:

1. First try a warm restart of the CPU928. It synchronizes the
internal interfaces again (see page 43).

2. If the CP581 remains in Stop mode, reboot the CP581 by pressing
the "Res" pushbutton on its front panel with a pencil etc. Allow
approx. 45s for re-booting.

3. If the CP581 remains in Stop mode, check the CP581 setup.


For this purpose enter + at the LCU keyboard
immediately after rebooting the CP581.


If the setup is incorrect, a related information will be displayed on
the monitor.

Follow the instructions on the screen and modify the setup according to
the information in "Modifications And Adjustments", section 1.3.2.1.

4. After checking the setup reboot CP581 again (cf. step 2).

5. If the CP581 still remains in STOP mode, check whether the files
on the silicon disk are identical to those on the original CP581
floppy. Check proper operation of the DOS operating system.

6. If all this does not help, replace the CP581.



3.2.2.3 CP 524


If the red LED on the CP524 is lit, follow the steps below:

1. Check whether Run/Stop switch on CP524 is in Run position.

2. Perform a warm restart of the CPU928. It synchronizes the internal
interfaces again (see page 43).

3. If the red LED on the CP524 is still lit and the CPU928 is running
(green LED lit), replace the CP524.



3.2.2.4 Digital Output Modules


A red LED on a digital output module indicates a short circuit in at least
one of the eight outputs of that particular byte. The corresponding fault
LED of each output byte is located above the eight green output LEDs.

Disconnect the load of these outputs one by one to find out in which path
the short circuit might be and eliminate its reason.


Any fault must be reset before operation can be resumed.



3.2.2.5 Software


If the CPU stops by itself (red Stop LED lit), this may have hardware
and/or software reasons. If all steps mentioned in the CPU section (cf.
page 49) have been performed without success, it is necessary to evaluate
the reason of the Stop situation using the Istack function of the Step5
programming software (cf. CPU928 manual). Programming device (Siemens PG or
standard PC loaded with Step5 version S5 V3.2 or higher) and detailed Step5
knowledge are required to perform these tests.

3.2.3 Faults Indicated on LCU or OCU


3.2.3.1 General faults


|fault |possible |measures |
| |reason | |
|Emergency Off |E-Stop |Reset E-Stop condition |
| |condition |(cf page 44) |
|Drive power off |Power has not|Press Power On Pushbutton at drive |
| |yet been |cabinet or send Power On command from |
| |switched on |MCS |
| |after system | |
| |power-up or | |
| |E-stop | |
| |Main |Press Reset pushbutton. Try to switch |
| |contactor |on main power again. Main contactor |
| |fault |should react. |
| |E-Stop |Reset E-Stop condition (cf page 44) |
| |condition | |
|Cabinet doors |doors of |close doors |
|open |drive cabinet| |
| |open | |
|24V power supply |main 24V |Check circuit breaker +PD - 21 OL 02 |
|fault |supply |(drive cabinet 1) |
| |switched off | |
|Brake power |power supply |Check circuit breaker +PD - 21 OL 01 |
|supply fault |switched off |(drive cabinet 1) |
|PLC power supply |circuit |Check circuit breaker +PD - 26 FU 02 |
|fault |breaker for |(drive cabinet 3) |
| |PLC outputs | |
| |tripped | |
|Mains |mains voltage|Check mains voltage. |
|over-/undervoltag|outside ±10% |WARNING! |
|e |range |Overvoltage is dangerous and may cause |
| | |damage to the equipment. Only some |
| | |components can (and will) be switched |
| | |off automatically in case of |
| | |overvoltage. |
| | |In case of mains overvoltage switch off|
| | |power to the cabinet immediately by |
| | |using the main breaker +PD-20CI01 in |
| | |the leftmost cabinet! |
|Drive cabinet |cabinet fan |Check adjustment of the thermostats. |
|overtemp. |not working |Fan should be switched on at 25œC, |
| | |overtemperature condition is at 35œC. |
| |ambient temp.|Check ambient temperature in |
| |too high |electronics shelter (+5...+30œC). |
| |heat source |Check for any extraordinary heat |
| |inside drive |sources |
| |cabinet | |
|PCU communication|CP 524 |Perform warm PLC restart (see page 43) |
|fault |initializatio| |
| |n fault | |
| |communication|Press Reset pushbutton at drive |
| |error CP524 -|cabinet. If failure is gone, the reason|
| |PCU |most probably was a data transfer error|
| | |between PCU and CP524. Should this |
| | |happen more frequently, check shielding|
| | |of cable from CP524 to PCU. If failure |
| | |continues after Reset, the |
| | |communication is completely down. |
| | |Continue on page 56. |

|fault |possible |measures |
| |reason | |
|CP581 |CP 581 |Perform warm PLC restart (see page 43) |
|communication |initializatio|and reset CP581 (see page 50) |
|fault |n fault | |
| |CP581 |Reset CP581 (see page 50) |
| |watchdog | |
| |failed | |
|Network error |LAN interface|Check LAN connection to MCS. MCS must |
| |does not work|be operational. To resume communication|
| | |a reset may be required on one or both |
| | |sides. For CP581 reset see page 50. |
|Host timeout |MCS is not |same as network error (see above) |
| |communicating| |
|Collision switch |Collision |Check reason why the softlimit has been|
|encountered |protection |passed and the hard limit hit. Move GD |
| |switch GD-CH |or CH out of the limit using the limit |
| |hit |override function (see page 40) |
|Bending Limit |encoder rack |Increase bending limit value inside PLC|
|(allowable |gear not |(DB50, DW103). Measure bending as a |
|difference in Az |circular |function of az angle over 360 degrees. |
|encoder readings | |Correct rack gear and/or bending limit |
|exceeded) | |value if necessary. |
| |real bending |"Unbend" feedarm: press "Power On", |
| | |"Lamp Test" and "Failure Reset" |
| | |pushbuttons at drive cabinet |
| | |simultaneously. Az axis must be in Stop|
| | |and "Local Only" switch must be in |
| | |"Local". (Cf. par. 2.12.1). |
| |one of the Az|Check rack gear for irregularities. |
| |encoders has |Check encoder spring; encoders must be |
| |"jumped" |pressed tightly to the rack gear over |
| | |the full Az range. Move to the encoder |
| | |reset position and reset encoders. |
| |encoder |Disconnect the faulty encoder. Replace |
| |failure |as soon as possible. |
|Limit override |Limit |Do not leave system in this condition |
|active |override |unless required for maintenance or |
|(status, no |function |repair purposes! |
|fault!) |active | |
| |(see page 40)| |


3.2.3.2 Axis Related Failures


The failures listed below are indicated for each axis separately. They have
to be reset by the related "Axis Reset" command (by MCS, LCU or OCU) or by
pushbutton "Reset" at the drive cabinet.

The label in the table below has to be replaced by either Az, GD or CH. It
refers to the equipment labels used in the circuit diagrams in Vol. III,
Installation Manual.


|fault |possible |measures |
| |reason | |
|Amplifier |Servo |see page 59 |
|fault/overtemp. |amplifier | |
| |failure | |
|Amplifier not |conditions |see page 59 |
|ready |for amplifier| |
| |operation not|Note: A brake failure frequently comes |
| |fulfilled |along withan "amplifier not ready" |
| | |failure, because the brakes will engage|
| | |immediately by hardware and software |
| | |interlocks, if an amplifier is not |
| | |ready. |
|Motor |motor |Check motor temperature. If hot, check |
|overtemperature |overtemp. |reason for overload (mechanical |
| | |blocking, torque setpoint etc.). |
| | |Otherwise check wiring. |
|Power supply |circuit |Check circuit breakers + - 1 OL 01 and |
|fault |breaker |- 1 OL 02 |
| |tripped |(Az, CH: drive cabinets 1; GD: drive |
| | |cabinet 2) |
|DC bus fault |DC bus relay |Readjust relay (see section 4, |
|(Bus voltage too |misadjusted |"Modifications and Adjustments", par. |
|high) | |8.1. |
| |Regeneration |Check regeneration unit(s) of that |
| |not working |particular axis |
|Brake group # |circuit |Check circuit breakers +PD - 27 FU 01 |
|fault |breaker for |thru 05 |
| |brake tripped|(in drive cabinet 3) |
|Brake failure |Brake not |Check brake function by watching the |
| |released |brake making "click" when being |
| | |released. If no sound,.check outgoing |
| | |voltage from the brake relay in the |
| | |drive cabinet to the brake itself |
| | |according to circuit diagram. |
| |Brakes not |False feedback from brake current |
| |closed though|relay. Check wiring and potential |
| |supposed to |outside influences that could trip the |
| | |brake currrent relays, e.g. radios used|
| | |inside the electronics shelter with |
| | |cabinet doors open. |
| |Brake current|Readjust relay (see section 4, |
| |relay |"Modifications and Adjustments", par. |
| |misadjusted |8.2. |

|fault |possible |measures |
| |reason | |
|Motion failure |No motion |No position change has been registered |
| |after enable |after drive enable. Make sure that: |
| | |- drive is not blocked mechanically |
| | |(try opposite |
| | |direction!) |
| | |- amplifier is enabled (ENABLE LED on) |
| | |- rate setpoint arrives at servo |
| | |amplifier |
| | |- motor cables are connected and not |
| | |interrupted |
| | |- encoder is connected and operational.|
| |moving in |Movement in wrong direction has been |
| |wrong |detected. Check wiring of velocity |
| |direction |setpoints and feedbacks. Try operation |
| | |from DCS (cf. par. 2.8); if this |
| | |works, the problem is neither between |
| | |DCS and motors nor between motors and |
| | |amplifiers. |
| |Runaway |Motor movement was too fast. Make sure |
| | |that: |
| | |- motor resolver is connected correctly|
| | | |
| | |- encoder is connected and operational |
| | |- rate setpoint is transferred |
| | |correctly. |
|Servo failure |various |The "servo failure" is a summary |
| | |signal. Observe individual failure |
| | |messages for more details. |
|Encoder failure |encoder |Check +24V power supply to WF705. |
| |evaluation |Perform a warm PLC restart (see page |
| |module WF705 |43). |
| |(in PLC) not | |
| |operational | |
| |encoder fault|Encoder faulty; cf. page 58. |
|Pendulum alarm |wiring |check wiring |
|(Az only) | | |
| |velocity loop|Check velocity feedback from amplifiers|
| |interrupted |and torque command to the motors at |
| | |DCS. |
|Reset is possible|real alarm |Check for any obvious reason. Try Az |
|after 60s only to| |movement at a different location. |
|allow | | |
|oscillations to | | |
|calm down. | | |


3.2.4 Unit Failures


3.2.4.1 OCU


|fault |possible |measures |
| |reason | |
|OCU not |PC hardware |Check hardware and software setups as |
|operational |or software |for a standard PC |
| |fault | |
|Communication |wiring |Check wiring from OCU port COM1 to |
|fault |interrupted |CP581 / COM2 |
| |power supply |Check power supply for fiber optic |
| |for fiber |converters at both OCU port COM 1 and |
| |optic |CP581 port COM2. |
| |converters | |
| |missing | |


3.2.4.2 PCU


For servo failures refer to the previous paragraph (axis failures).

A "PCU communication error" reported by the PLC always indicates a general
failure somewhere between PCU CPU and PLC. Follow procedure below.

For all tests decribed below the PCU must be connected to one of the PCU
connection boxes.


|fault |possible |measures |
| |reason | |
|24V LED off |PCU power |Check wiring according to circuit |
| |supply |diagram +PLC page 1 thru 5. |
| |missing | |
|no display |no axis |Press Mode Select pushbutton. If |
| |selected |display comes up shortly but does not |
| | |remain after releasing the pushbutton, |
| | |continue with #3. If display does not |
| | |come up at all, continue with #4. |
|no permanent |PLC in Stop |Restart PLC (see page 49). |
|display after mode |mode | |
|select | | |
| |Current Loop |Check TxD and RxD lines. 20mA must be |
| |Interrupted |measured on both lines according to |
| | |circuit diagram +PLC page 1. |
| |Communication|Perform warm PLC restart (see page 43).|
| |error PLC - |Red LED at CP524 must be off. Check |
| |PCU |wiring between PLC and PCU according to|
| | |circuit diagram +PLC page 1 thru 5. |
|no display at PCU |PCU internal |Check PCU wiring according to |
|even when pressing |wiring |manufacturers documentation |
|Mode Select |damaged | |
| |CPU faulty |Replace CPU of PCU |


3.2.4.3 Optical Encoders


In case of an encoder fault proceed as described hereafter.

First verify that the encoder evaluation module WF705 inside the PLC is
operational. The WF705 can assumed to be not operational if all encoders
report a failure.

1. Check 24V power supply to WF705 (circuit diagram +Az page 22)

2. Perform a PLC warm restart in order to re-initialize the WF705
module

(see page 43).

After the proper function of the WF705 module has been verified, proceed
with checking the encoder itself.

1. Verify that encoder connectors at WF705 module are plugged in.

2. Verify that the connector at encoder interface module PT15/2
(circuit diagram labels +Az/GD/CH - 22D02, 23D02; mounted in drive
cabinet 3) is correctly plugged in.

3. Verify that the connector at the encoder itself is plugged in.

4. Connect spare encoder and reset failure condition. If failure
persists, go on with step 5.

5. Measure power supply at encoder connector:

+24V must be measured between pins 11 and 12.

6. Check wiring between WF705 (in PLC) and encoder interface module
PT15/2

as shown on circuit diagrams +Az/GD/CH pages 22 and 23.

7. Check wiring between encoder interface module PT15/2 and encoder

as shown on circuit diagrams +Az/GD/CH pages 22 and 23.

Note:

After replacing an encoder the related axis must be calibrated again. See
section 4, "Modifications and Adjustments", par. 3.2.



3.2.5 Servo Amplifiers


Status during operation:

- green LED "Control Volts" on
- green LED "Enable" on or off depending on the drive status
- green LED "Drive Ready" on
- all red LEDs off.

If the main power is not switched on, the "Undervolts" LED will be lit and
the green "Drive Ready" LED will be off.

The "Overspeed" LED may indicate either a missing or wrong connection of
the motor resolver (cf. amplifier manual) or a real overspeed situation
(runaway, cf. page 55).

For further troubleshooting measures in case of amplifier failures refer to
the manufacturer's manual, chapter 5.



3.3 Exchange Of Components


If any components of the Servo Drive Control System have to be replaced
(either because they are faulty or to find out whether they are faulty),
please observe the section 4 of this manual, "Modifications and
Adjustments".

Make sure that the spare component is set up as indicated in that manual.

For some components additional adjustments may be necessary. Follow the
instructions in "Modifications and Adjustments".

Other components (e.g. PLC I/O modules) may require a setting depending on
its application, e.g. a PLC address. If so, this is also indicated in
"Modifications and Adjustments".





4 Maintenance


4.1 REGULAR MAINTENANCE


4.1.1 Portable Control Unit


In order to protect the electronic components of the Portable Control Unit
(PCU) from moisture that possibly could make its way into the housing, some
drying powder has been placed inside the PCU. Vertex recommends to replace
the drying material every six months. If the PCU has been left face up in
the rain (see precautions given on page 32), the drying powder should be
replaced as soon as possible.



4.1.2 PLC RAM Buffer Battery


The buffer battery inside the PLC power supply chassis has a life time of
approx. 3...5 years. Low battery voltage will be indicated by a yellow LED
at the front of the power supply chassis.

Even if the buffer battery is low the PLC RAM is buffered in case of a
power failure by an additional internal NiCd accumulator. Buffer time is
approx. 2 weeks.

The buffer battery should be replaced after the "Battery Low" condition has
been indicated. Replace battery as described in the Siemens Manual S5-135U,
Vol. 1, Section 4.3.4. Leave PLC power switched on in order to avoid any
loss of PLC RAM information.

The accumulator should be replaced every six years as a preventive measure.
Follow procedure as described in Siemens Manual S5-135U, Vol. 1, Section
4.3.4.



4.1.3 Brakes


The brakes inside the drive motors should be inspected regularly at least
every six months. It should be checked whether there is any moisture inside
the motors and whether the thickness of the brake friction disc is above
the minimum thickness of 0.230 in (5.84 mm). If the thickness happens to be
below this value, replace disc or send motors back to the manufacturer for
brake disc replacement.

For measuring the thickness of the brake disc follow the instructions given
in Vol. IV, Vendor Publications, section 2.1.



4.2 Safety during maintenance


If motion of the axis under maintenance could cause danger for people, the
maintenance personnel has to ensure that no other person can operate this
axis. The safest way is to switch off the entire axis.

This can be done by using the key operated "Local Axis Disable" switch at
the drive cabinet. During work the key should be kept by the maintenance
crew.



4.3 Various Maintenance Instructions


Some instructions for several frequently occurring maintenance and repair
works are listed below. Most of the are also included in Vol. IV, Vendor
Publications.



4.3.1 Precautions During Motor Replacement


Before removing of a motor the two connectors at the motor have to be
loosened. If a spare motor is not installed immediately afterwards, the
following instructions have to be observed:

- Unplug resolver connector (C2) at the related amplifier in the
drive cabinet.

Otherwise the resolver supply voltage might be shorted at the pins of
the motor connector. This in return could destroy the amplifier itself.

- Protect motor connectors against ingress of water (by cover,
hanging upside down etc.).



4.3.2 AUX Mode


As mentioned in paragraph 2.3.6, one or several motors per axis can be
disabled if there is a problem woth one of the power supplies, motors,
amplifiers or cables etc.

Since the control system cannot tell the reason why the AUX mode has been
enabled, the entire drive group will be left diabled. This includes

- 1 motor (GD, CH) / 4 motors (Az)
- 1 amplifier (GD, CH) / 4 amplifiers (Az)
- 1 power supply with its DC bus (Az).

Therefore in AUX mode the motor heating during standstill not be active for
the disabled motor(s).

Attention!


The motor heating should not be left disabled for a longer time period
in order to avoid any condensation inside the motors.


Therefore use AUX mode only when this is really necessary!






-----------------------
[1]) identical for GD and CH