Chapter 4 - Building Rotation Control


The building for NTT was delivered by the contractors, complete with all necessary electrical equipment. In order to perform computer control from the VME side, the building control panel has "automatic control" selection switches for the various functions. Note that this "automatic control" means controlled with the VME computer as opposed to push-button control.

This section describes the control interface and an operating procedure. Each building subsystem is described in a separate section.


The following sections give specific information:


The building automatic control is built around a VME system containing an Ethernet interface to communicate with the main computer. The VME system controls the following subsystems:

These subsystems are described separately in the following sections.

Note: The Air condioner is a self supporting unit, provided by the building subcontractor. In case of a malfunction, a checkout at the Air condioner Local Control Unit must be carried out.


The signals in Subsection 4.12.1 explain themselves; two output signals are provided: to inflate or deflate. In addition, two corresponding input signals which sense the status of the bottom seal. The last signal informs the VME computer if the bottom seal function is in automatic selection mode, i.e. can be commanded via the VME computer.

A hardware interlock is provided so that no building rotation is possible when the bottom seal is inflated.

The sequence to inflate is:

After 50 seconds :

For deflating, the sequence is the same, but use the signals BSDEFLO* and BSLSDEFI*.


A similar I/O structure as for the bottom seal applies to the flaps.

Maintenance Information

The Trivolt power supply has to be adjusted according to the cable length:


The building rotation (called rotation in the following section), is controlled via position sensors between building and azimuth box.

The Control System is in principle a self supporting system, i.e. it does not need any servo loop software. It will be explained in detail in Subsection 4.6.1.

4.6.1 Rotation Position PI Controller

This PI controller is especially designed for the building rotation, and has the following features:

Sensor Inputs

The sensors are Hottinger Baldwin type W50TS combined with an amplifier type MGT 233.0. The two position outputs have a sensitivity of 0.2 V/mm. The PI card inputs have a differential receiver with selectable grounding.

As the measuring amplifier has ground referenced outputs, the ground connection can be left open in the actual system. But during test and integration the jumper must be in one or the other position and a grounding system checkout must be done before the jumper is removed. The sensor tip is replaced with a type that has a rolling ball.

Position Offset

This is an analog computer output to the PI controller: ROPOSOFF????. The scaling is 1 degree/Volt. If the digital signal Apply Position Offset (ROPIAPOO*) is active, ROPOSOFF???? makes it possible to offset the building with respect to the azimuth. This can be necessary in the following cases:


Before the actual PI controller amplifier, a breakout point is provided to implement a filter if necessary. This can be used in order to optimize the open loop performance of the position loop. In the actual system, this possibility is not used.


The PI controller generates an interlock in each of the following cases:

In order to move out of a 3 degree interlock, the following procedure is foreseen:

Building Rotation Drive Enable

The building drive system can be enabled and disabled without switching power. This feature makes enabling possible only when it is required. This enable can be done in two ways:

Both possibilities are "wire OR-ed" in the hardware. This means that one of the two is sufficient to assert RODRENABO.

Building Rotation Drive Enable By Hardware

The PI card generates the building drive enable in each of the following cases (OR function):

In practice, these two settings are not independent because of the fact that only a relatively low integral gain can be allowed. A higher integral gain will cause limit cycles. The switching level is therefore determined by the speed command.

When the drive system is enabled, the rotation system tries to decrease the position error to 0 and the system is kept enabled as long as there is a certain minimum speed.

If both position error and speed are within the limit, then the system is kept enabled during an adjustable time, which prevents too fast enable/disable switching. This delay is set to 7 seconds.

During test and integration, jumper J5 can be inserted on the PI card to enable the building continuously, i.e. independent of position error or speed.

Building Rotation Drive Enable By Software

Asserting of RODRENABO also enables the building drive. This is an OR function with the PI controller signal. This signal makes it possible to enable the building drive continuously if this is required for any reason, e.g. fast and stepwise motions.

Note, however, that the position PI controller provides only an output signal to the rotation velocity loop if at least one of the conditions, mentioned in the previous paragraph, is fulfilled. If not, the velocity reference is zero.

Velocity Reference

The velocity reference is fed to the building electronic racks via an isolation amplifier. This is done to have a complete galvanic isolation between building drive systems and VME computer.

Operating Procedure

Most of the important items concerning operating the building system have already been explained in the previous paragraphs. More is described in the next paragraph.

Switching the Rotation System On and Off

A certain sequence of commands and checks has to be done to switch on the building rotation drive system:

To switch the rotation system off:

Maintenance Information

The description above and the electrical drawings and data sheets provide the basic information for maintenance. As a help, a list of scaling values and the adjustment procedure for the position PI controller is described below.

Scaling Values of the PI Controller


Interchanging of the PI controller board for a spare one means also that the position loop has to be adjusted. The procedure is as follows:



The signals in Subsection 4.12.7 explain themselves; two output signals are provided: to open or close. In addition, two corresponding input signals which sense the status of the door. The last signal informs the VME computer if the door function is in automatic selection mode, i.e. can be commanded via the VME computer.


Refer to Subsection 4.12.8. The implementation of the slit shutter signals is done as follows: one bit is provided to switch the 380V power. Two bits are provided which need an impulsive signal in order to start and to stop the motion. The direction is controlled by another bit. The length of the impulsive signals has to be 3 seconds.


Refer to Subsection 4.12.9. The implementation of the windscreen signals is as follows: one bit is provided to switch the 380V power. Two bits are provided which need an impulsive signal in order to start and to stop the motion. The direction is controlled by another bit. The length of the impulsive signal has to be 100 milliseconds. Another signal is provided which senses if the chain of the windscreen is broken: WSLSCHI*. If this signal is asserted, no operation is possible.

4.9.1 Absolute Encoder

The absolute encoder is manufactured by Siemens. A similar type is also used for the windscreen and the rotation. From the control side, two possible different types can be implemented:

Together with a choice of gear reduction, a good scaling value can be chosen. The absolute encoder has BCD outputs. Digit 3 is not used for the 1000 counts type. The encoder type V23463-K0901-D315 (100.000 counts, 100 turn) can be used, but the fifth decade is not connected.

4.9.2 Line Driver/ Receiver

Because of the long distance between encoder and VME rack, a line driver/receiver link is designed. The line driver and the power supply are located close to the encoder. The receiver is mounted in the VME rack.

In order to eliminate electrical interference problems, this link has its own power supply (which also powers the line receiver) and has Opto-couplers between the receiver IC's and the VME inputs.


Refer to Subsection 4.12.2. The emergency stop buttons, installed in the rotating part of the building, are routed to the building VME rack. There is a computer signal generated for each switch, using 1 contact of the button. The other contact of each button is put in series and forms a part of the Emergency Stop push-button chain. For a complete picture of this chain, refer to Subsection 1.5.2.


Refer to Subsection 4.12.11. The signal 380VPFI* indicates a power failure in the building main power distribution. It has been implemented to make it possible for the software to detect power failures. Neither the VME nor the TCS Workstation suffer from a power failure because they are connected to the un-interruptable power supply.

The software action on a power failure has to be: stop driving any building function immediately.


The signals in the building subsystem are divided into the following groups which indicate where the signals originate (inputs to the computer), or where they have to be routed (outputs from the computer).

4.12.1 Bottom Seal Signals

BSINFLO*DO*1Bottom Seal inflate command
BSDEFLO*DO*1Bottom Seal deflate command
BSLSINFI*DI*1Bottom Seal Limit Switch, seal inflated
BSLSDEFI*DI*1Bottom Seal Limit Switch, seal deflated
BSAUTSELI*DI*1Bottom Seal, automatic control selected

4.12.2 Emergency Stop Button Signals

The switches detailed below are mounted in the rotating part of the building and have no direct connection with any other VME computer; the switches are numbered as shown.

ESBUCO05I*DI*1Building Control (tech. service. room) switch
ESCORO06I*DI*1Control Room switch (6)
ESCORO07I*DI*1Control Room switch (7)
ESEMRO08I*DI*1EMMI Room (big inst. room) switch
ESWSRO09I*DI*1Windscreen area (9) switch
ESWSRO10I*DI*1Windscreen area (10) switch
ESIRRO11I*DI*1IRSPEC Room (small. inst. room) switch
ESTESD12I*DI*1Telescope Room, sliding door side switch

4.12.3 Flap Signals

The flaps have a Siemens absolute encoder with BCD outputs. The selected type will have three or four digits; the hardware can accommodate either type.

FLOPENO*DO*1Flaps open command
FLCLOSEO*DO*1Flaps close command
FLLSOPI*DI*1Flaps opened limit detected
FLLSCLI*DI*1Flaps closed limit detected
FLAUTSELI*DI*1Flaps automatic control selected

4.12.4 Anemometer Signals

Anemometer on Top of Building

WIHMAGIAI*2Horizontal magnitude
WIREFIAI*3Reference value 2.5V
WIVVELIAI*4Vertical velocity
WIDIRIAI*5Wind direction

Anemometer on Telescope Top Ring

TWIHMAGIAI*6Horizontal magnitude
TWIVVELIAI*9Vertical velocity
TWIREFIAI*8Maximal gust (Rafaga)
TWIDIRIAI*7Wind direction

4.12.5 Analog Board Cable


out036yellow.ROPOSOFF? .
ret017green.. gnd
out137gray/pink.. .
ret116blue/red.. gnd
in046brown/gray.WIVVEL? .
ret0414wh./gr... gnd
in027brn/blu.WIHMAG? .
ret0215wh/blu.. gnd
in0321gry.WIREF? .
ret0329pnk.. gnd
. in0123vio.ROPOSERRI .
ret0131blk.. gnd
in0522brn.WIDIR? .
in005red.ROVREFI .
ret0013blu.. gnd
ret1110grn.. gnd
in133brn/pnk.. .
ret1311wh/brn.. gnd
in094brn34TWIVVEL? .
in1026brn/red.. .
ret1034wh/red.. gnd
in1225brn/grn.. .
ret1233wh/grn.. gnd
in068brn/yel25TWIHMAG? .
ret0616wh/yel.. gnd
in0720yel28TWIDIR? .
ret0728grn.. gnd
in0824brn31TWIGUST? .

4.12.6 Rotation Signals

The rotation of the building is controlled by position sensors which sense the angle difference between building and azimuth. This is done in an analog way, so there is a position PI controller in hardware. The hardware enables the building drive signal (RODRENAB) if:

The software can also drive the signal RODRENAB at any time. So, there is an OR function implemented for this signal. For more information about the rotation system, refer to Section 4.6.

ROVREFIAI*12Velocity reference to building drive (test-point for software)
ROPOSERRIAI*12Building position error (test-point for software)
ROPOSOFFOAO*12Building position offset
RODRENABO*DO*1Building drive enable
ROILENABO*DO*1Building interlock enable; this signal switches on the power to the amplifier
ROPIAPOO*DO*1Building PI Controller, apply position offset - i.e. feed signal ROPOSOFF to PI Controller
ROPIRSTO*DO*1Building PI Controller reset
ROWARNO*DO*1Building rotation warning lamps ON
ROIL3DI*DI*1Building interlock, 3 degrees pos. or neg. limit detected
ROILPII*DI*1Building PI Controller interlock
ROPADISI*DI*1Building drive power amplifier disabled
ROAUTSELI*DI*1Building drive automatic control selected

4.12.7 Sliding Door Signals

Take adequate precautions to warn personnel when the door is operated under remote control.

SDOPENO*DO*1Sliding door open command
SDCLOSEO*DO*1Sliding door close command
SDLSOPI*DI*1Sliding door opened limit detected
SDLSCLIDI*1Sliding door closed limit detected
SDAUTSELI*DI*1Sliding door automatic control selected

4.12.8 Slit Shutter Signals

SSSTRTO*DO*1Slit Shutter start command (impulse signal)
SSSTOPO*DO*1Slit Shutter stop command (impulse signal)
SSCLOSEO*DO*1Slit Shutter close direction signal
SSPWONO*DO*1Slit Shutter power on
SSLSOPI*DI*1Slit Shutter opened limit detected
SSLSCLI*DI*1Slit Shutter closed limit detected
SSAUTSELI*DI*1Slit Shutter automatic control selected

4.12.9 Windscreen Signals

The Windscreen has a Siemens absolute encoder with BCD outputs. The selected type have 4 digits.

WSSTRTO*DO*1Windscreen start command (impulse signal)
WSSTOPO*DO*1Windscreen stop command (impulse signal)
WSUPO*DO*1Windscreen up direction select
WSPWONO*DO*1Windscreen power on
WSLSUPI*DI*1Windscreen up limit detected
WSLSDNI*DI*1Windscreen down limit detected
WSLSCHI*DI*1Windscreen chain broken detected
WSAUTSELI*DI*1Windscreen automatic control selected
WSAENCIDI*8Windscreen Absolute Encoder

4.12.10 Interlock Signals

The interlock signals which refer to a certain building subsystem are explained in the appropriate chapter. Note that other emergency stop signals, which were installed later, are described in Subsection 4.12.2 and have the abbreviation ESxxx.

ILEMSTO1I*DI*1Building Emergency Stop button pressed
ILEMCOMI*DI*1Any Emergency Stop button pressed

4.12.11 Miscellaneous Signals

380VPFI*DI*1Building 380V phase failure


This signal schedule describes the location for the VME computer signals of the building. The signals are explained in Section 4.12. This section provides the information to track each signal from the software driver to the input or output of the VME board, and to the building racks.

The VME system for the building contains two Digital I/O interface boards, and one Analog I/O board.

The digital signals are connected via dedicated cable to the Weidmueller Multi-termination strips MTS1 and MT2. From here, the VME outputs to the building racks run via Optotriacs using MTS1. The VME inputs from the building racks are connected via relays, using MTS2. The work station encoder signals are connected via cable from back connector of the encoder Opto-coupler Eurocard rack. This is done without using Weidmueller Multi-termination strips. The analog inputs and outputs are connected to TS3.

4.13.1 Digital I/O ACRO0 (SLOT 9)

SSPWONO*/acro001MTS1-15 B32LOWOPT#16slit shutter power on
SSCLOSEO*/acro011MTS1-13 B31LOWOPT#6slit shutter move direction
SSSTRTO*/acro021MTS1-11 B30LOWOPT#5start move slit shutter
SSSTOPO*/acro031MTS1-9 B29LOWOPT#4stop move slit shutter
WSPWONO*/acro041MTS1-7 B28LOWOPT#15power on windscreen
WSUPO*/acro051MTS1-5 B27LOWOPT#3windscreen move direction
WSSTRTO*/acro061MTS1-3 B26LOWOPT#2start move windscreen
WSSTOPO*/acro071MTS1-1 B25LOWOPT#1stop move windscreen
FLCLOSEO*/acro081MTS1-31 B24LOWOPT#10close flaps
FLOPENO*/acro091MTS1-29 B23LOWOPT#9open flaps
ROWARNO*/acro0111MTS1-25 B21LOWOPT#17warning lamps on (not used)
ROPIRSTO*/acro0121MTS1-23 B20LOWTS2-1 PI resetPI controller reset (not used)
ROPIAPOO*/acro0131MTS1-21 B19LOWTS2-3 to PIapply position offset (not used)
ROILENABO*/acro0141MTS1-19 B18LOWOC1-A2power on building rotation
RODRENABO*/acro0151MTS1-17 B17LOWTS5-7 to PIbuilding drive enable
BSDEFLO*/acro0181MTS1-43 A30LOWOPT#14deflate bottom seal
BSINFLO*/acro0191MTS1-41 A29LOWOPT#13inflate bottom seal
SDOPENO*/acro0221MTS1-35 A26LOWOPT#12close sliding door
SDCLOSEO*/acro0231MTS1-33 A25LOWOPT#11open sliding door
ESTESD12I*/acro0241MTS1-63 A24LOWRelay24emergency button telescope room
ESIRRO11I*/acro0261MTS1-61 A22LOWRelay25emergency button IR room
ESWSRO10I*/acro0281MTS1-59 A20LOWRelay26emergency button windscreen area

SSAUTSELI*/acro0331MTS2-14 C31LOWRelay7slit shutter automatic control selected
SSLSCLI*/acro0341MTS2-12 C30LOWRelay6slit shutter close limit switch
SSLSOPI*/acro0351MTS2-10 C29LOWRelay5slit shutter open limit switch
WSAUTSELI*/acro0361MTS2-8 C28LOWRelay4windscreen automatic control selected
SWLSCHI*/acro0371MTS2-6 C27LOWRelay3windscreen chain broken limit switch
WSLSDNI*/acro0381MTS2-4 C26LOWRelay2windscreen down limit switch
WSLSUPI*/acro0391MTS2-2 C25LOWRelay1windscreen up limit switch
FLAUTSELI*/acro0401MTS2-32 C24LOWRelay13flaps automatic control selected
FLLSCLI*/acro0411MTS2-30 C23LOWRelay12flaps close limit switch
FLLSOPI*/acro0421MTS2-28 C22LOWRelay11flaps open limit switch
ROILPI*/acro0441MTS2-24 C20LOW.building PI controller interlock
ROAUSELI*/acro0451MTS2-22 C19LOWRelay10building automatic control selected
ROPADISI*/acro0461MTS2-20 C18LOW.building power amplifier disabled
ROIL3DI*/acro0471MTS2-18 C17LOWRelay8three degree interlock detected
BSAUTSELI*/acro0491MTS2-46 A2LOWRelay19bottom seal automatic control selected
BSLSDEFI*/acro0501MTS2-44 A3LOWRelay18bottom seal deflated limit switch
BSLSINFI*/acro0511MTS2-42 A4LOWRelay17bottom seal inflated limit switch
SDAUTSELI*/acro0531MTS2-38 A6LOWRelay16sliding door automatic control selected
SDLSCLI*/acro0541MTS2-36 A7LOWRelay15sliding door close limit switch
SCLSOPI*/acro0551MTS2-34 A8LOWRelay14sliding door open limit switch
ESEMRO08I*/acro0561MTS1-55 A9LOWRelay28emergency button EMMI room
ESCORO07I*/acro0571MTS1-53 A10LOWRelay29emergency button control room
ESWSRO09I*/acro0581MTS2-56 A11LOWRelay27emergency button windscreen area
380VPFI*/acro0591MTS2-54 A12LOWRelay23building 380V phase failure
ESCORO06I*/acro0601MTS1-51 A13LOWRelay30emergency button control room
ESBUCO05I*/acro0611MTS1-49 A14LOWRelay31emergency button building control room
ILEMCOMI*/acro0621MTS2-52 A15LOW.any emergency button
ILEMSTO01I*/acro0631MTS2-50 A16LOW.building emergency stop button

WSAENCI/acro001encoder B32HIGHwindscreen absolute encoder
WSAENCI/acro011encoder B31HIGHwindscreen absolute encoder
WSAENCI/acro021encoder B30HIGHwindscreen absolute encoder
WSAENCI/acro031encoder B29HIGHwindscreen absolute encoder
WSAENCI/acro041encoder B28HIGHwindscreen absolute encoder
WSAENCI/acro051encoder B27HIGHwindscreen absolute encoder
WSAENCI/acro061encoder B26HIGHwindscreen absolute encoder
WSAENCI/acro071encoder B25HIGHwindscreen absolute encoder
WSAENCI/acro081encoder B24HIGHwindscreen absolute encoder
WSAENCI/acro091encoder B23HIGHwindscreen absolute encoder
WSAENCI/acro0101encoder B22HIGHwindscreen absolute encoder
WSAENCI/acro0111encoder B21HIGHwindscreen absolute encoder
WSAENCI/acro0121encoder B20HIGHwindscreen absolute encoder
WSAENCI/acro0131encoder B19HIGHwindscreen absolute encoder
WSAENCI/acro0141encoder B18HIGHwindscreen absolute encoder
WSAENCI/acro0151encoder B17HIGHwindscreen absolute encoder

4.13.2 Analogue I/O

ROPOSOFFO/aio0OUT-0TS3-1,2,3 A31-C31building position offset (not used)
ROVREFI/aio0IN-0TS3-7,8,9 A1-C1velocity reference
ROPOSERRI/aio0IN-1TS3-10,11,12 A3-C3building position error

4.13.3 RS232

ACRS232RS232Connected to RS232 interface of VME CPU

4.13.4 I/O Boards Jumper Settings

ACRO 9481J1, J3, J5, J7Installed Enables internal pull-up to +5V of the I/O lines
J2, J4, J6, J8InstalledEnable internal threshold reference of the input
J17Base address:Base address:
board 1; 5-6 installedffff1000 hex (/acro0)
board 2; 1-2 and 5-6 installed ffff1400 hex (/acro1)
J19InstalledShort supervisory and non-privileged access
J20OmittedSYSFAIL is not asserted after reset
VMIC, VMIVME-3111, analog I/ODefault setting is: analog inputs; 16 differential, -10 to +10V
analog outputs; single-ended, -10 to +10V
J1InstalledGround P3 return
J2InstalledGround P3 sense
J3Omitted5V full scale input
J41-1 installedBipolar analog inputs
J52-3 installedAuto input gain adjust
J6OmittedUnipolar analog inputs not enabled
J7, J8OmittedOutput test is validated
J9, J10, J11OmittedP3 inputs enabled
J121-2 installedBipolar analog outputs
J13Omitted20V full scale output range
J151-2 installed20V full scale input range
J17 to J24OmittedDifferential input
J27 to J34OmittedDifferential input
J25Omitted2.5Vdc reference unused
J26Installed10Vdc reference used
J35InstalledGround P2 sense
J36, J37Base address:Base address:
board 1; J36: 0, 1, 2, 3, 6 and 7 installed ffff30000 hex (/aio0)
J37: 0, 1 and 2 installed
J37-3Omittedshort non-privileged access
J382-3 installedAuto input zero adjust
J39InstalledGround analog outputs return
J40Omitted5Vdc reference unused
J41OmittedExt. trig not connected to P2 ground sense
J421-2 installedExt. trig rt. connected to P2 ground sense


This section lists maintenance information for the NTT building VME rack; also included is a List of Drawings and Data Sheets.

4.14.1 Interlock Chain

A special sheet is added in the drawings which shows the schematic diagram of the interlock chain in relation to the azimuth interlock and the emergency stop chain.

4.14.2 Connections to Building Power Racks

The interfacing to the building power racks has been designed to ensure complete galvanic isolation between VME rack and power racks. This is done to avoid interference from the thyristor power amplifiers.

Care must be taken during maintenance to avoid any galvanic connection between the two systems via cable shields etc. Treat the velocity reference to the building rotation power amplifier with special care when taking measurements etc.

A special cable duct in the VME rack has been mounted in order to guide the cables to the building power racks with a minimum of interference to the VME computer.

4.14.3 Drawing List

Building Position PI Controller.. CS-P-1495
- Schematic Diagram (Sht 1) 126-06-88.
- Schematic Diagram (Sht 2) 230-06-88.
- PCB Layout . .CS-P-1495A
Isolation Amplifier..CS-P-1494
- Schematic Diagram . 25-07-88.
- PCB Layout . .CS-P-1494A
Building Control VME Rack Schematic Diagram. .CS-E-1525
- Interlock Chain 1 27-04-89.
- Digital I/O 2 18-05-88.
Building Control VME Rack Wiring Diagram. .CS-E-1526
- Relay Inputs Part 1314-03-90 .
- Relay Inputs Part 2414-03-90 .
- Position PI Card Controller 514-03-90.
- VME Analog I/O Cable614-03-90 .
- Interlock Chain 7 14-03-90.
- Miscellaneous Signals814-03-90 .
- Layout of Rack Front 914-03-90.
- Layout of Rack rear 10 14-03-90.
- Emergency Stop Switches 1107-05-90.
Building Control VME Rack, Encoder.. CS-E-1540
- Schematic Diagram 1 14-03-90.
- Cabling Diagram 2 02-04-89.
- Line Driver, Schematic Diagram 307-07-88.
- Line Receiver, Schematic Diagram 413-03-90.
- Line Driver, PCB Layout ..CS-P-1516A
- Line Receiver, PCB Layout ..CS-P-1517A
Slit Shutter Speed Guard Circuit (Sht 1)1 ..
Slit Shutter Speed Guard Circuit (Sht 2)2 ..
Slit Shutter Speed Guard Board.. .

4.14.4 Data Sheets

Burr-Brown Opto-transceiver LDM802
Siemens Absolute Encoders6
Burr-Brown Isolation Amplifier 36508
Burr-Brown DC/ DC Converter PWR 3172
Hottinger Baldwin Position Sensor W50TS11
Hottinger Baldwin Measuring Amplifier MGT 233.011