Its purpose is to provide an interface between the WHT system computer and the following mechanisms:
The Aperture Wheel
The Filter Wheel
The Grism Wheel
The Focus Mechanism
In addition, facilities are provided for controlling the door locks (normally under the control of the system computer) and the shutter (normally under the control of a CCD or an IPCS controller).
2 6Ux360 subrack side-panels
2 6U front mounting flanges
5 Top-f ront tie bars
5 Bottom-front tie bars
2 Top-back tie bars
2 Bottom-back tie bars
2 DIN connector mounting rails (shortened to 10cm approx)
1 Hinged panel
1 Four-hole connector panel (custom)
1 Seven-hole connector panel (custom)
1 Three-hole connector panel (custom)
1 Five-hole connector panel (custom)
26 160mm card guides
4 220mm module guides
Top row, holes 1 & 3, facing forward
Top row, holes 12 & 14, facing forward
Top row, holes 27 & 28, facing backward
Lower middle row, holes 1 & 3, facing forward
Lower middle row, holes 27 & 29, facing backward
The top-back tie bars should be located as follows:
Top row, holes 23 & 23, facing backward
Lower middle row, holes 17 & 19, facing backward
The bottom-front and bottom-back tie bars should be located in the upper-middle and bottom rows, so as to mirror the tie bars in the top and upper-middle rows.
The hinged panel should be attached as the upper front panel. The lower front panel consists of the four-hole connector panel (on the left), the seven-hole connector panel (in the middle) and the power supply module (on the right). The upper back panel is the three-hole connector panel. The lower back panel is the five-hole connector panel. It is recommended that none of these be attached until the wiring is complete.
The card guides are placed in the upper half of the rack, and the module guides in the lower half. Each guide has two possible orientations: the slot that takes the card may be on the left or on the right.
Two of the card guides have the slot on the right, and are located as a pair on position 58. The other twenty four have the slot on the left, and occupy positions 10, 13, 16, 19, 22, 25, 28, 31, 34, 37, 40 and 43. The module guides also have the slot on the left, and occupy positions 62 and 82.
The DIN connector mounting rails are fixed onto the top and bottom back tie bards, immediately behind the bottom right of the module guide rails.
1 CPU card
1 Bus Buffer Interface card
1 Memory expansion card
1 GPIB Interface card
1 Serial Interface card
1 Analogue/Digital Converter card
3 Rotary Encoder cards
1 Parallel Interface card
1 Shutter Control card
1 Stepper Motor Driver Module
1 Power supply module
1 100W 22R resistor
1. GPIB Interface card
2. Serial Interface card
3. (slot vacant)
4. Analogue/Digital Converter card
5. Rotary encoder card #l
6. Rotary encoder card #2
7. Rotary encoder card #3
8. CPU card
9. Bus Buffer Interface card
10. Memory expansion card
11. Parallel Interface card
12. Shutter Control card
The Stepper Motor Driver Module is held in place by the card guides to the right of the backplane, while the power supply module is held in the module guides at the bottom right of the rack. The power supply module should not be inserted until the cable harness is in place.
Supplier: Syntel
Designation: SYN MPO9
Crystal: 4MHz
PROM: Map 5
ROM: Forth v2 18-7-87
Links: as supplied
Additional documentation: SYN MPO9 User Manual (part of 4MS System Manual)
3.3.2 Bus Buffer Interface Card
Supplier: RGO Electronics Group
Designation: 4MS-BBI WEM002
Link JL1: connect 6-19,10-37,13-26 (purpose unknown)
Link JL2: connect 1-2 (to enable watchdog timer)
Additional documentation: 4MS-BBI User Manual (part of 4MS System Manual)
3.3.3 Memory Expansion Card
Supplier: RGO Electronics Group
Designation: Unknown
This board can be configured to support either four 8K SRAMs or four 8K EPROMS. An additional SRAM or EPROM is located on the CPU card.
Additional documentation: None
3.3.4 GPIB Interface Card
Supplier: Syntel
Designation: SYN I488
Switch SW1: set to Off, Off, Off, On, Off, Off (purpose unknown)
Switch SW2: set to Up, Up, Up, Up, Up, Up, Up, Down (purpose unknown)
Additional documentation: SYN I488 User Manual (part of 4MS System Manual)
3.3.5 Serial Interface Card
Supplier: Syntel
Designation: SYN ACM3 User Manual (part of 4MS System Manual)
Require port I configured as RS422, ports 2 and 3 as RS232
lCs: U15, U17 and U20 present, U14, U18 and U21 absent
Link Jl: connect 1-2, 3-4, 5-6, 7-8, 9-17-19,13-14,15-16 (port 1=RS422)
Link J2: connect 1-2, 5-6, 9-10, 13-14, 17-18-21-22 (port 2=RS232)
Link J3: connect 1-2, 5-6, 9-10, 13-14, 17-18-21-22 (port 3=RS232)
Link J4: connect 2-3-4-5 (port 1=RS422)
Link JS: connect 1-2-3-4-5 (port 2=RS232)
Link J6: connect 1-2-3-4-5 (port 3=RS232)
Link J7: no connection (purpose unknown)
Link J8: no connection (purpose unknown)
Link J9: no connection (purpose unknown)
Link J10: conned 2-3 (purpose unknown)
Link J11: conned 2-3 (purpose unknown)
Link J12: conned 2-3 (purpose unknown)
Link J13: connect 1-3-4-5 (purpose unknown)
Dil switch: set to On, On, On, On, On, On (to set base address to DC00)
Additional documentation: SYN ACM3 User Manual (part of 4MS System Manual)
3.3.6 Analogue/Digital Converter Card
Supplier: Syntel
Designation: SYN ADC2
Link J1: connect 1-3 (select 0-10V input range)
Link J2: connect 1 -2, 3-4 (select 0-10V input range)
Link J3: undefined (not used, purpose unknown)
Link J4: undefined (not used, purpose unknown)
Link J5: connect 1-2 (purpose unknown)
Unlabelled link: no connection (purpose unknown)
Dil switch: set to Off, Off, On, Off, On, On (set to base address DC70)
Additional documentation: SYN ADC2 User Manual
3.3.7 Rotary Encoder Card #l
Supplier: Gespac
Designation: GESINC-1
Link Jl: connect 1-2 (enable protective ground)
Link J2: connect 2-3, 4-5 (select power from backpiane)
Link J3: connect 2-3, 4-5 (select power from backplana)
Link J4: connect 1-12, 3-10, 5-8 (select single-ended inputs)
Link J5: conned 1-2 (select phase A active high)
Link J6: connect 1-2, 4-5 (select phase B and TOP0 active high)
Link J7: no connection (disable interrupts)
Link J8: connect pairs 1, 2, 3, 5, 6 and 7 (set to base address DC40)
Additional Documentation: GESINC-1 data sheet
3.3.8 Rotary Encoder Card #2
As above, except
Link J8: connect pairs 1, 2, 3, 5, 7 (set to base address DC50)
3.3.9 Rotary Encoder Card #3
As above, except
Link J9: connect pairs 1, 2, 3, 6, 7 (set to base address DC60)
3.3.1 0 Parallel Interface Card
Supplier: Gespac
Designation: GESPIA-2A
Link Jl: connect 1-6 (makes +5V present on output connectors)
Link J2: no connection (disables watchdog)
Link J3: no connection (disables watchdog interrupts)
Link J4: no connection (disables PIA0 interrupts)
Link J5: no connection (disables PIA1 interrupts)
Link J6: connect 1-1 4, 4-11, 5-10, 6-9, 7-8 (set to base address DC30)
Additional documentation: GESPIA-2A data sheet
3.3.1 1 Shutter control card
Supplier: Durham University
Designation: none
Link Jl: no connection (no pull-up on reset line when connected to backplane)
Additional documentation: Shutter Control Card User Manual
(includes circuit diagram, board layout, PCB mask and parts list)
Supplier: Royal Greenwich Observatory
Designation: SMDM
3.4.2 Power supply module
Supplier: Durham University
Designation: none
This module contains two separate power supplies: one to provide +SV, +12V and 12V to the 4MS system, and one to provide an additional +15Vand 15V for the SLVC signal conditioner.
Its current ratings are: 8A "5V, 3.5A @ 12V
Connection to the rack is by means of an 'H'-type connector (RS 481-960), with pins as follows (numbered from the top of the module):
1 Earth
2 240V Neutral
3 240V Live
4 0V
5 0V
6 +5V
7 +5V
8 +12V
9 12V
10 +15V
11 15V
12 N/C
13 N/C
14 N/C
15 N/C
The 0V line is internally referenced to earth via a 100R resistor. There have been some problems with the +5V supply on the backplane being too low. These were dealt with by (a) using multiple pins connected in parallel on the 0V and +5V lines and (b) by adjusting the power supply so that it actually generates between +5.10V and +5.15V. By the time this reaches the backplane, it should be around +4.9V under full load, but it is still well within the TTL supply range under no load. A better solution if the controller were ever upgraded would be to use a power supply with a sense line.
The front panel of the power supply module has five LEDS, one for each power line. The upper row corresponds to the positive rails, the lower row to the negative ones. 5V is red, 12V is green, 15V is orange. There is a rotary switch to disable the LEDs during observation to minimise scattered light.
Internally, the power supply module consists of a Verospeed XL80-4601, which supplies ±5V and ±12V (the 5V signal is not used), together with a simple dual-rail linear supply to provide ±15V. The 0V lines of these two supplies are connected together. The pinouts of the XL80-4601 are (looking at the edge of the board, left to right):
3-way Molex:
1................ 24OV Live
2 ................24OV Neutral
3................ Earth
12-way Molex:
1................ 5V
2............... 12V
3............... +12V
4............... +12V
5................0V
6................0V
7................0V
8................0V
9............... +5V
10 ............+5V
11............ +5V
12 ............+5V
The pinouts for the custom ±15V supply are (looking at the relevent edge of the board with the transformer on the upper side of the card, from left to right):
3-way Terminal Plug:
1 .................240V Live
2................. 240V Neutral
3................. Earth
4-way Terminal Plug:
1 ................0V
2................ N/C
3.................15V
4.................+15V
The internal connections to the switch are as follows (looking at back of switch, numbering from top left to bottom left to bottom right):
1................ N/C
2................ Common (0V)
3 ................Switched 0V #l
4................ Switched 0V #2
5................ Common (0V)
6 ................N/C
Finally, the connections to the LED circuhboard attached to the front panel are (looking at the back of the board, numbering from left to right):
3-way Molex:
1 .....................0V (Switched)
2 .....................12V
3 .....................15V
5-way Molex:
1 .................0V (Switched)
2 ..................+12V
3 ..................+5V
4 .................+15V
5 .................N/C
3.4.3 100W 22R Resistor #l
This is mounted in the middle of the lower had of the left hand side panel (behind the military connectors on the front panel). It is connected to the shutter control card, and is used to limit the heat dissipation in the shutter solenoid.
3.4.4 100W 10R Resistor #2
This is also mounted in the middle of the lower had of the left hand side panel. It is connected between the +12V and 0V power supply lines on the backplane, and is used to ensure that the power supply operates within spec. (The power supply must be loaded to at least 25% capacity on both the +12V and +5V lines. In the case of the +12V line, this means 25% of 3.5A).
3.4.5 Manual Control Handset
This is connected to the front panel of the local controller via a 6-way Lemo plug/socket.
The following functions are provided by SPST rocker switches: Open Shutter, Open Door.
The following functions are provided by SPST rotary switches: Shutter Interlock Override, Wheel Interlock Override.
Earth: Yellow/Green
240V Live: Red or Brown
240V Neutral: Black or Blue
+24V: Red or Brown
24V: Black or Blue