Mechanism Moves. (Network 101 commands)
As with ISIS the LOCAL command which is shorthanded to "|" will return :-
Enter Emsg
This will allow 101 commands to be entered only, NOT status requests in the form of a 200 messages.
Therefore by typing, say APD101(0) <cr>
Will move Aperture wheel detent out.
Mnemonic: FPW 1 - 8
..................APW 1 - 8
..................PPW 1 - 8
..................ETW 1 - 6
Note: That positions 3 & 6 are used for calibration.
Wheel moves depend upon the associated detent being in the correct position ie. "out". Wheel moves are interlocked when the detent is "in". When the detent is withdrawn the wheel motor is also powered on at stall so that should the wheel be unbalanced it will not creep out of position. The network then will send down the move parameter and the wheel move will complete. Five seconds is allowed to elapse with the motor at stall again to allow sufficient time for the detent "in" command to drive the detent back into the wheel.
The disadvantage with this method is that the wheel cannot be moved by hand with the detent out.
This problem will be addressed in version 1.2.
Parameter range 0 = out
..........................1 = in
The electronic drive system takes care of the action of these mechanisms. The 4MS can only set the address and allow time (5 secs.) for the move to complete.
The detent status task reads the actual micro switch positions of each detent which is shown in the 3datum field of the status return. These values are not used within ICL procedures and are for reference only.
Valid positions :
Detent "in" ..................................3datum = 6
Detent not engaged correctly ......3datum = 2
Detent "out" ...............................3datum = 1
All other values are fault values.
Parked .........................-1
Degrees ........................0 - 100 degs. (00.0 - 10.0 degrees)
Therefore an angle of 3.7 degrees is given in the parameter field as 37 and shown as 37 in the status fields.
Zero degrees is a valid position with the mechanism in contact with the tilt arm. This and all other degree positions releases its interlock in the mechanism shutter interlock task. The FPD interlock will not be released and subsequently a wheel move cannot action until the tilt is back into the "parked position". ie. at -1.
Parameter range 0 - 6000 microns
Sets a mechanism shutter interlock when moving.
Parameter range: 10 - 150 mm
Sets a mechanism shutter interlock when moving.
Status 0 = open
...........1 = close
ldatum 0 = No detector connected.
............1 =IPCS
............2 =CCD
This mechanism cannot be opened directly from 4MS or a network command. It can though be closed through interlocks. This facility is linked with the door interlock overrides DIL, which is set to value 0 on start-up. All mechanisms have to be Initialised and in defined positions before the mechanism interlock to shutter is released within 4MS and allows the shutter control module to open the shutter on a command from the IPCS.
Whilst the shutter is open all mechanism movements are interlocked out, and if an inspection door is opened the shutter is closed immediately.
If the IPCS camera is fitted then the above interlock MUST be satisfied within the shutter control module (SCM).
To this end a help screen is available which lists the interlocks that have to be cleared before the shutter control module is able to open the shutter.
Type : IPCS for help screen.
Each time this help screen is called it is updated and shows only those interlocks that have to cleared.
This interlock does not apply when the SCM is connected in CCD mode, even though a mechanism error could show that an interlock was still set.
It is good practice to clear all these interlocks as if it was an IPCS camera therefore insuring that mechanism positions are properly defined.
How the DIL facility effects the shutter is further discussed under its own heading.
Parameter range 0 = valve open
..........................1 = valve close
These two commands open or close the nitrogen inlet and outlet valves and flush the etalon cavity.
Both valves use the same hardware address which is bit masked to operate each valve.
There is no genuine hardware return on these valves to ensure their correct operation. 3datum therefore displays the binary number that is at the address.
Therefore
0 = both valves closed
1 = Inlet valve open only
2 = outlet valve open only
3 = both valves open
Status returns. (Network 200 commands)
Do not use any 200 commands from the operator port with the "|"command as the 4MS is not able to write back to the terminal in
the correct form, it may hang the system.
These can only be seen as a six field string when a terminal is connected to the Utility Network NIU, and is logged on as a user with
the standard MON101(1) MON200 commands.
At the operator port of the 4MS one is able to access the status of each mechanism and CS100 status.
Using the Mnemonic for the mechanism or function followed by the Forth word SEE will display the eleven fields and their contents
in an ordered form.
ie. FPW SEE Will display the current status of the Focal plane filter wheel.
The six fields are as follows :-
Cmnd errs (hex) .................Mechsm errs (hex)
Temp errs (hex) .................804 Flag (hex)
Operations (hex) ................Status reqs (hex)
Target (dec) .......................Position (dec)
ldatum (hex) ......................2datum (hex)
3datum (hex)
Operations
Defined within the 4MS Kernel are as follows.
0 =No operation.
1 =Immediate status request (200)
2 =Delayed status request (201)
8 =Initialise (102)
10 =Move (101)
20 =Stop (100)
The above are normally displayed during an operation and show current state of that operation.
If an interlock has been set against the particular mechanism or function then this will displayed in the same field without the
operation being actioned. The Kernel will have rejected the operation because of the interlock.
Knowledge of what mechanism sets what interlock can be sometimes difficult to determine. So a table of set and clear
interlocks is being prepared and will be issued with Vl.2.
There are 5 interlocks that could be shown in this field.
Interlocks 1 & 2 are mechanism interlocks
.................4 & 40 are CSl00 interlocks
and ..........5 is an interlock on mechanisms because the shutter is open.
Target :
Target repeats and retains the parameter that was sent originally.
Parameter:
Parameter will be updated from target at the end of the move. This will occur even though the mechanism may not
have achieved the desired target.
Because of the limited encoding facilities on most of the mechanisms, especially the filter wheels a compromise had to be found that suited all.
ldatum, 2datum, 3datum
Each of these fields will contain different information for each Mnemonic. Document 2.44 describes each in detail. The 3datum field is generally left for a hardware return that can be directly read as in the case of detents and shutter mechanism.
Status only functions
Some Mnemonics offer status returns only t the request of a network 200 command. (or a SEE command at the
operator terminal)
A 101 network command will be interlocked out as an "invalid function" in the Cmnd errs.
Therefore the following Mnemonics have a status only function. Some pertinent points arising from each one is also included.
Parameter 0 = door open
.................1= door closed
The last four fields of the status array are assigned one to a door. Thus :-
Position = Focal plane wheel door
ldatum = Aperture wheel door
2datum = Pupil wheel door
3datum = Etalon wheel door
The monitoring of these four doors is to make sure they are closed and locked. Thus clearing one of the interlocks that prevents the shutter from being opened with IPCS.
If a door is opened whilst the shutter is open then the shutter will close immediately.
Parameter 0= shutter open
.................1 = shutter closed
This has been discussed in an earlier section.
For TMP The focal plane temperature is written to Position. The etalon temperature is written to ldatum.
The external temperature is written to 2datum.
The focal & etalon temperatures are compared with the external temperature and checked against a limit. If the limit of +5 degrees is exceeded then an error code of either 18 (hex) or 19 (hex) is written to Mechsm errs .
For NPR The Etalon cavity pressure is written to Position. The external pressure is written to 1datum
The Etalon cavity pressure is compared to the external pressure
and if it exceeds 10 mbars then an error code of 1B (hex) is written to Mechsm errs.
CS100 Control System :
Upon power up the CS100 software is preset to known values.These values are listed with each command, in document 2.44.
This document gives a clear guide to the limits that apply and the function of each mnemonic. These mnemonics are listed below and their page no. for reference (see Taurus Quick Reference Guide).
.............................Page No.
CAL, CSC .............6
CSG, CSI, CSL .....7
CSR, CST .............8
CSV, CSX ............9
CSY, CSZ ............10
GAP .....................15
NOS .....................16
RMP ....................18
RUN ....................19
STP, STR ............20
Parameter 0,1,2
This is dealt with separately because it must be understood how each override effects the operation of mechanisms and the shutter.
These interlocks apply when the shutter Control Module (SCM) is switched and connected to an IPCS detector. The interlock provided by the 4MS and in fact the A & G box have to cleared before the IPCS can open the shutter.
When the system powers up the override level is set to zero which provides the safest level of interlocking. Level 0,1 & 2 can be set with a DIL101(n) command in the usual way.
The difference between levels 0 & 1 is that in level 1 mechanisms are allowed to move with the shutter open but doors must be closed.
Level 2 is at present still available to the user and must be used with extreme care. This overrides all interlocks including
those set up in hardware, so doors and or mechanisms can be operated with the shutter open.
Used mainly for off telescope optical alignment work.
INS, MON ....................Page 22 2.44 Document
RES............................... page 23
Monitor mode is the most commonly used standard function as this must be implemented by any node wishing to receive updated status from the Taurus system.
Two functions HMS & NET have not been included.
Problems Noted
Four problems have been noted during the commissioning of this network software. They are offered here for comment. One is
certainly known about from previous history.
a) Unreliable location in positioning of pupil wheel. Seems particularly subject to low temperatures.
b) If either the Focal plane wheel or Aperture wheel has to go to location 7 via the encoder index point they will generally miss position. All other locations + index are satisfactory.
Finding location 7 without an index move first works well.
c) Noted sometimes that a detent will drive in and out continuously. This rarely happens if the system has been powered up correctly, but can happen if one of the racks main supply is interrupted leaving the drive cards in an unstable state. Solution is to power system down and power all on together.
d) Because of filter wheel creep when the detent is removed and the telescope is set away from the zenith a modification has been added to this version (V1.11) to apply motor power as the detent is withdrawn and hold the wheel at stall. Then the wheel is driven to its new position and the detent replaced, motor power off. It does no harm to leave the motor at stall although it should be avoided for long periods because of the possible heat generated. Another disadvantage is that the wheel cannot be turned by hand as all efforts will be resisted by the motor which returns the wheel to its original position.
It is expected that this problem will be overcome in Vl.2.
Many improvements in mechanism control and interrupt handling have been included.
-------------------------------------------------------------------
Release : Vl.2
Date : 8/5/91
Location : WHT La-Palma.
Specification : WHT Taurus Network Messages Version 3.0
-------------------------------------------------------------------
Previous release : Vl.ll
Date : 7/2/91
Location : WHT La-Palma.
Specification : WHT Taurus Network Messages Version 2.44
-------------------------------------------------------------------
This document highlights the Important changes to the Taurus 11 software. These changes Instigated from work done during the commissioning period In Jan/Feb 1991, and In consultation with Mr.. S.Unger & Mr. M.Johnson supersed Vl.ll.
Wheel and detent sequencing.
Detent status shown In wheel status.
Interlocks on Tilt removed except when (FPW) is moving.
Three additional mechanism error codes.
Revised method of calculating step (STP) value.
Instrument status fields Increased to include the version no.
Sealed vocabulary through operator port.
Help screen displaying IPCS shutter interlocks.
Detent mnemonics APD, FPD, ETD & PPD have been removed from the mnemonics library which means there Is no longer separate network commands to operate each detent.
The operation of the any detent is now taken care of by the 4MS on receipt of a valid wheel move command.
For example a network command APW101(x) (where x -8 to +8) will move the detent out holding the wheel at stall until the datent Is fully out, then turn the wheel to position 8. If the parameter is positive then the detent is returned back into the 'wheel to complete the move. If the parameter is negative then the .detent Is left out to complete the move. In this case the motor will be switched off so that the wheel can be turned by hand and Is left unzeroed. Therefore the next wheel move will be via the encoder index.
A zero parameter Is accepted by the 4MS but has no action on ,any wheel or detent.
To complement this wheel and detent sequencing the network status string for each wheel mnemonic Is as follows, consisting of six fields.
(command errors, mechanism errors, wheel position, detent position, 0, detent engineering status)
OR (eec, eem, aw, ad, 0, es)
The wheel position field (aw) is always returned as a positive number.
The Focal plane filter wheel is slightly more complicated because of the associated filter tilt mechanism. (FPT)
For this filter wheel to move satisfactorily the tilt mechanism must be first driven to the "parked" position. The 4MS does not drive the tilt to parked as part of the sequence move and relies upon a FPT101 network command prior to the wheel move. The 4MS will however prevent the filter wheel move with a mechanism error code of 0D hex until the tilt Is correct.
It Is possible to park the tilt mechanism (FPT) irrespective .of wheel or detent position and is interlocked only whilst the wheel is moving.
Should any detent fail to disengage from Its wheel during a sequence move then the move is rejected at that point and a mechanism error code 0E hex is returned.
The other error code associated with detents (0A hex) is returned If the detent fails to engage correctly back Into the wheel on Issue of a positive move parameter only.
The Etalon wheel parameter range is -6 to +6 .
All the others are -8 to +8 .
If it is required to move the detent out without moving the wheel afterwards then the present wheel position is sent as a -,negative number.
The only change to the CS100 operation has been in the way the 4MS stores a new step value. A mechanism error code of lC hex is ,returned If the step demand Is greater than the 4MS calculated value after receipt of a CAL101 and associated commands.
Instrument status has been expanded to four fields. The new forth field contains the software revision no. ie. 78 hex.
A sealed vocabulary has been added which will not effect any of the network commands, but will limit the operator port to essential words only. The system powers up sealed but can be returned to normal Forth vocabulary by using the word UNSEAL.
The system has been left In EPROM and tested for correct start-up and system responses.
Documentation provided
This has been provided in the form of a technician guide which covers the systemls response to such situations as power-up, initialising, mechanism moves, CS100 controls, network commands and status responses.
The Taurus network document V3.0 which has been used as the ease for this software revision is availble to the Technicians and --should be used In conjunction with the tech-guide.
Backups provided
A note covering the load sequence of the three source disks is available, as well as a precompiled version. Also a spare set of EPROMs to Vl.2
Known problems
None reported.