UIST Cryostat Control Software

Contents:

• UIST CCS in CVS
• Overview of UIST CCS
• Instructions for Loading and Running the CCS
• Calibration of Datum Switch Position

Links to other pages:

• UIST CCS Mechanism Testing
• UIST CCS Mechanism Reports

UIST CCS in CVS

> cvs checkout uistCCS

This produces the following directory structure:

uistCCS/
	README
	capfast/README
	config/
	data/README
	db/README
	dl/README
	motor4_3Rec/
	src/README
	startup/README

Software documentation can be found by following the above links to the README files.

The README in the toplevel directory also contains build instructions.

Please note that the READMEs are designed to be read in conjuction with comments contained within the files they document.

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Overview of UIST CCS

• datum
• accept request to move to target position
• report when a move is complete
• report errors

• circular, non limited travel
• linear, limited travel

The UIST CCS uses a similar combination of Gemini CAD (Command Action Directive), CAR (Command Action Response) records and SNL (State Notation Language) to control mechanism movement as used by Michelle. Each mechanism has 1 CAD and CAR record. However, Michelle uses a different SNAM (subroutine name executed when the CAD record is processed) for each of its mechanisms, UIST has 1 SNAM to control mechanism motor movement. It is called motorCadSnam() and the source code is in src/mechanism.c. Michelle also uses different SNL programs to control each of its mechanisms, UIST uses 1, called mechanism_st, the source code is in src/mechanism_st.st.

The movement of individual mechanisms is customised using EPICS database records. The values of the records are used by the SNL to decide how the mechanism should be moved. The record values are loaded at startup from PV load .data files (each mechanism has its own file). The file sets values in various records including; motor record (eg. limits, velocity, backlash, etc.), records that store information about datum switch position and values used during datuming (eg. datum switch to be used for datuming, datuming velocity, initial number of steps to use in incremental search for switch, etc.). The PV load .data files are in the data/directory.

Each mechanism also has a cruLib .data file containing information about target name position and their corresponding step position. These are also loaded at startup and are in the the data/ directory.

For more detailed information on the CCS please see the individual READMEs contained in the uistCCS CVS module and linked to in UIST CCS in CVS of this document.

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Instructions for Loading and Running the CCS

Loading CCS

When the crate is powered on or rebooted the processor automatically runs the uistCCS startup script (see statup/README) to load and start the software. To view the startup process use the CCS serial console button on the uistMenu interface, see section Running CCS below for information on how to start the interface.

Once the startup script has finished the crate can be accessed across the Ethernet using telnet or rlogin, eg:

• > telnet uist-ccs

To restart the system, use the vxWorks command reboot and the system will be reloaded.

Running CCS

1. ensure you source the uist/etc/cshrc script and issue the command baja to setup the correct environment for running UIST software.
2. Note for users doing development work, ie. editing files and recompiling CCS or Edict software, non-development users can ignore this step. At the ATC the vxWorks images used by the CCS and Edict are in different directory trees, for this reason an additional command has to be used to setup the correct vxWorks environment. Logging in as user uist by default sets the environment required for Edict development work, if your work involves development for the CCS use the command 68k on the xterm where the work will be carried out. Use the command baja to return to an Edict development environment.
3. use the following command to start a menu with buttons giving access to DM screens, processor serial ports, etc.:
   • > uistMenu &

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Calibration of Datum Switch Position

Circular Mechanism

Procedure:

1. Start UIST CCS Engineering DM screen:
   > dm uistCCS_eng.dl &
2. Start individual mechanism DM screen using the related display button of the mechanism, eg. Filter Wheel 1
3. Start your favourite editor and open the current CCS Log file, the current file in use can be found by using the following command at the CCS processor prompt:
   uistCCS-> elgReport
   the following command can be used to put a reference mark in the file:
   uistCCS-> elg "\n\n\n filt1: Start of Filter Wheel 1 datum switch calibration\n\n"
4. Force the mechanism to datum using switch 1 and remain at datum position:
   1. On the individual mechanism DM screen switch the Datum Force button to true
   2. Push 1 on the Select Switch button
   3. In Target name text entry box enter 0 (this will ensure the mechanism remains at the datum switch after datuming has completed)
   4. Press the START button to begin the datuming process
5. Now datum on switch 2 by doing the following:
   1. Switch Datum Force button to true
   2. Push 2 on the Select Switch button
   3. In Target name text entry box enter the current step number used as the position of datum switch 2, this can be found in the mechanism's pvLoad .data file by searching for the string "datum2PosLo", alternatively at the CCS processor command line prompt use the following commands:
      uistCCS-> dbgrep "*datum2PosLo" will return a list of records containing datum switch 2 position for each of UIST's mechanisms
      uistCCS-> dbpr "uist:ccs:filt1: datum2PosLo" changing the record name in quotes of this command to the mechanism being calibrated will display the current step number of datum switch 2 in the VAL field
   4. Press the START button to begin the datuming process
6. On the top level UIST CCS Engineering DM screen press the Log Flush button
7. Refresh the editor looking at the CCS Log file, eg. in emacs revert the buffer, so that all data written during the datuming prosess is contained in the file
8. Record the RBV value of the step at which datum switch 2 was found. This will be towards the end of the log file on a line that has the following format:
   Datumed, switch found with 1 step movement, RBV = 24481.0
9. Repeat steps 4 to 8 another nine times in order to calculate an average RBV value at which datum switch 2 is found. This is the step position of datum switch 2 relative to datum switch 1. The repeating of these steps can be done using an engineering exec loaded and run using the tcl/tk engineering interface.
10. Update the mechanism's pvLoad .data file, instructions for doing this are in data/README (link to this file is in section UIST CCS in CVS). The value to change is the figure loaded into the datum2PosLo record, eg:
    long uist:ccs:filt1:datum2PosLo = 24480;
    Note that records used by both Filter Wheels and both Grism Wheels are in the same file, ensure that the record changed belongs to the correct wheel, eg. the above record belongs to Filter Wheel 1 and will only affect the behaviour of this wheel

Linear Mechanism

A linear mechanism's movement and relation to end stops and datum switches is shown in the the diagram below.

HSLE	|		D1		D2		|	HSHE
	|	<------------------ Range of Travel ------------------>					|
	|		/\		/\		|
	|	<- D1 closed ->	:	<- D1 & D2 open ->	:	<- D2 closed ->	|
Step 0

HSLE	Hard Stop Low End of travel
HSHE	Hard Stop High End of travel
D1	Datum Switch 1
D2	Datum Switch 2

The low end of travel is defined as step 0, what needs to be found is the step number at which D1 transitions from closed to open with a single step movement when moving in a positive direction, ie. towards the hard stop at the high end of travel. This step will be defined as the step position of datum switch 1.

The only way to position the mechanism at the end stops is under visual control, therefore the following procedure is carried out while the instrument is warm and the mechanism datum switches and hard stops can be seen.

Note Uist's motors are specially prepared for working at cryogenic temperature, for this reason the motor movement should be kept to a minimum while the instrument is open, alternatively a motor which has not been cryogenically prepared should be used to replace the normal operating motor.

The mechanism must be moved under direct control instead of using the normal control software, the normal control software datums the mechanism before moving to a requested position, datuming cannot be done until the position of the datum switches have been determined.

The mechanism can be moved under direct control using the individual mechanism DM screen, the procedure for this is:

1. Start individual mechanism DM screen using the related display button of the mechanism, eg. Image Rotator
2. Switch on the power to the motor by pushing the Power button to On
3. In the bottom half of the DM screen are the Motor Record fields, towards the bottom of this are fields used to Drive the motor, to move the motor to step S enter in the text field labelled VAL* the value S, when return is pressed the motor will start moving to step S, once there the RBV field will show step S as the current read back value, ie. the current step

Once positioned as close to the hard stop as possible recalibrate the mechanism so the current position is step 0:

1. Under the Calibration heading of the Motor Record section of the mechanism's DM screen is the field SET, enter 1 and press return, the field will now display the value SET, altering the VAL field will no longer cause the motor to move
2. Define the current step as 0 by entering O in the VAL* and DVAL* fields
3. Take the motor record out of calibaration mode by entering the value 0 in the SET field, Use will now be displayed and any changes to the VAL* field will cause the motor to move

1. Under direct control move the mechanism forward 50 steps
2. Continue moving forward 50 steps until the text update field of datum1 displays open
3. Move back 50 steps and ensure datum1 now displays closed, if this is not the case continue moving back 10 steps at a time until the switch does close
4. Move forward with 10 step increaments until the switch again goes open
5. Move back 20 steps and ensure the switch is closed, if it is not closed move back at 5 step intervals until it is closed
6. Move forward with 1 step increaments until datum1 displays open. The transition of the datum switch from closed to open with 1 step movement has now been found, record the step value displayed in the RBV field
7. Move back to the step close to the hard stop where the search for the datum switch began (step 0) and repeat steps 1 to 6 another nine times
8. The step postion of datum switch 1 is the average of the 10 step positions at which the switch was found.

Note in the above process the term moving forward implies moving positive steps from current position, ie. towards hard stop at high end of travel, and moving back implies moving negative steps from current position, ie. towards hard stop at low end of travel.

In the mechanism's pvLoad .data file update the value used as step position of datum switch 1, the record containing the value is called datum1PosLo, the line in the data file will be similar to:
long uist:ccs:imRot:datum1PosLo = 227;
Follow instructions in data/README file (see link to this file in section UIST CCS in CVS) for implementing the change.

Once the position of datum switch 1 has been determined the position of datum switch 2 can be found following the same instructions as used to find datum switch 2 of a circular mechanism, see above. While the insturment is warm only a rough estimate of datum 2 position will be posible, the procedure should be repated once the insturment is at operating temperature.

The measuring of steps between lower hard stop and datum switch 1 can not be done to great accuracy due to not being able to carry out the calibration procedure at operating temperature, however what is necessary is that during normal working operations, ie. moving to requested position and datuming, the mechanism does not hit the hard stops, carrying out the above procedure does enable this to be done. For operating accuracy it is then important to define the number of steps between datum switches at operating temperature, which can be done following the instructions above detailing calibration of datum switch 2 for Circurlar Mechanisms.