Background

DEIMOS gratings are retained in place using four pneumatically-operated clamps, numbered 1, 2, 4, and 5. Each of these devices has an air cylinder which fires to close the clamp and another which fires to open the clamp. The clamps are typically not controlled individually by the user; instead, a firing sequence which is optimized to produce reliable grating clampup is defined in the Galil motor controller code used to operate the clamps. However, under certain conditions it may be advantageous to be able to operate the clamps individually. This document describes the procedure for operating clamps individually.

Caveats

These steps carry risk of overheating and destroying solenoids if not followed carefully.
These steps also carry risk of damaging either the grating clamps or the slider assembly, if the clamps are fired in the wrong order or in the wrong position. Make sure that the slider is fully clamped using the automatic procedure before stopping the dispatcher.
These steps should only be performed by a WMKO Instrument Technician/Engineer or Support Astronomer.

Notes

Each grating clamp is opened by generating a pulse on a given output port bit and closed by generating a pulse on a different output port bit. You can generate a pulse on bit 'n' by issuing the commands CBn or SBn in rapid succession. WARNING: You must avoid issuing a pulse that is more than a few seconds long or you can overheat the pulsed solenoids that operate the grating clamps.

Procedure

Stop the dispatcher process that controls the grating-related components. This is the dispatcher2.2 process that runs on host keamano:

	[64] dmoseng@keamano: deimos status dispatcher2.2
	dispatcher2 -s deimot -n 2 is running on this host; pid = 19766
	It can be stopped by this script if you have privs.
	dispatcher logfile is /local/kroot/var/log/dispatcher_logs/deimot_dispatch_2_log.2011-10-31

This process runs under the kics account. It can be stopped by issuing the following command when logged into keamano as kics:

	deimos stop dispatcher2.2

Establish a telnet connection to the Galil controller that is normally controlled by the dispatcher2.2 process. This will allow you to issue low-level commands directly to the hardware. As such, from this point on, you need to proceed very carefully, because there is the potential to do real damage if the clamps are fired when the grating is not adequately aligned with the grating box. To establish the telnet connect, from host keamano, use the command:
```
telnet 192.168.6.4 3006
```
Press the Enter key to verify communciations with the Galil controller. It should respond with a colon (:) prompt.
Stop any running threads by issuing the ST command.
Determine via the table below which bit must be toggled in order to close or open the desired clamp.

Move the clamp by issuing the appropriate command on the Galil:

Clamp	Open	Close
1	CB 26;WT 100;SB 26	CB 25;WT 100;SB 25
2	CB 28;WT 100;SB 28	CB 27;WT 100;SB 27
4	CB 32;WT 100;SB 32	CB 31;WT 100;SB 31
5	CB 34;WT 100;SB 34	CB 33;WT 100;SB 33

Note that the relevant commands are:

CB: clear specified bit
WT: wait for specified number of millisec
SB: set specified bit

Reset the Galil controller by issuing the command:
```
RS
```
and wait for the controller to respond with
```
:  arriba!
```
Close the telnet connection by entering Ctrl+]
Restart the motor control dispatcher by entering this command as user kics on keamano:
```
deimos start dispatcher2.2
```
then verify that the process is running via
```
deimos status dispatcher2.2
```
The paranoid will then run testAll to ensure that all is well.

Background

Caveats

Notes

Procedure

See Also