Introduction

LRIS has four temperature sensors associated with the detector system, covering the CCD and saddlebag temperatures for the red and blue sides of the instrument. The following table details these values:

System temp	Library	Keyword	Nominal	Acceptable Range
Blue CCD	lrisblue	tempdet	-120.0�C	-121�C to -119�C
Red CCD	lris	tempdet	-140.0�C	-141.0�C to -139.0�C
Blue saddlebag	lrisblue	utbtemp	-5�C	-10.0�C to 6.0�C
Red saddlebag	lris	utbtemp	1�C	-10.0�C to 6.0�C
Notes: Saddlebag temperatures come from sensors on the Leach utility board. The red and blue saddlebag temperatures differ significantly because the blue utility board temperature was never properly zeropointed.

Checking Temperatures

Temperatures are checked in three different ways

1. Via script. Issue the temps command on lrisserver to get a printout of the current temperatures:
   manuka{lris}130: temps

   System               Current Temp  Acceptable Range  Status
   -------------------  ------------  ----------------  ------
   Blue CCD temp              -120.9  -121.0 to -119.0  OK
   Red CCD temp               -139.9  -141.0 to -139.0  OK
   Blue saddlebag temp           1.5   -10.0 to    6.0  OK
   Red saddlebag temp            3.5   -10.0 to    6.0  OK
   

2. Via keyword. Use the show command to check the temperatures. The commands are as follows:
   

   System temperature	Command
   Blue CCD	show -s lrisblue tempdet
   Red CCD	show -s lris tempdet
   Blue saddlebag	show -s lrisblue utbtemp
   Red saddlebag	temp show -s lris utbtemp

3. Via cron job.LRIS temperatures are checked every 10 minutes using the monitor_tempdet2 program executed by the cron job run_monitors on lrisserver. Temperature errors will generate emailed messages. See the info on temperature alarms below.

Troubleshooting invalid temps

1. When power to the saddlebags is down or the electronics is reading out or communication with the saddlebag is down, the system reports invalid temperatures for the detector and utility board.
   • The red CCD temperature will be 52.98�C, and the utility board will report -1375�C.
   • The blue CCD temperature will be 49�C and the utility board will report -1375.5�C
2. CCD undertemp: if the CCD temperature is too cold for a long time, the CCD heater inside the dewar may have failed or been disabled.
3. CCD overtemp: if the CCD temperature is too warm for a long time, the liquid nitrogen coolant may have evaporated.
4. Saddlebag overtemp: if the saddlebag is too warm, the instrument glycol system may be running too warm.

Temperature alarms

The state of LRIS CCDs temperatures is constantly monitored by means of a cron job which starts the script monitor_tempdet2 for the red and the blue side every 10 minutes. The script checks the CCD temperature for the specified side of LRIS and send out email alarms under one of the following conditions:

• The temperature is higher than the legal maximum
• No valid temperature has been read for 35 minutes or more

During a programmed warm up or while troubleshooting the crates, there are two proper ways to disable them temporarily:

1. Issue the following command on lrisserver as lriseng:
   monitor_tempdet2 red disable (or) monitor_tempdet2 blue disable
2. Logon as any lris account on lrisserver. From the LRIS Control Menu (right click on the blue background) select Engineering, Alarms... and select one of the possible entries:
   
   1. Temporarily disable (snooze) red CCD temps checks
   2. Temporarily disable (snooze) blue CCD temps checks
   3. Indefinitely disable red CCD temps checks
   4. Indefinitely disable blue CCD temps checks
   5. Enable red CCD temps checks
   6. Enable blue CCD temps checks

This will temporarily turn off temperature monitoring, but will cause a reminder message to be sent out once per day to lris@keck.hawaii.edu reminding folks that the monitors are disabled and giving instructions on how to re-enable. This latter can be done by issuing the following command on lrisserver as lriseng:
monitor_tempdet2 red enable (or) monitor_tempdet2 blue enable