CIRSI Temperature Sensors

CIRSI uses a set of bimetal RS (T-Type) thermocouples to sense temperatures at various locations in the system. The temperatures can be determined manually using a hand held monitor or via sensor software than runs under WIN95 on a PC. This uses a Pico Technology TC-8 8-channel temperature logger.

Pico TC-8 8-channel 16bit Temperature sensor

Sensor arrangement during Oct/Nov INT run:

  1. top of LN can
  2. getter
  3. base plate
  4. copper heat strap
  5. chip box
  6. underside of filter wheel
  7. ambient

A brief guide to setting up the Pico Tech Logger

In order for the logger software to work, the following need to be set correctly in the Settings Menu:
  • Port eg COM1. The CIRSI computers may have two unlabelled RS-232 ports. Looking from the back of the PC towards the front: COM1 should be the left hand port.
  • Channels: These need to be set to T-type
  • Sample Rate: eg 1 per minute for 1000 minutes.

    The old version of the logger stored the data in memory and one could save the data to a file using save as in the File menu. If the PC crashed you would loose the measurements.

    The new version can write a file in real time and also plot the data in real time.

    Trouble Shooting

    Some of the common problems and solutions are described below
    1. Problem: the Temp monitor software complaining about not being able to read on com1.
      • Solution: (1) Check that the temperature unit serial cable is plugged into the COM1 on the Camera Control PC. See above about how to identify COM1 on the PC if it is not labelled (2) Restart the Temp Monitor software a few times since the link to COM1 can be intermittent at start up.

    Future Plans

    Ideally the temperature information would be stored in the FITs headers and the temperatures would be monitored over the network so that a user could be warned about any abnormalities. A short term solution would be to write the log file to a network mounted disk that was visual to the observer on a Unix system. The observing system could then read the temperature from the log file. It may also be possible to use the Pico Tech drivers to link into some of our own code.
    Richard G. McMahon <rgm@ast.cam.ac.uk>
    Last modified: Wed Nov 24 10:36:39 1999