CJC for Multiple SCXI Modules

[youngds01]

I am setting up an SCXI signal conditioning system to measure 20 thermocouples using three 1320's and three 1120's in one SCXI-1000.  When using MAX (setup as one task), I have a couple of questions:

1.  Is there any special or unique ways I have to setup MAX because I have multiple modules or does setting the "CJC Source" to "Built In" work correctly?

2.  Which CJC of the three 1320's does max use for each channel?

3.  What should the 1320 jumper be set to (MTEMP or DTEMP)?  Assume I am in multiplex mode.

Thank you in advanced for your support.

Dan Young

[hoffiz]

Hi Youngds01:

I would like to point you to this KB How Can I Address and Use Cold Junction Compensation (CJC) with SCXI Modules?

1.       Is there any special or unique ways I have to setup MAX because I have multiple modules or does setting the "CJC Source" to "Built In" work correctly?

There is no correct way of setting up the CJC source it will depend on what you want to accomplish. You can use multiplex mode or direct mode by changing the jumpers (MTEMP or DTEMP), let’s say you will like to read the room temperature with scxi-1320 #1 you will set this for DTEMP and use SCxMody/_cjTemp to address the channel.

2.       Which CJC of the three 1320's does max use for each channel?

It will use all each CJC for each SCXI-1320, so for example every time there is a measurement in SCXI-1320 #1 and SCXI-1320 #2 it will read the CJC of the 1320 #1 and then the 1320 #2.

3.       What should the 1320 jumper be set to (MTEMP or DTEMP)?  Assume I am in multiplex mode.

You will set it up depending on what you would like to do. I will suggest setting the jumper to “mtemp” and if you will like to read that value from the CJC of one of the modules just use SCxMody/_cjTemp as the address where x = chassis and y = module.

I hope it helps