Thermocouple Measurements using an RTD for CJC

[Jameseggleton]

I am using an SCXI 1001 chassis with SCXI 1102 cards attached to TBX 1303 units and also SCXI 1121 cards attached to TBX 1328 units. I need to measure a number of K and T typre thermocouples in this system (using 1102 cards), and was hoping to use a PT100 RTD for my Cold Junction Compensation. Is it possible to achieve this by using the excitation current from an 1121 card and measuring the RTD value with the 1102 cards. It seems that when trying to select the CJC source in Max in the 1102 setup screen, there is no capacity for reading values from cards other than 1102 cards i.e I can't read the 1121 values.

What is the best way to achieve this using the setup I have?

[Joe_W]

James,

On the virtual channels of SCXI 1102 MAX configuration if you have not set-up any additional channels at this point then the CJC selection will only offer the internal Thermistor for it's CJC reference or a user value defined one. If you wish to use a PT100 you will need to set this up in MAX first using the Virtual Channels. Once you have that working go back to the SCXI 1102 and configure the CJC reference as User Defined, you should then be able to use the PT100 channel that you have just created.

Side note: The 1102 has been designed to thermocouple measurements and the internal CJC should be accurate enough for general measurements.

Kind regards

Joe

NI-UK