Unable to measure thermocouple signal

[Foon]

Hello.

I am a new LabView user attempting to set up a temperature measurement application with thermocouples.

My hardware setup is as follows:
SCXI-1303 term block -> SCXI-1102 T/C amp -> SCXI-1000 chassis -> PCI-6034E NiDAQ

Everything sets up and tests OK in the Ni-DAQ measurement and automation explorer. All boards are untouched, per factory default...

Attached an ungrounded type J thermocouple to the terminal block, Channel 1 (red lead to -).

Used DAQ Solution Wizard to pull up a pre-developed continuous thermocouple measurement panel.

Analog device, SC1_MD1:SCXI-1102, channel 1 was selected and the panel was successfully launched.

Set up the panel as follows: Device 1, T/c Type J, Cold Junction chann
el 0, CJC Sensor Termistor, Channels OB0!SC1!MD1!1. I click on the arrow below the Edit menu to start the program. The latest reading remains steady at NaN.

I tried grounding the negative lead of the thermocouple wire to the term block's ground terminal with no success. The T/C circuit was confirmed to be closed. Swapped in other Type J T/C's to no avail. Tried different term. block channels to no avail, (making apropriate entries to the panel, of course.)

Help.

[Annette Perez]

Foon,

Hello. I suggest to do all the troubleshooting from MAX(Measurement and Automation Explorer) and once we see good readings there, then we can go to LabVIEW.

So, talking about the connections, I think we are just fine. In general we should connect the positive lead(white) to the positive channel and the negative lead(red) to the negative channel. You do not need to connect the negative terminal ground on the SCXI-130e because the negative connection of each channel on the terminal block is already wired to ground through a bias resistor.

Once we have the system ready, we can move to MAX. In MAX, make sure that you configure the SCXI chassis and that the 1102 (I assume this is your only module) is controlling your DAQ board.

Since this is g
oing to be a thermocouple reading, please make sure to set up a gain of 100 in the channel that will read the thermocouple value.

After this, lets create a virtual channel (Under Data Neighborhood) that will convert the voltage readings into temperature. For the CJC just specify Built In. Once we are done creating the virtual channel, lets test it!

Once we get it running in MAX, then we can move to LabVIEW!

Keep up the good work and good luck with your application!

[Foon]

Thanks for the tips. I successfully created and tested a couple of virtual channels. It sounds like I might be ready to move on to LabView.

Let me know what would be a logical next move.

Thanks,

Paul