How to connect Type K Thermocouple to PCI-6229 and Detect change in voltage

[juangilsan]

I have problems getting variable readings on the PCI-6229 DAQ. I insert type K Thermocouple into hot water, cold water I don't see any variation in voltage. Using Differential Input with the SCB68 Connector Block and cable SHC68-68-EPM as per manuals.

I try conditioning signal by amplifying the voltage but still don't detect variation on voltage levels from changing temperatures in Thermocouple. Connect to AI0-AI8. AI8 Is connected to AI GND.

Thanks,

Juan

[DavidMN]

Hi juangilsan,

When you say that you are reading off the thermocouple using a differential input, do you have the hardware set up for a differential input signal?  Please take a look at this Field Wiring Guide (specifically table 1) and verify that you are implementing the proper hardware configuration.

Regards,

David

Applications Engineer

National Instruments

[juangilsan]

Thanks for your response David. 

Yes, David, I have it set up as differential input signal. Great info that you sent me, however my problems seems to be that I am not properly conditioning the microvolt output of the K Type Thermocouple to be read by the PCI-6229. Is there is an onboard Circuit to amplify this microvolt signal from the thermocouple.

If yes, how can I utilize it?

If not, will you be able to reccomend something that will suit my existing hardware? PCI-6229, SCB68 Connector Block.

[DavidMN]

Hi juangilsan,

The built in temperature sensor for CJC inherent to the SCB 68 should handle this.  When you create the thermocouple task, specify that the CJC source as "built in."  Also, please refer to the "Using Thermocouples" section, specifically switch settings and temperature sensor configuration, of the SCB 68 user manual for further considerations.

Regards,

David

Applications Engineer

National Instruments

[cshoyo]

Dear David

I have tried to apply what you explain in your message with a K thermocouple, a PCI 6229 card and a SCB-68 connector block. I have configured PCI 6229 properties for accesory SCB-68 - Temperature Reference Enabled. However, when I configure a 'TemperatureTask' in MAX it does not allow me to select the 'Built in' CJC Source. Can you help me with this problem?

Best regards

Carlos Soria

SPAIN

[dstrandb]

Hi Carlos,

Have you followed all the steps outlined in this KnowledeBase article? Please run through these steps, and see if you're still unable to select a built-in CJC source. I hope this helps!