Agilent 34972a basic temp function with drivers

[ccoker765]

Hello,

I've been able to get reliable data from a Keysight DAQ970A using the Agilent 34970a EZ Temperature driver and the EZ Voltage driver separately.

I tried using the EZ Temperature driver together with the EZ Voltage driver, and the EZ Temperature doesn't play well with the EZ Voltage driver, so I've been advised to break down the programming to integrate both functions (recording thermocouple and voltage data reliably together.)

I've been working to create programming just to take basic thermocouple readings to start off with and have failed in doing so.  It seems fairly straightforward and I followed the basic principles (1. Configure all channel mode, ranges, etc; 2. Configured the scan; and 3. Triggered the scan) but I'm still getting false readings of temperature (I have a tc in the correct channel, so I should be reading around 25 degrees C).  I've provided screenshots of the basic programming, am I doing something wrong or does is this programming just not supported by Keysight?

Thanks in advance!

[RTSLVU]

The picture looks correct (BTW please post your VI not a picture of your code) 

1. Are you setting the right thermocouple type?
   1. Different types have different mV/Degree output
2. Do you have the thermocouple connected correctly? 
   1. Thermocouples have a + and - that corresponds to H and L on the DAQM901A card

[antoniobeta]

Hi!

Look at the official example, maybe you are reading before the instrument measurement operation is completed and that’s why you are getting odd values.

Try configuring the trigger and using the operation complete bit setting to be sure the measurement is ready to be read.

[Minions]

Let me guess what you are doing.

You are holding the thermocouple in your hand and expecting it to read around 37C, but instead it is reading 57C.

The issue here is that your reading has not subtracted the CJC temperature for the room temperature which is probably near 20C.  It appears that without a valid CJC, it is assuming a value of 0C which explains the 57C reading.

Inside most cards in slot 100 within the 34970A where temperature measurements are made there is usually a CJC.  Read the manual about the thermocouple reference junction.  You may need to add these.

[ccoker765]

Thanks for the help!  I discovered that my technician mis-wired the cards 🙃