Agilent 34980A Thermocouple read error

[crossrulz]

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@Option13 wrote:

Oops, guess I uploaded the wrong version! I've been trying to hook it up to both RTDs and thermocouples and have configured the VI with both Thermocouple and RTD Vis. No change. The other VIs are just there for experimentation and to play with, if they present an issue I can remove them.

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You are getting an initialization error.  Are you sure your VISA session is correct?

[Option13]

I'll go back and check it, but it should be correct. I'm not currently hooked up to the device and ran the VI just to make sure the settings were correct and transferred to the TC sub VI. That's probably the source of that error. The Agilent takes data most of the day, so I can only connect at certain times because the Agilent can only support one session at a time. Makes this job a bit more difficult...

[RTSLVU]

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@Option13 wrote:

Hello all,

I am attempting to get readings off of a thermocouple using an Agilent 34980A unit connected to my laptop via ethernet cable. The VI is based off of an Agilent provided example. It is connected to a T-type thermocouple plugged into channel 9, card 1. I have been able to get numbers and no error codes, however, the output values are basically either infinity or zero. 

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That is often indicative of an open/bad thermocouple.

Does the thermocouple read properly if you program the instrument manually and read the display?

[Option13]

On an alternate, bespoke DAS the thermocouple reads just fine. After hooking up to the Agilent I changed the channel to see if that was the issue. Attached are the results screens. The error codes are why I changed to an RTD sensor, to see if those would read.

"1001" should be on card 1 (Agilent 34925A), channel 1, labeled "XS28" on our unit although I do not know if that is just on this unit. 

[crossrulz]

Let's try to reduce where the error is comming from.  Do a scan of just the thermocoupler.  Do not configure or scan the RTDs.

[Option13]

Okay, I took it down to just the one thermocouple scan. The front panel shows 2.9118 E+01 (29.811 degrees Fahrenheit) and the same error codes.  

[Option13]

I changed the reference junction. While I no longer get the error code, the output is still not correct. Setting to a fixed reference junction outputs +2.19272000E+01, and setting to external results in an output of -9.90000000E+37.

Again, the unit is collecting good data. How can I get LabVIEW to interpret it properly?

[Dennis_Knutson]

Why do you say the unit is collecting good data? I know for a fact that the result displayed on the front panel was exactly what the program displayed.

[Option13]

Because the Agilent is hooked up to a different data acquisition system when I am not trying to make it work with LabVIEW. I have not compared the LabVIEW readings it to the instrument front panel readings.

[Dennis_Knutson]

Please make that comparison. You can manually configure the instrument, do a single scan, then programmatically fetch that reading.