From LabVIEW, how do I programmatically determine 'open thermocouple' status on a TC-120?

[DavidBoyd]

Apart from getting a large value (e.g., 1770 degC) on the channel when doing a FP Read, and getting a 33443 warning:

'Bad channel status reported by several channels. At least one channel is in one of the following states: Unconfigured, Bad Status "A", Bad Status "B" : FP Read.vi'

I can't find any utility VI which would give me a definitive 'open TC' status. Since MAX can report this, I figured there had to be a corresponding way in LabVIEW.

Thanks in advance for responses!

Dave

[Aaron_G]

Dave,

The 33443 error, "Bad Channel Status", is returned when performing a multi-item read/write when one or more channels is in an error state. If you were performing a single item read/write (e.g. read Channel 0 instead of All), the FP Read will return error 33489, "Open Thermocouple Detected" or error 33487, "Out of Range" (if channels in voltage mode).

Regards,
Aaron

[DavidBoyd]

Thanks, Aaron. I admit I hadn't tried a single-channel read to see if the error got more specific.

I guess I shouldn't be so nit-picky, but it might've been nice if there were a multi-channel 'read status' FP VI. Having to read individual channels (with all those associated FP tags cluttering the BD) just to get status seems a bit inelegant, and defeats the efficiency gains of doing a module-wide read.

Alternatively, this looks like one of those places where returning 'NaN', or '+Inf', '-Inf', on a floating point FPRead, would be appropriate.

I suppose I can do an array test for '>=1770', then manipulate the data to convert open channel readings to NaN. (I like NaN since multiplot charts/graphs handle it as a pen lift, and omit it from aut
oscaling.)

Thanks again!

Dave