02-04-2017 10:32 AM
I'm running into an issue where the AISupportedMeasurementTypes function (of NationalInstruments.DaqMX.Device) is returning way more options than seem reasonable. For example, when I request this from a NI 9239 module, I get 10 options, including Thermocouple, VoltageCustomwithExcitation, and Current. I do not believe that any of these options are valid. I see this with some other modules as well, including NI 9218. I am currently using the library with a version of 15.5.45.109, which I believe is the latest (or it was a month or two ago).
Has anyone else seen this behavior, and if so, is there a "workaround"? I want to limit the user's choices to only valid selections, but this seems to be a major issue! Any ideas would be very welcome!
02-06-2017 05:43 PM
The NI 9239 is capable of acquiring those signal types as well as the NI 9218.
Are you wanting to limit the selection beyond what the device is capable of?
02-11-2017 02:54 PM
Ok, well this board does not provide an excitation signal, and only reads in a +/- 10V signal. I'm not sure how that's compatible with the signal types I mentioned without additional hardware. It seems I am missing something here.
02-13-2017 05:01 PM
Using thermocouples and measuring current don’t require External Excitation.
02-13-2017 06:38 PM
Ok ... I've never seen a thermocouple attached to a high-level voltage AI, and why would you try to read a current signal on a voltage board? Finally, when there's no excitation, why is the VoltageCustomwithExcitation a valid option? I guess to me these are not "normal" choices for this board ... even if it's technically possible for some of them. I'm certainly not trying to start an argument, so I'll stop here, but to me these options make no sense. Are there any other opinions on this out there?
02-14-2017 04:09 PM
I’d have to agree that these are not the normal use cases for these devices.