Channel numbers and the USB-6259 BNC

[WM_John_Weeks]

The front panel of the USB-6259 BNC device labels the BNC connectors as channels 0-7 and 16-23. Most odd... I have software written in C++ using NI-DAQmx that my customer is trying to use with this device. When using the higher channel numbers he (not unnaturally, really) gets error -200077 saying that they can only be used in single-ended mode. But it is also not unnatural for him to use the channel numbers printed on the face of the device.

Can anyone tell me how the front panel of this device relates to the channel numbers you have to specify in code?

Is this changed by the FS/GS (Floating source/Grounded source) switch that appears under each BNC connector?

Here's my guess: Differential mode: in software, channels 0-7 are front panel channels 0-7. Software channels 8-15 are front panel channels 16-23.

Single-ended mode: software channels 0-7 are front panel channels 0-7, and software channels 16-23 are front panel channels 16-23. And channels 8-15 and 24-31 are missing in action...

[Dennis_Knutson · Accepted solution]

It should be just the opposote of what you have. When in differential mode, aix is paired with aix+8. so, channels ai8, ai9, ai10, ai11, ai12, ai13, ai14, ai15, ai24 ,ai25, ai26, ai27, ai28,ai29.ai30, and ai31 are unavailable for selection in differential mode. The front panel labels for ai15-23 should be correct and match what you select in software.

[WM_John_Weeks]

Yes, my mistake. I'd forgotten that the channels come in groups of eight when you have 32 channels. And in looking back at my customer's question, he was asking about the message that says:

You Have Requested: DAQmx_Val_Diff
You Can Select: DAQmx_Val_RSE, DAQmx_Val_NRSE

when he tried to use channel 8. I actually knew this...

Thank you, Dennis!