cDAQ-9263 modules won't allow independent waveform generation

[WM_John_Weeks]

I have a customer with a cDAQ-9178 crate with two 9263 modules. When he tries to start two independent waveform generation tasks on the two modules, he gets an error from DAQmxWriteAnalogF64:

device cDAQ1Mod2:-50103: NI Platform Services:  The specified resource is reserved. The operation could not be completed as specified.

Extended info:

NI Platform Services:  The specified resource is reserved. The operation could not be completed as specified.

Task Name: cDAQ1Mod2AO

Status Code: -50103

It seems like it must be a driver bug- usually these "resource reserved" errors happen when you try to commit the task, but this is coming from DAQmxWriteAnalogF64. He verifies that he can start two independent waveform generation tasks on two completely independent devices, but he cannot do it on two modules within his crate.

Is this some sort of gotcha with the modules in a crate? or a driver bug? He tells me that he has updated the driver to the "latest from the NI website" with no luck.

Thanks in advance!

[bstreiff · Accepted solution]

The cDAQ-9178 only has a single analog output timing engine; you can only have one timed analog output task generating waveforms at a time. Sadly, the 'specified resource is reserved' errors aren't more descriptive.

The DAQmxWriteAnalogF64 call pushes the task to the 'reserve' state, which is where it tries to reserve the timing engine (as well as other resources): the first task will succeed, but subsequent AO tasks will not as long as the first has the resources reserved.

Are the two tasks intended to run together at the same rate? You can put channels from both modules into the same task by using a physicalChannel string like cDAQ1Mod1/ao0:3,cDAQ1Mod2/ao0:3 with DAQmxCreateAOVoltageChan.

[WM_John_Weeks]

Thanks, bstreiff. I was afraid it was something like that.