Mixed RSE and Differential Voltages from 6220

[jed]

I am seeing a problem I have not tackled before.

I have a customer with a 6220; Originally I coded up 7 RSE voltage channels for them, ai0:ai6

I then discovered that one of their sensors needed to be differential; it happened to be connected to ai5, so I just changed the call to make that channel differential (since each channel has different limits, I already had them coded with different calls to the channel setup). So now ai5/ai13 are differential.

This worked fine.

I then added two more RSE channels on ai7 and ai8. I get:

QUOTE

Error -200019 occurred at an unidentified location

Possible reason(s):

Measurements: ADC conversion attempted before the prior conversion was complete.

Increase the period between ADC conversions. If you are using an external clock, check your signal for the presence of noise or glitches.

I should mention that this code works perfectly on a PCI-MIO-16XE-50.

Also, it will fail if I change the code so that I sample, say, ai4 in stead of ai8 (So sampling ai0-ai7 (in arbitrary order) with one DIFF is OK, sampling ai0-ai7 and duplicating one of the samples gets the error).

The error is also strange because it's a timing error (the acquisition is externally triggered, but I lowered the trigger rate to 20Hz just to make sure).

Is there anyway for me to get the 6220 working with 8 RSEs and 1 DIFF?

[Tim_S]

QUOTE (jed @ May 27 2009, 12:25 AM)

Is there anyway for me to get the 6220 working with 8 RSEs and 1 DIFF?

My inclination is to fix a hardware problem in hardware. The first thing that comes to mine is that a 5B module takes in a differential signal and outputs a NRSE signal. You'd have to reference it to be exactly like your other channels, but that shouldn't be an issue.

Tim

[jed]

Whoops. I had set the sample clock to 30K, assuming that we would have only 8 channels. Once I added a ninth sample, the total bandwidth requested climbed to 270K. The 6220 can handle 250K.

Funny thing, this came back as a run-time error only after the acquisition was started; the error came back on the read function, not the configure or the Task Start.

QUOTE (jed @ May 26 2009, 09:25 PM)

I am seeing a problem I have not tackled before.

I have a customer with a 6220; Originally I coded up 7 RSE voltage channels for them, ai0:ai6

I then discovered that one of their sensors needed to be differential; it happened to be connected to ai5, so I just changed the call to make that channel differential (since each channel has different limits, I already had them coded with different calls to the channel setup). So now ai5/ai13 are differential.

This worked fine.

I then added two more RSE channels on ai7 and ai8. I get:

I should mention that this code works

perfectly

on a PCI-MIO-16XE-50.

Also, it will fail if I change the code so that I sample, say, ai4 in stead of ai8 (So sampling ai0-ai7 (in arbitrary order) with one DIFF is OK, sampling ai0-ai7 and duplicating one of the samples gets the error).

The error is also strange because it's a timing error (the acquisition is externally triggered, but I lowered the trigger rate to 20Hz just to make sure).

Is there anyway for me to get the 6220 working with 8 RSEs and 1 DIFF?