Is it possible to collect data from two separate NI cDAQ modules while set in "continuous sampling" mode?

[CowdogHank87]

I'm using a cDAQ with a NI 9237 and a NI 9205 and LabVIEW 8.6.1. Both modules arecoded using the DAQ Assistant in LabVIEW.

I would like to simultaneously read strain gage data (NI 9237) and LVDT data (NI 9205) in order to operate a piece of lab equipment at various loading profiles. However, when I try to run the VI with both DAQ Assistants set to continous sampling, I get an error saying that the "necessary resources are not available." 

To work around this, I tried to have both tasks alternate between taking a set of samples. This method is insufficient in that it produced choppy data that can't be relied on to control a machine.

Sorry if the terms I used aren't right. I'm somewhat new to labVIEW.

Thanks

[Christian Mergl · Accepted solution]

I assume you are using cDAQ-9172 chassis.

This just has one analog input timing engine, which means that only one AI Task can run at a time.

[ManLongAtNI]

An alternative to the 9172 and its single AI timing engine is the second generation cDAQ chassis(9174, 9178). This houses 3 AI timing engines allowing you to have up to 3 different sampling rates for across AI modules.

[CowdogHank87]

Thank you for your answers. You are correct about the model cDAQ I am using. I was unaware that it only had a single AI timing clock. Thank you for the information and suggestions.

[Seth_B.]

The other option is to put all your channels in one task (by putting them in one DAQ Assistant) and sampling them all at the same rate.  This way you don't have to switch back and forth.

Regards,

Message Edited by Seth B. on 12-09-2009 09:58 AM