Second DAQ assistant in power supply control system not working

[jamestang]

Hello all,

I need your help on this issue. I am currently programming a VI for a power supply control for pool boiling experiments. The flowchart of the VI program is attached.

I utilize two DAQ assistants for acquiring steady state and unsteady state temperature data respectively. The first DAQ assistant (Samples to Read 5, Rate 5 Hz) for unsteady state data acquiring works well (please see attached image file First DAQ Assistant for Unsteady State Temperature Acquiring ). The second DAQ assistant (Samples to Read 12k, Rate 200) for steady state data acquiring does not work (please see attached image Second DAQ Assistant for Steady State Temperature Acquiring), only showing series of data files in size of 1KB without any data inside. And the indicators for steady state data also showed nothing.

After searching similar Q&A in the forum, I tried to distribute different channels for DAQ assistant 1 and 2. However, the situation was almost the same.

The hardware I utilized are SCXI 1000 chassis and SCXI 1303 board for thermal couple temperature data acquiring. The power supply was AMREL SPS200-50-K025. The LabVIEW software is the 2014 version. 

I had just started to learn LabVIEW for only a month and I know the VI is a little bit messy. Hope you guys can also give me some advice on how to improve this VI. 

[jamestang]

Two detailed explanation images are attached here, so as the VI and sub VI, including the drivers for the power supply.

[Dennis_Knutson · Accepted solution]

Have you looked at the error out of the second daq assistant? You'll see a resource reserved error because you cannot use two different assistants. You don't mention the actual daq device but it has a single convert clock. You can only use a single assistant with a single sample rate.

[jamestang]

Thanks a lot, Dennis!

Yeah, previously I guessed the error might be this. Your reply helps me make sure the error type. 

It seems I need to make some big modifications. However, is it possible to use two DAQ assistants, but only one at a time? For example, before I trying to read data using DAQ assistant 2, I can close DAQ asisstant 1, making sure the device is not reserved.  

[Dennis_Knutson]

Yes, you can stop and clear a task before using another.