multiple tasks in one VI

[jimmy0691]

I am a new Labview programmer trying to measure AI voltage and Thermocouple data with the same VI (Labview 7.1).  I am using two Daqmx Read Vis in the same while loop.  I get the error message (Error 50103 occured at Daqmx Read "The specified resource is reserved")

Is it possible to have multiple tasks in the same VI? 

[pcworld]

You cannot run the two AI tasks at the same time because both analog channels share resources such as the timimg signals. The easiest way for your application is to use DAQ assistant to setup all the analog channels and put them in one task. The wizard can guide you through the process.

[jimmy0691]

Can I use the Daq assistant if I am creating the VI on a computer with a 16 channel AI DAQ card and making an application out of the VI to use on a computer with a 32 channel DAQ card? 

Thanks for your time

[Dennis_Knutson]

If you have at least version 7.5 of DAQmx (8.0 is the latest version), you can add a simulated device in MAX. Even if you don't do this, the syntax for multiple channels is pretty simple. If you want consecutive channels, (i.e. 0 through 3), it would be Dev1/ai0:3. If you want non-consectutive (i.e. 0, 2, 4), then the sysntac is Dev1/ai0,Dev1ai2,Dev1/ai4.

[pcworld]

Jimmy,

I don't think it will work since the task you created through DAQ assistant is hardware specific. You can try the simultation device function of DAQmx to simulate the hardware (32 channel DAQ) and build the task on the simulated hardware. You should be able to run the code on the other computer.

[jimmy0691]

Is it possible to sample at a different rate on different channels or do all channels have to have the same sampling rate?

[Dennis_Knutson]

The have to be the same since you have a single A/D and a single convert clock.

[Laura F.]

Hello Jimmy,

You can see this example if you would like to see an example of post-parsing your data from multiple channels so that you get different scan rates.  You are still acquiring the data all at the same rate, but then parsing out what you do not need. 

Thanks,

Laura