How to read multiple voltages from DAQ at same time?

[shahidi124]

  Hello all,

  I am attempting to read multiple voltage inputs to my USB-6008 DAQ but when I try to read a second voltage, I get an error saying "Erorr 50103 the resource is reserved." Someone in another thread said:

"The reserved resource is your DAQ board. You should not be using two separate simultaneous tasks for the same DAQ board. You should use a single task with two channels configured."

So I made multiple channels in one task, but I don't want to read all the channels at once. Is there a way to specify which channel of the task to read? Or is it not possible to acquire multiple voltages from the DAQ at all?

So the question boils down to: if you have 3 different voltage inputs into your DAQ, all corresponding to different components, is there a way to be tracking and reading all of them at the same time?

Thanks a lot

[smercurio_fc]

Yes, you cannot have simultaneous same-type tasks (i.e., two analog input) tasks. The limitation is one of hardware, not software.

I'm a little confused over your question. You first said that you set up a task to read all 3 channels, but you want to specify which ones to read. But then you seem to be asking if there's a way to track and read 3 different voltages at the same time. So I'm not sure whether what method of read you are trying to do. Do you want to set up the task to read all channels and then pick out which ones to look at? If so, you can just index out the individual data. Are you using the DAQ Assistant? If so, then you have dynamic data and you'd need to use the Select Signals Express VI to pick out which ones you want to work with. Under what circumstances would you change which channels you want to read? Is this done prior to starting the data acquisition, or is this something you want to change "on-the-fly"? If it's the latter you would need to stop the current task and create a new one. I'd suggest a state machine template. Application Design Patterns: State Machines

You may also want to peruse these:

Complete Data Acquisition Tutorial

NI-DAQmx Express VI Tutorial (if you're using the Express VIs)

[_Bryan]

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@shahidi124 wrote:

  Hello all,

  I am attempting to read multiple voltage inputs to my USB-6008 DAQ but when I try to read a second voltage, I get an error saying "Erorr 50103 the resource is reserved." Someone in another thread said:

"The reserved resource is your DAQ board. You should not be using two separate simultaneous tasks for the same DAQ board. You should use a single task with two channels configured."

So I made multiple channels in one task, but I don't want to read all the channels at once. Is there a way to specify which channel of the task to read? Or is it not possible to acquire multiple voltages from the DAQ at all?

So the question boils down to: if you have 3 different voltage inputs into your DAQ, all corresponding to different components, is there a way to be tracking and reading all of them at the same time?

Thanks a lot

---

I don't understand your question.  You made a task to read all the channels at once, but you do not want to read all the channels at once?  And you want to track and read all the channels at the same time?

You need to explain it a little bit better and add some code of what you have done so far.  A task will read all the channels in the task and give you the results so you can track them.  So I am confused.

[shahidi124]

  I apologize for being unclear in my initial post.

  I am trying to accomplish 3 things: use a sensor to determine a frequency, the amount of load a load cell is applying, and the temperature a thermocouple is recording. These 3 things can all be determined with the voltage output of the sensor, load cell, and thermocouple respectively. I currently have 3 seperate .vi's for these measurements and they all run normally individually. During a test, however, I wish to be able to record all these values constantly, but when I try to LabView says that I cannot do so (resource reserved as stated above).

  So my question is, is it possible to run all these .vi's at the same time?

  I will try using Select Signals Express VI as  smercurio_fc suggested but I just wanted to clarify what the issue was and I hope this helped in that respect.

  Thanks

[smercurio_fc]

As already noted, you cannot run those tasks simultaneously. This means that you cannot run those subVIs at the same time. You will need to merge the data collection into a single VI that collects all 3 measurements at once and then parcels out each one.

[ssasasas]

So how do you parrcell each on out?  I'm having this issue to but all of my voltages from each channel in my DAQ assit merge into one data output.  How do I seperate these to be there own data output?

[aeastet]

Post your code so we can see what you are doing and we can help from there. It should be very easy but we need to know what you are doing in order to help.

[RavensFan]

There is a split signals function on the Express palette.