multi channel data acquisition

[dingbat46]

Hi,

I have got a multi-channel data acquisition working for 3 analogue input voltages but I can't figure out how I would do it with a thermocouple input aswell, please could someone help.

[Dennis_Knutson]

If you are using the DAQ Assistant, the help window on the left that appears when you first open it, explains how to have multiple measurement types. You simply click the Add Channels button after first creating the voltage task. If you are using the DAQmx functions, you would have a second DAQmx Create Channel function after the one you already have but set the second one to Analog Input>Temperature>Thermocouple. This is done with the Polymorphic VI Selector that is at the bottom of the function or right click on the function and do a Select Type.

[minhtuanbk49]

Hi everyone, please help me with DAQ. I have a 9217 DAQ and I want to measure 3 channels simutaneously (measure Temperature via RTD).I want to enable or disable any channel anytime. I tried using a tab control for case structure to select which channel is enabled. Pls view this vi attached.

(Note: This vi built by labview 8.6). But the problem that I cant measure simutaneously as desire or disable acquisition of any channel even I press Stop.

Pls help me solving this problem. I am so grateful to your help.

[Dennis_Knutson]

Nothing you have written is correct. I'm sure you are getting an error that you are ignoring. The error would be task is reserved. You simply cannot create three separate tasks for three separate channels. You must use a single task configured for multiple channels. You can either specify multiple channels in the physical channel control or have the three separate Create Channel functions wired in series and wiring the task out to the task in of the next function.

[minhtuanbk49]

Many thanks Dennis_Knutson. Absolutely that the task still reserved so I cant do as my hope. I dont know that it can not create separate tasks for separate channels. Why is that? Is there any way to do it?

Additionally, I already thought I must using multi channels and after that I will choose a control to get the signal as desire. But if I do that, still that the remaing channels continue running, right?

Forgive me if there some thing too stupid.

Thank you.

[P@Anand]

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@minhtuanbk49 wrote:

Many thanks Dennis_Knutson. Absolutely that the task still reserved so I cant do as my hope. I dont know that it can not create separate tasks for separate channels. Why is that? Is there any way to do it?

Additionally, I already thought I must using multi channels and after that I will choose a control to get the signal as desire. But if I do that, still that the remaing channels continue running, right?

Forgive me if there some thing too stupid.

Thank you.

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You cannot create seperate task for a single card because the resource you might be having in that card is only one that is your ADC and other signal conditioning unit of that card so when you reserve it at one place until you close that you will not be able to access that even from your MAX you will get an error.

I don't understand the next statement. What do you mean by choose a control to get the signal. Could you explain that?