Using DAQ Channel Concurrenly

[Maris]

Hello,

I used DAQCard-6036E 16-bit Multifuction I/O to acquire analog signal voltage from DAQ channel, and then I want to display those signal  at wavegraph in Labview software.
I have made a VI software (block diagram) to acquire analog signal voltage from one  DAQ channel, and display it to the wavegraph. Now, I want to acquire concurrenly analog signal voltage from all channel DAQ (8 channels), and display each signals at different  wavegraph, so I can see 8 analog signal voltage at 8 wavegraph. Is it possible ? If it possible, Could you please give me example program at VI Labview Block Diagram just for 2 channel input?

Thank you very much for your help.

Best Regard


Cornelius Bambang

[Dennis_Knutson]

You just have to specify multiple channels in the physical channel control (or in the task you created in MAX). The syntax for continuous channels is 'Dev1/ai0:7' for channels 0 through 7 for example, and 'Dev1/ai0,Dev1/ai2' for channels 0 and 2 for example.

You can use the Index Array function or the Split Signal function to separate the data from the DAQmx Read into individual channels.

[Maris]

Dear Dennis,

Thank you very much for your response.

I have yet clear to understand your answer. Where can I write that syntax ?

I attach this email with my vi project and also MAX configuration for that vi project.

Would you help solve my problem ?

Thank you for your time

Regars

C. Bambang

[Maris]

Dear Dennis,

Thank you very much for your response.

I have yet clear to understand your answer. Where can I write that syntax ?

I attach this email with my vi project and also MAX configuration for that vi project.

Would you help solve my problem ?

Thank you for your time

Regars

C. Bambang

 

[Dennis_Knutson]

When I said the physical channel control, I mean exactly that. You have a front panel control called Physical Channel. Either type in the list or click the little arrow on the right side of the control. Instead of just picking one channel, use the browse option and either shift-click or ctrl-click to select multiple channels.

You will have to remove the duplicate code in your program. You can only have a single task running for a specific resource.

You attached an image of some tasks that you created in MAX but you are not using the tasks in your VI. When you create a task, you have the option of selecting multiple channels. Plainly visible is the 'Add Channel' option on the top of the task window. You could use that as well.

[mallorim]

Hi Cornelius,

To expand upon what Dennis said, you do not need to make any changes to the block diagram for acquire over multiple channels. This is manually done on the front panel by typing in the physical channel control box. This can be seen in the attached screenshot.

                 

Adding channels will add multicolor plots to the same waveform indicator. If you want to have 8 different graphs, as Dennis stated, this can be done by using the Index Array Function. This function takes the data from the DAQmx read and returns the specific elements of the array that you input. In order to index multiple elements, after placing the function on the block diagram, you can click on the bottom and drag down to expand the number of inputs. This can be seen in the attached block diagram screenshot.

If you right click on the outputs of the Index Array Function and create Indicators, on the front panel a text box with appear with amplitude and timestamp data. You will want to right click on this Indicator and select Replace>> Graph>> Waveform Graph in order to get the graph indicators you desire.

I hope this explanation helps. Good luck, Mallori M.

Message Edited by mallorim on 12-14-2007 11:34 AM

Message Edited by mallorim on 12-14-2007 11:38 AM

Message Edited by mallorim on 12-14-2007 11:38 AM

[Maris]

Hi Dennis & Mallori,

Thank you for your explained about my problem, I have little modified my VI, and now I can see 2 signal from two channel at the two display.
But the physical Channel button at Front Panel doesn't serve function to choose where physical channel (ai1 or ai2) that use to acquire signal, and I can't setting timing parameter from the Front panel.
Let me know detail :
The wavegraph will show the signal according to setting parameters (physical Channel, minimum/maximum range amplitude, Sample per channel and sample rate), you can see the attachment Front Panel. So if I set channel parameter 1 and timing parameter1 for channel ai1(Dev1/ai1), the wavegraph will show signal from channel ai1, and also for channel parameter 2 and timing parameter 2. The phisical Channel button can acquire only one signal from ai0 until ai7 (according to the channel that chosen). If I have 8 wavegraph so I also have 8 setting parameter.
Would you please help me to do the Vi program for my system ? I attach screenshoot for my MAX configuration, Front Panel, & VI program.

Thank you for your cooperation

Regard

Cornelius

[Dennis_Knutson]

Delete all of the duplicate code you have. You cannot have a second DAQms Timing function. All channels have to use the same timing. And you would only use a second DAQmx Create Channel if you wanted different limits or a different configuration for a different channel. And, in that case, you would need to use the DAQmx Create Channel for the same task as the other DAQmx Create Channel. I'm also not sure why you provide the name of an existing task and then use the DAQmx Create Channel. If you have an existing task, then you don't use the DAQmx Create Channel unless you want to add a new channel to the task.

You might want to spend some time reviewing the information at http://zone.ni.com/devzone/cda/tut/p/id/5434

Message Edited by Dennis Knutson on 12-17-2007 08:50 PM

[Maris]

Hi Dennis,

Thank you for your explanation, I have modified my VI but I am confuse, where I can connect the second DAQmx Create Channel ?

Thank you very much.

Best Regards

Cornelius

[Maris]

Hi Dennis & Mallori,

Thank you very much for your help and your explanation about my VI problem. Today, I find solutin about my problem.
But if I find a problem at my VI at the next time, I hope you would help me again.

Thank you very much

Best regards

Cornelius