Multi Channel Sampling

[Thunder-2010]

Hi All,

can any body help me in modifiyng the attached exampele to add 2 more analog channles and 1 digital channel to share tghe same digital start trigger?

Thanks

[JK1]

Hai,

Change the physical channel to "Dev1/ai0:1" to include one more analog channel and already the code has a PF10 trigger associated with it.Now the task automatically uses the trigge.

[Thunder-2010]

Hi,

Sorry, I did nt adress my inquiry very well.

What I am looking for is to add one digital signal for frequincy mesurment using NI 9401 and one more analog signal for temperature measurment using NI 9211. All thse to share the same start trigger.

Thnak You

[Thunder-2010]

Hi All,

Can Any Body help me in this case.

I am in urgent situation in my task and I am very beginner to LabView.

Regards,

[JK1]

Hai,

There are two questions:

1. The modules you have mentioned are c-Series modules.  So  you are using compact RIO or compact daq platform to acquire data from these modules.

2. The digital trigger you have mentioned is from external source of you would like to generate a trigger that needs to be shared between all the modules to initiate acquisition.

In any case i.e. trigger is from external source or generated from code you can always share it with other modules.

i.e.  If the trigger is external : connect the trigger to PFI and to digital line of 9401 module using which you can sync both the platforms.

If the trigger is generated from DAQ still you can share it using the same way as above.

feel free to post back.

[Thunder-2010]

Hi,

Thanks for your reply,

 Actually I am using Compact DAQ for this application with the mentioned moudules.

Th trigger sourse will be from the speed encouder so that every 1 degree data will start by this digital trigger.

My application simply is to colect pressre, temperature and shaft positione of rotating equipment. Aquisition will start by digital trigger signal by speed envoder every 1 degree.

I have attached one example before but it does not contain the other tewo more signals. I did another trial example as attached.

would you please look at it and advice possible sloutions. I need to add the digital signal to it.

Looking to hear from you soon as I am stuck.

thanks

[JK1]

Hai,

I simulated the cdaq devices in max and the 9401 lines are not appearing in the source list for triggering [are the 9401 lines appearing for you in the source of the trigger list?],  So as an alternate approach i  made a quick way of doing it.  find attached the vi and change the architecture to suit to your needs [i dint follow any architecuture i just did quickly].

Also, you would like to acquire the samples at only one trigger or monitor the trigger continuously and at each trigger you would like to acquire data.  

For the first case, some vi like wat i have attached will work.

Note: Adjust the sampling rate and the way you detect a high edge if the speed is high

but for the second case that is for each trigger [when the speed encoder moves 1 degree each time] this setup will not help.

Post if the requirement falls to second case.

Message Edited by JK1 on 03-17-2009 05:16 AM

Message Edited by JK1 on 03-17-2009 05:17 AM

[Thunder-2010]

First of all I would luke to express my appreciation for your kind help and support in this isues.

One more thing, I will need just the trigger to start the aquisition.

From the VI that you sent I can not see the trigger source. Also, I need the data aquisition to be synchronized and sharing the same refrence clock.

for the digita signals, the encoder wil generate 2 signals. One will be used for triggring the aquisituion and the other will be displayed only through NI9401.

can you help in this to have the system start aquisition through digital trigger signal and have the other three signals (digital from encoder, pressure and temperature being displayed in graph.

Regards,

[JK1]

Hai,

1. Trigger source: The trigger from the encoder can be connected to one of the 9401 lines (configuring the line as Input) and monitor that particular line for high or low depending on the nature of the trigger you would receive.  So taking the above option into consideration i have kept a simple while loop that monitors for a high-level trigger input from encoder and once triggered the loop stops-acquisition starts.

2. Syncronisation: In the vi ai/sampleclock is used as shared clock for all the acquisitions.  I hope it should give the required synchronisaition between tasks just give a try.

3. Create one more task to acquire the encoder signal from one other line of the 9401

Hope this helps

[Thunder-2010]

Soory for bothering you,

I have done the task of adding more encoder signal. would you please check it for me?

Final things I would like to add is|:

Writing the readings to measurment file like spreadsheet or TDMS file.

Posibility of replacing the loop by normal trigger.

Thanks