topic Re: Edge counting with digitial pause trigger in Counter/Timer

Edge counting with digitial pause trigger

Rajaram — Tue, 22 May 2007 10:19:12 GMT

I should write a program for edge counting with digital pause trigger in visual basic. I have found an example of using pause trigger in edge counting but it is written in C#.

Steps in the program followed is:

1) creating task

2) creating count edge channel objecy

3) configuring thr trigger ( where i have been strucked)

code in c # is:

taskname.triggers.pausetrigger.digitalleveltrigger ( source, level)

When i tried to look for trigger function and to configure it in Visual Basic, I have not found any trigger function to set/configure in the function library

Thanks

Re: Edge counting with digitial pause trigger

AdamB — Wed, 23 May 2007 11:32:34 GMT

Hey there,

I'm looking into this for you, but before I go into too much detail with it. What versions are you using?

What Hardware are you using?

What version of VB are you using?

What version of DAQmx are you using?

and

What device are you trying to set the Pause trigger up on?

I think the properties you are looking to set are in the "DAQmx.DAQmxSetDigLvlPause~" options.

But with more info I can't be sure. Have a look at those properties.

Thanx

AdamB

Re: Edge counting with digitial pause trigger

Rajaram — Wed, 23 May 2007 12:36:51 GMT

Hi Adam,

Thanks for your response.

DAQmx version: 8.3

VB version: VB 6.0

Hardware: PCI 6602

I am trying to use one of the counters to act as trigger (say counter 0) , which I would like to use it as a trigger (Gate) for other 7 counters. In one of my other post I got a reply that I can use PFI to set up trigger instead of RTSI signal, I am new to all these things, it will be great if i am getting some explanation of using trigger in counters. In that C# example, I tried to use the trigger source, with and without connecting to source supply, but still I am getting counts when the gate level is High, So could you suggest me about setting up the source as well. If any explanations needed, I am happy to state my problems clearly. This project I am converting from Traditional DAQ to DAQmx, I have attched my VB program and also the example C# program which I got from NI website for pause trigger.

Thanks

Message Edited by Support on 07-16-2007 10:52 AM

Re: Edge counting with digitial pause trigger

AdamB — Thu, 24 May 2007 08:18:08 GMT

Hi,

Have you had a look at the function I showed you?

These are the three setting you need to set in VB for the pause trigger:

DAQmxErrChk DAQmx.DAQmxSetPauseTrigType(taskHandle As Long,data As DAQmxTriggerType4)
DAQmxErrChk DAQmx.DAQmxSetDigLvlPauseTrigSrc(taskHandle As Long,data As String)
DAQmxErrChk DAQmx.DAQmxSetDigLvlPauseTrigWhen(taskHandle As Long,DAQmx_Val_Level1_High/Low)

The "taskHandle" is the Handle for the counters task.

DAQmxTriggerType is deciding whether you need digital trigger,analog etc.

In the "..TrigSrc..." function the "data" is the string value of the line you are using as the source for the trigger

and "...TrigWhen..." sets the trigger level you want to start and stop the trigger. "DAQmx_Val_Level1_High" or "DAQmx_Val_Level1_Low"

Hope all this helps

AdamB

Re: Edge counting with digitial pause trigger

AdamB — Thu, 24 May 2007 09:04:22 GMT

Here's the code I made

AdamB

Re: Edge counting with digitial pause trigger

Ram. — Thu, 24 May 2007 09:12:07 GMT

Hi Adam,

Thanks for your response, I am not able to open the file you sent, as there is no .frm or .bas files in it. It has only one .vbp file. Could you please make sure all the files has been zipped?

Thanks

Re: Edge counting with digitial pause trigger

Rajaram — Thu, 24 May 2007 09:40:19 GMT

Hi,

Thanks for your swift response, I am not able to open the VB project as there is no form in it. And also could you give some description about how the pause trigger works on that C# example, bcoz i tried using source connected to the pause trigger, but it gives same result irrespective of connection of source.

Regards

Re: Edge counting with digitial pause trigger

AdamB — Thu, 24 May 2007 09:52:43 GMT

Hi there,

Here is the code in text format. That's pretty much all you need. I took the example code called CntDigEvents.vbp and added the following code before the start task function call:

    DAQmxErrChk DAQmx.DAQmxSetPauseTrigType(taskHandle, DAQmx_Val_TriggerType6_DigLvl)
    DAQmxErrChk DAQmx.DAQmxSetDigLvlPauseTrigSrc(taskHandle, "PFI0")
    DAQmxErrChk DAQmx.DAQmxSetDigLvlPauseTrigWhen(taskHandle, DAQmx_Val_Level1_High)

As for the C# code I am not familiar with C# so I don't think I can be a great help on that one.

myTask.Triggers.PauseTrigger.ConfigureDigitalLevelTrigger(triggerSourceTextBox.Text, gateLevel) This function is the main call for the pause trigger and all it is doing is setting the properties. triggersource should be along the lines of "PFI0" or "Ctr0" and gate level defines whether the gate level is "high" or "low)

How is the VB code going?

AdamB

Re: Edge counting with digitial pause trigger

Rajaram — Thu, 24 May 2007 10:04:15 GMT

Hi Adam,

This has been a great help to me, I am writing an application in VB, so this is fine. I am writing a project with edge counting and using the pause trigger functions you have noted me. So hopefully there should be some process in my project. As you might have seen my traditional DAQ program which I have attached before, I just want to write the same functionality as our hardware, requirements and programming language has not changed except the driver ( DAQmx). Hope this could be a good start for to make the trigger work with edge counting function. I have written another project in VB for Pulse train generation, So the idea is giving the output of the pulse train as the terminal for pause trigger and giving the trigger output ( gate output) to other 7 counters. Does is make sense ? or is there any other way around to solve this issue?

Thanks

Re: Edge counting with digitial pause trigger

Rajaram — Thu, 24 May 2007 14:36:18 GMT

Hi Adam,

I have written the program and it seems to be fine. but when i am stopping the task, I have two functions in it

If taskIsRunning = True Then
      1) DAQmxErrChk DAQmxStopTask(taskHandle)
       2) DAQmxErrChk DAQmxClearTask(taskHandle)
    End If

I am getting an error " Error: - 200088 Task specified is invalid or does not exist. There is some error been generated when accessing cleartask.

Thanks

Re: Edge counting with digitial pause trigger

AdamB — Thu, 24 May 2007 14:46:20 GMT

Hey there,

Now you shouldn't normally get any kind of error using this, however the Clear task does actually stop the task first. And THEN clear the task.

I would suggest taking out the stop task.

AdamB

Re: Edge counting with digitial pause trigger

Rajaram — Thu, 24 May 2007 15:07:38 GMT

Hi Adam,

I have tried to run the program without stop task and just having clear task, but still i m gettin same error as @ task not specified @

Thanks

Re: Edge counting with digitial pause trigger

AdamB — Thu, 24 May 2007 15:12:37 GMT

Sounds like you have already cleared the task previous to this part of the code.

Have you traced through to see if this is repeated more than once?

AdamB

Re: Edge counting with digitial pause trigger

Rajaram — Thu, 24 May 2007 15:19:37 GMT

Hi,

Yes I have checked it. there is no repetition. I have attched my program for your reference.

Thanks

Message Edited by Support on 07-16-2007 10:53 AM

Re: Edge counting with digitial pause trigger

Rajaram — Fri, 25 May 2007 10:36:34 GMT

Hi Adam,

I have written a VB program in generating a continuous/finite pulse in counter 0 and having the output of counter 0 as trigger source and it works fine. Thanks for your help. Now I am working to implement the program functionality based on our application. I do have some questions

1) When I select clear task , still I get the same error.

2) If I am using the program and if i tried to run it again, I get an message as source/terminal reserved. So I reset the device in MAX and it is fine. Is it possible for me to reset the device in the VB program itself? So that if I am closing my program the device should clear the reserved terminals.

Thanks

Re: Edge counting with digitial pause trigger

Rajaram — Fri, 25 May 2007 11:24:10 GMT

Hi ,

I got another problem with generation of pulse. When I have continuous samples used in the function below:

DAQmxErrChk DAQmxCfgImplicitTiming(taskHandlepulse, DAQmx_Val_AcquisitionType_ContSamps, numSampsPerChannel)

it is working fine, it generates the pulse. But when I try Finite samples it is not working properly. There is no pulse being generated.

Have attached the program for reference.

Thanks

Message Edited by Support on 07-16-2007 10:53 AM

Re: Edge counting with digitial pause trigger

AdamB — Fri, 25 May 2007 11:36:31 GMT

Hi there,

What you need is to change the stop button code to this.

Private Sub cmdstop_Click()
If taskIsRunning = True Then
        DAQmxErrChk DAQmxStopTask(taskHandle)
        DAQmxErrChk DAQmxClearTask(taskHandle)
        taskIsRunning = False
    End If
    cmdstart.Enabled = True
End Sub

You need to set the task is running to false at this stage to stop the code from trying to sample the counter again.

That should solve the problem

Thanx

AdamB

Re: Edge counting with digitial pause trigger

Rajaram — Fri, 25 May 2007 11:47:22 GMT

Hello.

Thanks a lot. That fix the problem, Still I have some problems in the program

1) I need to reset the device everytime in MAX explorer to clear the reserved space, is there anyway to reset the device when I close the application?

2) I tried to use Finite and Continuous samples , as I quoted in my previous post. I would like to use finite samples by specifying number of samples. Is there any way to work around this issue?

3) I would like to reset the counter, Can I use this function < DAQmxResetCICountEdgesDir(taskHandle As Long, channel As String) As Long > or anything to work out

Thanks

Re: Edge counting with digitial pause trigger

AdamB — Fri, 25 May 2007 12:09:05 GMT

Hi there,

Sorry you keep posting after I read the first post and start answering so I miss the second lot of questions/problems.

1) If you clear off the task correctly (not using both stop and clear) you shouldn't get that problem. If however you do still get that problem.. then you need a way to progromatically reset the device.....

DAQmx.DAQmxResetDevice(deviceName As String) will work.

2) in what sense is it not working? How many samples are you planning on outputting and at what rate? Do you get any errors?

Tha finite pulse train will use 2 counters to do this. Effectively one is set up to gate the other. If you have set this for counter 0 then ctr1 is used to gate it. If you set up as 1 the ctr0 is used to gate it. And so on in pairs. 0-1,2-3,4-5 etc. Make sure the adjacent counter is free.

3) The only way to do this is to stop the task and then start the task again.

AdamB

Re: Edge counting with digitial pause trigger

Rajaram — Fri, 25 May 2007 13:31:46 GMT

Hi there

I m sorry about lot of questions 🙂 ok. Other things are working in the program and no problem with it except pulse generation. As I have attached my program, I have not used adjacent counters in it. I have used Counter 0 for pulse generation and counter 2 for other task. So there is no problem with the setting of counters. But when i tried to use continuous and finite samples, Continuous samples seems to work fine. But finite sample is not taking pulse generated in counter 0 as trigger source ( I hope no generation of pulse at that point). I would like to generate finite pulse say with 1 number of sample. Could you look at my program and suggest me regarding this issue?

Thanks a lot