PCI 6025E and External Trigger

[Pallavi]

hi, I am using PCI 6025E to generate a Retriggerable Pulse on its Counter.
I am using the external trigger pulse coming from an encoder as input on PFI1. I want a counter output which will be high for every 14th pulse and low for the remaining 13 pulses of the external trigger signal supplied.
So, to generate the pulse on Counter 0, i am using the pulse specs(raw) control. It has controls: Delay (edge), pulse(edge) and timebase. Does the timing of external trigger decide the timebase and if yes then what value do i need to input in the "timebase" control. Then i guess i can decide the count of "Delay" and "Pulse" depend on the timebase.

Please help.

[Andy F.]

Pallavi,

The options for the time base when using the timebase input for the pulse specs (raw) input are 10 kHz and 20 MHz, which are the timebases of the board.  I was able to find this information by using the DAQ help as well as opening the Set Pulse Specs.vi to see the block diagram.  The raw timebase option is then the input to Counter Set Attribute.vi that I was able to find some good information in the help about.  Hope this helps!

Andy F.

[Pallavi]

Hello,

Thanks! I saw the Labview help and from the VIs i gathered that the timebase values u mentioned are for internal timebase. I think if i am using an external trigger then i need to put timebase as 1. And what value of timebase should i consider to calculate the Delay and Pulse count (required to select Low time and High Time  of Cntr0 output pulse.)

Regards,

Pallavi. 

[Andy F.]

The timebase that you specify as the source is the timebase that you would use to calculate the delay and pulse values.  So in this case you selected PFI1 to be your external source, so you can use the external timebase for these values. 

Hope this helps!

Andy F.

[Pallavi]

Hi!
So, to use the external timebase,do i need to put 1 as timebase ?.I saw some VIs and Labview Help which said that if you are using internal timebase u can put 0 in timebase and if u are using External source as timebase , u need to put 1 in timebase. Or do i put the actual value of the timebase?..say 50ns.

Regards,
Pallavi.

[Andy F.]

I can understand the confusion.  I would recommend opening the Set Pulse Specs.vi and looking at the block diagram carefully.  If you notice the Counter Set Attribute.vi which sets the timebase has the "timebase n" as the attribute value number.  This means that you can only select the boards internal clocks.  To allow access to the PFI pins you could change the attribute value number from "timebase n" to "PFI n" and then select 1 as the timebase in the raw settings.  I would recommend that you save this VI as something different than the original to prevent future unpredictable behavior. 

Hope this helps!
Andy F.

[Pallavi]

Hello,

I tried making it PFI n.but when i run the VI..it gives me the error: invalid parameter.

Pallavi.

[embedded systems engineer]

Hi Ms Pallavi,
Iam raghav from india bangalore,if you need any assistance reach me imagination1103@rediffmail.com
Iam too working in labview.


Regards
Raghav

[Sean_C.]

Hello Pallavi,

Can you create a simple VI which demonstrates this error?  I would like to see if I can reproduce it on my machine.

Also, your code will give me a better idea of what you are trying to do. 

Is there any reason why you are not using NI-DAQmx instead of Traditional NI-DAQ?  Programming is much more straightforward with NI-DAQmx.

Regards,
Sean C.

[Pallavi]

Hi,

Well. i am new to Labview.So, how do i create a VI to demonstrate the error? Also, since we already had a PCI6025E in the lab, and i could use it for counter operations, i am just using the same instead of getting a new  DAQmx.

When i change the parameter to PFIn, it gives me the error 10123: Invalid paramID used.

I am  attaching my VI for reference. I am supplying the external trigger input at PFI1. I  want to set the values for pulse specs(raw) such that the counter will generate a pulse every 14th pulse of my trigger input. So, i want to know what timebase it considers with a external trigger and what values i need to input in the pulse specs(raw) control.

Pallavi.