digital pulse output on flank of analog pulsed input.

[zikan]

I use a PCI-6024E IO-DAQ card. With this card I have to generate an analog pulsed outputsignal for another device (this is not the problem). This analog pulsed outputsignal is also connected to a PFI/TRIG pin of the card. This is to acquire data (on analog input of the card), from the other device on the falling edge of the analog pulsed signal (also no problem). Digital trigger "a" of the card is used for this purpose. (One period of an analog pulse is one measure point. So these actions are performed in a loop. The loop stops as the line is finished. And then the application goes to the next line.)

Now I have to generate a digital pulse on the same falling edge as the analog input happens. On another applicati
on, I need to do the same + put out the digital pulse also on the rising flank of the pulsed analog signal. (the digital output is needed on yet another device to switch some hardware components)

I know how to send a digital pulse. I know how to program triggered analog input on the flank on the analog pulsed signal. But I don't know how to couple them together.

I hope somebody can help me.

Thanks, zikan.

[Filipe A.]

Zikan;

I'm not sure if I got the idea of your application, but by my understanding, you need to have a TTL pulse being triggered by a falling edge of another signal, which is the clock of the Analog Input operation.

If that is the case, you can use one of the general purpose counters available on your board, configure that counter to do retriggerable single pulse generation, and have the Scan clock of the Analog Input task, routed to be the gate input of the counter. Then, at each active edge of the gate signal (the scan clock on your case), a digital pulse will be generated at the counter output pin.

Hope this helps.
Filipe

[zikan]

I think you have got it right. The TTL pulse has to be triggered by a falling edge of the signal that is put out by analog out. The same signal goes to the device AND also to the IO-card to trigger the analog input which also happens on the falling edge.

The 2 counters on the board are already taken, 1 of the 2 trigger pins is also taken. That leaves 1 trigger pin. Is it possible to use this one to trigger the incoming signal and generate a TTL pulse?
I 'm also a bit confused: difference between port and line. Which should be used for the TTL pulse?

Thanks already for your answer, zikan.

[chasan]

Dear All

I require ur help in building a VI to generate a sinle pulse(not continous) and send it a valve coil to actuate and measure the coil current back(response measurement)

For the above i used analog output and input option to send the pulse and measure the coil response but i succeeded in sending pulse and actuated it(oen/cose) but could not get the coil response back(current)

 i need to to do it simultaneouisly

I request the LabVIEW community to help in this regard i will attach the vi currently iam using

pls send me some example vi's

iam using PCI6040E and LabVIEW7.1

Thanks and Regards

D.Chandrasekaran

Engineer-LabVIEW

Emerson-IA

[MickeyD]

Hi D Chandrasekaran,

I would recommend using two finite tasks much like you have, but you need to use the same sample clock for both tasks.  There are many ways to share sample clocks but the best example is in the example finder.  It is called Multi Function Synch AI-AO.  This example shows how you can make sure that the clocks of both tasks are synched up.  There is also a triggered example.  I would recommend studying this example and then adjusting it to do the finite generation and acquisition you desire.  This way you have the same hardware driving your acquistion and generation and can avoid the software timing issues you have been dealing with.  Please let me know if you need further help with this issue.  Please try and keep your posts focused in one thread for a single issue so we can use the forumns as efficiently as possible.

Have a great day,

Michael D
Applications Engineering
National Instruments

Message Edited by MickeyD on 01-22-2007 06:49 PM

[chasan]

Hi Michel

Thanks for response

i have tried it with counetr output and analog input combination it worked nocely for some time but again its giving problem

the analog input is not acquiring the voltage samples now its acquiring and accomadating the timing changes

i will attach the vi here just give me some tips

i use same 6040card and 7.1 version

Thanks

Chandrasekaran

[MickeyD]

Hi Chandrasekaran,

I think you have a good idea.  I think you would get better behavior if you used a trigger to enforce the tasks starting together.  Otherwise sometimes the Analog input might occur before the counter starts.  If you have a question about how I changed your code I also looked at the counter and made it a finite pulse generation.  Please let me know if you have further questions.

Have a great day,

Michael D
Applications Engineering
National Instruments

[chasan]

Hi Michael

Thanks for the input

But i have a query do i need to give any external connections(trigger) to the trigger source or simply i can choose some trigger and run it

suggest me some way

Chandrasekaran