PCI 6229

[Aida]

Hi,

I have  a "10 MHz" pulse train signal and I would like to use my PCI-6229 M series DAQ board to read this signal.

1- Is it possible to read such a high frequency input with this DAQ board?

   (the manual says the DO/DI sample clock freq is 0-1 MHz)

2- As I understand I am able the PFI lines to be the counters In/out pins. And they can handle 100 MHZ input/output. Does this mean, I can use the PFI lines to input

my 10 Mhz signal?

3- what I would ultimately like to do is to count the number of pulses coming in in a certain interval (basically would like to use the internal clock for that)

can some one please tell me that first if this is feasible (considering the high frequency) and if yes, How I can count the number of pulses?

thanks a lot,

look forward to hearing from you!

-A

[Ayman K]

Hello Aida,

It seems that you have a pulse train and you want to measure the events (pulses) of this incoming pulse train. This is easily done with the use of counters. The digital lines in the M series board are used to measure/generate the state of a digital pulse (whether it is on or off) however the counters' sole functionality is to measure the frequency of digital signals. This includes time measurments (period measurement, semi period, and events). The counters on your M series boards are 32 bit counters and they can definitely handle 10MHz signals. As a start, LabVIEW ships with an example program that does just that (Help -> Find Examples -> Hardware Input/Output -> DAQmx -> Counter Measurements -> Count Digital Events -> Count Digital Events.vi). I hope this helps. Please don't hesitate to post here if you have any further questions.

Ayman Kabire

[Aida]

Hello Ayman,

thanks for your reply.

A few more questions:

1- Basically what I am doing is inputting a pulse train to a circuit that I have designed and would like to monitor the output of this circuit which ideally is the same digital pulse! however, the signal may not be a perfect pulse train due to some inductance/capacitance/etc. that are in my circuit. What would be the best way to check for that?

should I input that to a digital line of the DAQ board and then monitor it? or to the analog line? I am not sure about the analog line because it has 250kS/s rate

2- does counting pulse require two counters? or only one? if it's only one, can I use one counter to generate my pulse train that goes to my external circuit and than use another counter to count the pulses coming out of my circuit?

thanks so much,

-A

[Aida]

I have one more question on the digital count example:

the manual says: " the counter counts edges on its source after the counter is armed"

can you please tell me what "arming" means? and where in program the counter is so called armed?!

thanks,

-a

[Ayman K]

Hello Aida,

Sorry for taking a bit long to answer your post. Below are the responses:

1. How distorted do you think your signal is going to be after passing through the circuit due to inductances and capacitances? The reason I am asking is because if the distortions are not significant and the TTL signal is still within specs, then you could still use the counter to count the edges (specs include rise/fall time and minimum width of your pulses). If the signal is very distorted, then you could use your digital lines to look at the signal. Obviously, the analog inputs won't work because they are limited in their sampling rate and you won't see a purely recovered signal.
2. Counting events requires only one counter. You can definitely use the other counter for generation.
3. The term "Arm" was extensively used in traditional DAQ (older DAQ driver) and all it means is when the counter starts its operation (i.e. counter waits for a start trigger, when it gets the trigger it is called ARMED, in other words we called the trigger the arm start trigger). In your case, calling the DAQmx start task will arm the trigger.

Please let me know if you have any further questions.

Ayman Kabire