Arm start trigger

[mayasong]

I got two NI 6221 DAQ cards (M-series), each of which has two counters.  I want to take the readings from three counters and sychronize them.

Here, I attached the vi that I am using.  The problem is that how I can get the arm start trigger? It is stated that the arm start trigger would be better used to sychronize three signals.  Could I use vi to generate start trigger sources? Comments are greatly appreciated! Could I use functino generator to simulate the trigger source?  Thank you very much in advanced!

[MarkLe]

Hi Mayasong,

In this example, the arm start trigger is setup to check for a rising or falling edge on a specified I/O line - labelled trigger source. This will synchronize the counters, and they will start counting when the start trigger condition is met.

What event exactly do you want to start the counter acquisition on? Something from within software, or a hardware event?

If you'd like to synchronize from with a VI, you could write code (eg a function generator) to generate this pulse on an output line, then loop that back into the input you select to arm the trigger. Alternatively, you can do this with a RTSI cable connected between the two cards inside your PC.

This link (below) may help you with synchronization:

http://zone.ni.com/devzone/conceptd.nsf/webmain/6DC991028566309886256F990080A720

Hope this helps!

Mark

Applications Engineer

National Instruments