timing while needing more thn 2 clocks inboard

[Bou]

I am using BNC-2120 to do the timing things, first I generate a anolog pulse whose falling edge is going to trigger another pulse which is digital to be genrated, and then the third pulse will be generated at the second pulse' falling edge. I found there was some sub-second delay when I get the second pulse, it's very serious because all the actins should be finished at microsecond level. Is there any solution to do the timing not using the computers' clock since there are only two internal clock on the BNC-2120, but I need one more?

[Filipe A.]

Hello;

The only way to have a accurate timing DAQ task is by using the internal Timebase of the device to clock the tasks. In case you use any Software timed operation, your accuracy will rely on the OS, being therefore system dependent.

For your specific application, the best way to go about that is to use the analog output pulse triggering one of the counters, and to have the output of that counter triggering the second counter.

Both counters should be configured as retriggerable pulse generation.

Hope this helps.
Filipe A.
Applications Engineer
National Instruments