using two counters: one for regenerable pulse generation, one as a counter

[JieWei]

I am new to use counters. I am using a NI PCI-6110 multifunction DAQ card. I want to count a digital pulse input (to the PFI 2 connector) , and also using the input to trigger another counter to generate pulses. So, I configured the first counter (task 1) to generate digital pulses with PFI2 as trigger source and retriggerable attribution; and configured the other counter (task 2) to count the number of edges of the digital signal with .... But after the two tasks started, the first task generated an error 50103 (Possible reason(s): NI Platform Services:  The specified resource is reserved. The operation could not be completed as specified.) Attached is the block diagram. Thanks.

[Kevin_Price · Accepted solution]

Your board uses the very-old-by-electronics-standards DAQ-STC counter chip which kinda secretly requires *both* counters working together to make a finite pulse train.  It's not actually secret if you read the right parts of the right docs, but it's not hard to miss if you don't know you should be looking.  It's been quite a while since I did much with those counters, but I have this nagging thought that they may not support retriggerable finite pulse train generation at all.  I'd caution you to at least double-check this.

Anyway, that's the reason for the error.  The finite pulse generation task uses not only the counter you specify but it also needs the other one to help it.  A couple newer generations of counter chip (NI-TIO, DAQ-STC2) continued to have this same limitation, but the *most* recent one no longer does.

The X-series boards use the "NI-STC3" chip which give you 4 user-programmable counters instead of 2, *AND* each one can generate finite pulse trains without using a helper counter.  You may want to pair one of these up with your 6110, assuming you need the 6110's simultaneous analog sampling capabilities.

-Kevin P