cDAQ Arm Trigger

[user50]

I'm now venturing into the DAQmx library trying to take advantage of the counters, triggers, and synch while I'm using a cDAQ 9178 and the 9401 module.  I need a little help figuring out how the counters and triggers operate.

Purpose

I will have a DO (the write task in the cDAQ Counter.vi) that causes the DUT to send a CAN message some mseconds later.  I want to have a counter that starts counting on the DO and stops counting on a pulse generated from that CAN message (which will be from an 8473s).  This is all to get the delta time from fault to message.

So in this sample cDAQ Counter.vi I have a DO task, and a counter that I configured currently just with the ArmStart trigger.  If I start the counter task, the counter counts and the ArmStart is useless.  If I don't start the counter task, the counter does not count and the ArmStart does nothing.  My approach is to figure this out before I add any pause or stop function to the counter.

I'm at a loss.  Any advice appreciated.

Bryan

[Sean_F]

Hi Bryan,

What you're describing is a two-edge separation task. More info here. You can find example programs under Help » Find Examples » Hardware Input and Output » DAQmx » Counter Measurements » Two-Signal Edge-Separation to get you started. You're going to want to start your DO task on a trigger. This trigger will also start the two edge separation task (it'll be wired into First Edge input of CI Two Edge Separation). The pulse returned from your CAN device will be connected to the Second Edge input of CI Two Edge Separation. Hope this helps!

Sean