Hello, I've used NI DAQ hardware before, but I've never used a counter. I'd like to use a counter with the quadrature encoder output from a stage to send a trigger pulse every time the stage travels a certain distance (e.g. 5um).
I plan to start the counter, move in a single direction, then stop the counter. The encoder has a resolution of 1nm, which I understand means I will get a rising edge on Ch A every 4nm. If the stages are moving at 100mm/s, this means a rising edge every 40ns, corresponding to a frequency of 25MHz.
I've looked into Counter Output Events, and it seems like they can do what I want. I would set the initial count to correspond to my output trigger interval. (e.g. 5um / 4nm = 1250 initial count). I would set the action to count down, and select the output terminal and behavior (pulse). Then I expect that every time the counter measures 1250 pulses it will output a pulse, reset, and continue counting. I plan to run the stages ~10mm with the task running, and would expect 2000 output pulses (10mm / 5um = 2000). Then I would stop the task.
Before I run off and buy some hardware, I wanted to check my understanding with the experts here.
1. How do I pick hardware that is capable of counting a rising edge every 40ns? What is the relevant spec to look for?
2. Is my understanding of Counter Output Events correct? I can count down from initial count to output a trigger and it will continue resetting until I stop the task?
Please let me know what information I've left off, and thanks for your help!