Hi, I'm having an application where I want to sample the AI input and issue the AO output based on the level of a counter measurement. The counter measures the angle of a circular movement. When the angle passes certain levels, e.g. every 30 degrees, we want to take in the AI measurement and issue the AO output. Could anyone tell me how to realize this application? Thanks!

Hi guys, I think Matt has the right idea, but rather than triggering the tasks off of the signal from the counter I would use this signal as a Sample Clock. From what it sounds like you want to update a single sample every N degrees, so all you would need to do is generate a sample clock edge based off of the encoder. One reason that this solution would be preferable to using triggers is that M series boards do not support retriggerable analog tasks. You would have to start/stop the task in order to trigger again and risk missing samples. I went ahead and put together an example on our Community Site. I admit that the block diagram might be a little messy, so if you need any help understanding what's going on don't hesitate to ask. The example will only work properly if the encoder is counting in a single direction (since it generates the sample clock based off of encoder ticks regardless of which direction they occur). Update AI/AO Every N Degrees of Encoder Measurement -John

Multifunction DAQ

event based sampling and output

Solved!

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Hi John,

Now I understand what is happening inside the loop. The CO pulse ticks is not from the motor encoder. That's why the system doesn't acquire more samples even when the motor is spinning.

I'll carry on experiments with the calculation of the control input. I hope this won't introduce too much calculation and the system would be able to update on time.

Thanks so much for the help!

-Lucy