interupting pulse train when channel changes value

[VPS]

Hi,

I would like to drive a translation stage using the NI USB-6211. 

I can move the stage simply by sending a pulse train on a given digital channel. However I also have two limit switches, also connected to two digital channels. What is the best method for interupting a given pulse train when one of the limit switches becomes high. I guess there are methods which do not require a polling procedure (i.e. reading the digital channel at high speed). Ideally one would like to do this at hardware level but I guess this is not possible. All suggestions are welcome.

Thanks!

VPS

[JÞB]

VPS-

You are correct about using hardware to do this.  You do want to gate the pulse trains with the appropriate limit switch such that [signal "move plus" will only be applied while the limit switch is in its normal state.]  Having the limit switch also connected to the DI allows you to programmatically determine when the limit is reached but, it is not really great engineering to depend on the unrelated DI and SW (and both must work) to keep the stage from being overdriven.  Gating the drive signal with a transistor attached to the limit switch is a "fail-safe" approach- and demands less speed in the DI loop. 

[cheggers]

Hi VPS,

this sounds like a pause trigger to me. You can interrupt your pulse train with a digital signal. Simply paste a trigger node befor the task is started:

 You will find good examples in the NI Example Finder. Hope this helps...

Cheggers