T&L Publications

I am working on a CNC control project and a question has come up.

A common stepper driver module has a ' DIR' input. This switches the step rotation to forward or reverse with a voltage signal from the break out board.

So the question....
Is there a 'standard' for the 'DIR' signal like + for forward, or + for reverse stepper direction?

In the practical world reversing, a stepper coil, or inverting it in the control software fixes that issue,
Also, I assume that once the stepper stops and locks, the DIR signal will not change until the next direction change, and continued same direction movement would remove the locking current and continue the steps with no DIR signal change (Think peck drilling)
My circuit needs to know if the spindle stepper is moving down or up, relative to any stopped position, so limit switches will not work.
The circuit design can easily accommodate either + or - for 'reverse' so I am just sorting out some details.

Thanks for the input...
Len

I would think DIR would stay the same or just (like its rise/fall time be completed) before current is switched to next or previous pole of motor.

Cheers,