Using stepper output for external clock (as encoder for position measurement)

[brian175]

Hello,

I have an application where we want to use the stepper output from a stepper controller as the external clock signal for the analog acquire.  The drive provides a connector with step out and step out inverse that is available for use with "external applications".  However, when we connect these signals directly to the PFI line for the external clock the step counts do not match the corresponding motions.  For example if we request a 25,000 step motion we only get 24,064 acquired points.  The number is very repeatable, whether we change the velocity or stepper resolution.  I believe that we may need a pull-up or pull-down resistor but not sure exactly how to wire it.

There is also a I/O return pin on the connector which we tried in place of the step out inverse, but had the exact same results.

The stepper drive is a pacific scientific automation technology group 5445

We also did confirm that the distance travelled and the resulting step count matched the requested motion (not the acquired number we got).

Thanks,

Brian

[Luke_W]

Hey Brian,

              Have you tried lowering the number of steps or changing the data type representation to something with higher precision?

Luke W