Indeed, although I've just noticed that I'm using the pins on the PIC as source and the diagram in the manual shows the controller pins as sink ie. PUL+ connected to 5VDC and PUL- to the pin on the controller. I have it the other way around, PUL+ connected to the pin (which goes high to generate pulse) and PUL- to 0VDC. I'll swap it around and do a test.

I'm using PIC16F887 to control the DM856.

Regards,
T.