CIP Motion Axis - determine actual direction of motion

[ASF]

Hi all,

Just looking through the CIP_AXIS_DRIVE data type in a Logix controller to look for something that can tell me whether the current direction of motion of a CIP axis is positive or negative. Obviously I could chekc if the position is increasing or decreasing, but that takes multiple scans to reliably assess, and requires a lot of edge case catching to make sure I handle things like MRP instructions/position rollover/etc.

Does the velocity return a negative value when the axis is travelling in the reverse direction? Or is there some other element in the axis tag that can give me this info?

 

[ASF]

Does the velocity return a negative value when the axis is travelling in the reverse direction?

Update: that does appear to be the case, based on the Integrated Motion on the Ethernet/IP Network Reference Manual, page 514 but I'd still feel better if someone who's done this before could confirm. And still interested to know if there's an even simpler way of doing it!

 

[JeremyM]

I somehow ended up with an ACD sample file that had been partially unpacked and the AXIS_CIP_DRIVE data type was visible within. Here's an XML of it. You can't import it as your own type due to the sheer member count, but it might be of some use anyway.