Martin/Jochen,
The position mode I am speaking of does not use a serial bus or analog inputs. It used the step and direction or CW and CCW digital signals from the motion controller. This has become very common in Asia.
Our P-Command mode acts like an open loop stepper in the sense it doesn't try to close the position loop or do a pull-in move. But still has the ability to monitor the encoder feedback and trip on following error. Other signals used are the In Position signal. This goes from the drive to the motion controller and signals when the drive has caught up with the stream of step signals being sent to it. This can be used to improve the move complete status on our motion controller.
This is all new functionality which can be found in NI-Motion 6.1.5.
So it is a stepper board controlling a servo drive. It may sound odd, but it works.
One thing to watch for in this mode is properly sizing the motor for the application. If not, you will get a large lag (I have seen this in the > 5K counts range) between what the motion controller is commanding and what the servo drive/motor is actually doing. It does catch up at the end of a move, but if you aren't using the In Position line, you will most likely not hit your target position.
And remember in this mode, you do your servo tuning on the drive.
Rodger S.
