Danfoss MCO 350 Operating Instructions Manual page 97

Syncronising Controller MCO 350 Operating
Instructions
Track Error
The synchronising controller of the slave drive uses the master drive signal and the gear ratio to
calculate a reference position value for the slave drive. The deviation of the feedback position
from the calculated position is known as the track error. This is specified in quad counts. The
maximum track error is also a threshold value that defines the permitted operating area of the
synchronising controller.
Accuracy
This value specifies the permitted deviation between the master and slave at which synchronisa-
tion is still present.
PPR
Pulses per revolution.
Virtual master
If several axes are to travel in synchrony, or if the synchronisation error is so to be kept as small
as possible, it is often more advantageous not to take the reference position from a drive, but to
have a master that simulates the reference position. This has the advantage that the cycle times
of the individual drives are not added. These differences are illustrated below for the synchronous
control of three conveyor belts. First, we show the classic synchronisation procedure where the
reference value signal is taken from the preceding drive in each case.
Illustration 5.1: Synchronisation without Virtual Master
As can be seen from the diagram below, at Start, as well as with every change in speed of the
master drive, the cycle times are added. They are then compensated for again based on the control
characteristics of the controller in question.
®
MG.33.Q1.02 - VLT is a registered Danfoss trademark
5. Appendix
5
97