Installation manual

Danaher Motion Kollmorgen Appendix C
SERVOSTAR
®
S and SERVOSTAR
®
CD Series 110
Since encoders are incremental devices, a loss or gain of a pulse creates system
errors. Electrical noise is the single biggest factor in miss-counts. Transmitting
the signals differentially provides the largest margin of noise rejection and the
best signal fidelity. The SERVOSTAR is designed to receive only differential
signals. Some "less expensive" encoders provide TTL or "Open Collector"
signals. These are not compatible with the SERVOSTAR.
SERVOSTAR Encoder Types
The idea of obtaining velocity or position information from the series of pulses
generated from the encoder is not difficult to understand. Permanent magnet
brushless DC servo motors require commutation. As stated earlier, commutation
is simply the positioning of the electromagnetic fields in alignment with the
permanent magnet fields such that optimal torque is produced. This requires that
the motor shaft position be known at all times. The use of incremental encoders
requires some form of initialization to determine this motor shaft position at
power up. It is this commutation initialization process that can lead to confusion.
Since the SERVOSTAR supports operation with many encoder types, it must be
told which signals to expect to see and which initialization algorithm to perform.
This is the purpose of the MENCTYPE variable. The following section explains
the MENCTYPE variable and its setting for each encoder type. The next figure
shows the initialization flow chart for the various MENCTYPEs.