ABB ACS880 Firmware Manual page 73

messages over an electrical cable or fiber optic link. The master can read feedback
signals from up to 3 selected followers.
M
~
Process master
(For example)
Control word
Speed reference
Master
Torque reference
Master/follower link
DDCS
Fieldbus control
External control system
(e.g. PLC)
The master drive is typically speed-controlled and the other drives follow its torque
or speed reference. In general, a follower should be
• torque-controlled when the motor shafts of the master and the follower are
rigidly coupled by gearing, chain etc. so that no speed difference between the
drives is possible.
• speed-controlled when the motor shafts of the master and the follower are
flexibly coupled so that a slight speed difference is possible. When both the
master and the follower are speed-controlled, drooping is also typically used
(see parameter 25.8). The distribution of load between the master and follower
can alternatively be adjusted as described under
speed-controlled follower
Process
follower
Follower
DDCS
(For example)
Status word
01.01, 01.10
below.
M
~
Load share function with a
Program features 73
Speed-controlled master
Torque-or-speed
controlled follower