ABB ACS 800 Series, Firmware Manual

Page: 94 / 340

Program features
94
Master/Follower use of several drives (Only in EXT2 Control)
In a Master/Follower application, the system is run by several drives, the motor
shafts of which are coupled to each other. The Master and Follower drives
communicate via a fibre optic link. For the Master/Follower configuration to work, the
drive has to be in EXT2 control. If the Master/Follower configuration is used in EXT1,
the drive works as a stand-alone drive.
The Master drive communicates with the Follower drive through channel 2. The
channel 2 addresses are set internally in the Follower drives. The fault, torque prove
OK, safety control bits and the drive ready bits of the Follower drives are used for the
interlock in the Master drive. These interlocks work only when the drive is in EXT2
control. In EXT1 control none of these interlocks are checked and the drive works
like a stand-alone drive. The Follower drive uses the data set 44 for transmitting the
interlock status word. The Master also sends the interlock bits to the slave using data
set 43. The Master monitors if any of the Follower drives goes into the fault or limit
state and the FLWRx LIM/FLT message (where x is the Follower drive number) is
displayed in such condition. The detailed description of the fault or limit will be
available in the Follower drive.
Note : Even though the Master/Follower interlock functions are checked only in EXT2
control, the Master/Follower communication link should be active in both EXT1 and
EXT2 control. Otherwise the drives will trip on Communication fault.
The user defines the number of Follower drives in the Master drive. One Master
drive can have a maximum of four Follower drives. Note that you must configure the
Follower drives in a sequential order. In other words, if the configuration includes
one Follower drive, it is configured as Follower 1, not as Follower 2, Follower 3, or
Follower 4. Similarly, if the configuration includes two Follower drives, the correct
configuration is Follower 1 and Follower 2, not Follower 2 and Follower 3, or any
other combination. A follower drive is configured as Follower 4 only when the
configuration includes four Follower drives.