Program features 31
Note: When the master is ramping down to a stop, the follower observes the
decreasing reference but receives no stop command until the master stops
modulating and clears bit 3 of the follower control word. Because of this, the
maximum and minimum speed limits on the follower drive should not have the same
sign – otherwise the follower would be pushing against the limit until the master finally
stops.
Three words of additional data can optionally be read from each follower. The
followers from which data is read are selected by parameter 60.14 M/F follower
selection in the master. In each follower drive, the data to be sent is selected by
parameters 61.01…61.03. The data is transferred in integer format over the link, and
displayed by parameters 62.28…62.36 in the master. The data can then be
forwarded to other parameters using 62.04…62.12.
To indicate faults in the followers, each follower must be configured to transmit its
status word as one of the above-mentioned data words. In the master, the
corresponding target parameter must be set to Follower SW. The action to be taken
when a follower is faulted is selected by 60.17 Follower fault action. External events
(see parameter group 31 Fault functions) can be used to indicate the status of other
bits of the status word.
Block diagrams of the master/follower communication are presented on pages 434
and 435.
Construction of the master/follower link
The master/follower link is formed by connecting the drives together using either
• shielded twisted-pair cable between the XD2D terminals of the drives*,
*This connection cannot co-exist with, and is not to be confused with, drive-to-drive (D2D)
communication implemented by application programming (detailed in Drive application
programming manual (IEC 61131-3), 3AUA0000127808 [English]).
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