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Program features 33
Notes:
• The function can be enabled only when the drive is a speed-controlled follower in
remote control mode.
• Drooping (
) is ignored when the load share function is active.
• The master and follower should have the same speed control tuning values.
• The speed correction term is limited by the speed error window parameters
and
. An active limitation
is indicated by
• For a reliable ramp stop of a follower,
•
both
and
must
be set smaller than
(or speed error window control
disabled altogether by
Speed error window control enable
), and
•
.
Communication
A master/follower link can be built by connecting the drives together with fiber optic
cables (may require additional equipment depending on existing drive hardware), or
by wiring together the XD2D connectors of the drives. The medium is selected by
parameter
.
Parameter
defines whether the drive is the master or a follower on
the communication link. Typically, the speed-controlled process master drive is also
configured as the master in the communication.
The communication on the master/follower link is based on the DDCS protocol, which
employs data sets (specifically, data set 41). One data set contains three 16-bit
words. The contents of the data set are freely configurable using parameters
…
. The data set broadcast by the master typically contains the control
word, speed reference and torque reference, while the followers return a status word
with two actual values.
The default setting of parameter
is
. With this
setting in the master, a word consisting of bits 0…11 of
and
four bits selected by parameters
is broadcast to the followers.
However, bit 3 of the follower control word is modified so that it remains on as long as
the master is modulating, and its switching to 0 causes the follower to coast to a stop.
This is to synchronize the stopping of both master and follower.
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.
Summary of Contents for ACS880-x04
Page 1: ... ABB INDUSTRIAL DRIVES ACS880 primary control program Firmware manual ...
Page 4: ......
Page 18: ...18 Using the control panel ...
Page 24: ...24 Control locations and operating modes ...
Page 112: ...112 Application macros ...
Page 496: ...496 Additional parameter data ...
Page 544: ...544 Fault tracing ...
Page 602: ...602 Control chain diagrams ...