ABB ACS880 Firmware Manual page 35

DDCS communication module; drives with a BCU-x2 control unit require an RDCO
module.
Topology
An example connection with either a ZCU-based or BCU-based drive is shown below.
Ring and star configurations are also possible much in the same way as with the
master/follower link (see section
notable difference is that the external controller connects to channel CH0 on the
RDCO board instead of CH2. With ZCU-based drives, the channel on the FDCO
communication module can be freely selected.
Controller
T R
T = Transmitter; R = Receiver
Communication
The communication between the controller and the drive consists of data sets of three
16-bit words each. The controller sends a data set to the drive, which returns the next
data set to the controller.
The communication uses data sets 10...33. Data sets with even numbers are sent by
the controller to the drive, while data sets with odd numbers are sent by the drive to
the controller. The contents of the data sets are freely configurable, but data set 10
typically contains the control word and one or two references, while data set 11
returns the status word and selected actual values.
The word that is defined as the control word is internally connected to the drive logic;
the coding of the bits is as presented in section
(page 381). Likewise, the coding of the status word is as shown in section
the fieldbus Status word
By default, data sets 32 and 33 are dedicated for the mailbox service, which enables
the setting or inquiry of parameter values as follows:
Master/follower functionality
ACS880
(ZCU) Control unit
FDCO
T R
(page 382).
Program features 35
on page 30); the
ACS880
(BCU) Control unit
CH0
T R
Contents of the fieldbus Control word
RDCO
Contents of