Chapter 6 – Communication
6-4
NMBA-01 Installation and Start-up Guide
Multiple Drive Control
It is possible to connect multiple (theoretical maximum 247) drives to
one NMBA-01. Multiple Drive Control has the same control principle as
the point-to-point connection. The NMBA-01 behaves like a multiple-
address node on the Modbus network.
The Modbus network can contain several Multiple Drive Control seg-
ments. However, the total number of drives cannot exceed 247.
Note: Only one type of drive (e.g. ACS 300 or ACS 600) can be con-
nected to one Multiple Drive Control segment.
Figure 6-1 Multiple Drive Control Connection.
The Multiple Drive Control connection does not significantly add to the
DDCS communication delay. The update interval of the data in the
parameter registers is longer than in point-to-point connection, due to
the fact that each parameter value is updated from the drive’s internal
memory. The delay is most noticeable when multiple parameter
register read or write is requested.
NMBA-01
MODBUS
ADAPTER
BUS
TER MINAT ION
ON
OFF
X2
PE
SH
SHF
DG
D(N)
D(P)
TXD
RXD
XMIT
REC
ERROR
+24V
0V
ABB Drives
R
T
1
2
3
4
5
6
7
8
X2:
T
Drive 1
Drive 2
Drive n
R
T
T
R
T
T
DDCS
DDCS
DDCS
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