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Installation and Start-up Guide for NMBP-01
6-1
Chapter 6 – Communication
This chapter describes the Modbus Plus communication on ACS 600 drives.
Introduction to Modbus
Plus
Modbus Plus is a 1 MBit/s, transformer-coupled network. The transformer
coupling isolates all the nodes galvanically from the network.
Modbus Plus is designed for Modicon PLCs, and the services closely corre-
spond to the PLC architecture. The ACS 600 drive ‘ looks like’ a Modicon
PLC on the network.
Program Paths
Modbus Plus network always uses five address fields for addressing nodes on
the network. Unused ones must be set to zero. The purpose of these fields is
device-dependent.
Examples of addresses are:
•
PLCs. Only one address, which is the node number on the Modbus Plus
network
•
Bridge/Mux. Two or three fields. First one is the node number on the Mod-
bus Plus network. The second one is the serial port number. The third one
is the slave number if in network mode.
•
ACS 600. Two fields. The first field is the node number on the Modbus
Plus network. The second number is internal program path number 1 – 8.
This multilevel addressing allows the user to build a large and extensive net-
work, tying together individual segments with Bridges.