ABB AC500 V3 Hardware Manual page 1000

System assembly, construction and connection
AC500 (Standard) > Connection and wiring
2.6.4.8 Modbus RTU connection details
The Modbus RTU protocol is implemented in the AC500 processor modules.
Modbus is a master-slave (client-server) protocol. The client sends a request to the server(s)
and receives the response(s).
Available serial interfaces can work as Modbus interfaces simultaneously.
The Modbus client operating mode of an interface is set with the function block
COM_MOD_MAST.
Technical data
The Modbus operating mode and the interface parameters are set in the .
Table 205: Description of the Modbus protocol
Parameter
Supported standard
Number of connection points
Protocol
Operating mode
Address
Data transmission control
Data transmission speed
Encoding
Max. cable length for RS-485 on COM1 for
AC500 CPU
Bus topology Point-to-point with RS-232 or bus topology with RS-485. Modbus is a master-slave protocol.
For further information on Modbus see chapter .
1000
CAUTION!
Risk of communication faults!
When using inappropriate cables, malfunctions in communication may occur.
Only use network cables of the categories 5 (Cat 5, Cat 5e, Cat 6 or Cat 7) or
higher within PROFINET networks.
3ADR010278, 3, en_US
Value
See
1 client
Max. 1 server with RS-232 interface
Max. 31 servers with RS-485
Modbus
Client/server
Server only
CRC16
From 9,600 bits/s to 115,200 bits/s
1 start bit
8 data bits
1 or 2 stop bits
1 parity bit
)
1.200 m at 19.200 baud
2022/01/31