Modbus; General; Bus Topology; Number Of User Data, Bus Cycle Time And Data Security - ABB Advant AC500 Manual

Modbus

General

The Modbus protocol is used all over the world. The MODICON Modbus
the AC500 CPUs.
Numerous automation devices, such as PLC installations, displays, variable-frequency inverters or
monitoring systems, for instance, have a Modbus
therefore communicate with the AC500 CPUs without any problems via the serial interfaces COM1 and
COM2 (RS-232 or RS-485).
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Modbus is a master-slave protocol. The master sends a request to the slave and receives its response.
Both interfaces COM1 and COM2 can work as Modbus
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The Modbus operating mode of an interface is set with several function blocks.

Bus topology

Point-to-point with RS-232 or bus topology with RS-485. Modbus
Technical data
Supported standards
Number of connection points
Protocol
Check sum
Data transmission rate
Character frame
Maximum cable length

Number of user data, bus cycle time and data security

See relevant chapters in the operating manual
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V2
AC500 Hardware
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RTU interface by default or as an option and can
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interfaces simultaneously.
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is a master-slave protocol..
EIA RS-232 or EIA RS-485
1 master
max. 1 slave with RS-232 interface
max. 32 slaves with RS-485 interface
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Modbus (master/slave)
CRC 16
up to 19200 baud
1 start bit,
8 data bits,
1 parity bit, even or odd (optional)
1 or 2 stop bit(s)
for RS-485: 1200 m with 19200 Baud
1-43 System data
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RTU protocol is integrated in
AC500 / Issued: 05.2007