Configuration Of The Modbus Interface; Programming - ABB 07CR41 Operating Manual

6.2.2 Configuration of the MODBUS interface

6.2.3 Programming

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Communication
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MODBUS communication with the 40 and 50 series basic units is only allowed if the black 07
SK 51 or 07 SK 53 cables are used.
The serial interface of the 40 and 50 series basic units have a default MODBUS
configuration with the following parameters:
- Mode:
- Baud rate:
- Number of stop bits:
- Number of data bits:
- Parity:
The mode is changed via the system constant KW 00,06 (see chapter 5).
Changes to the speed, number of stop bits, data bits or parity is programmed in the PLC
program with the SINIT function (see appropriate documentation). The SINIT does not need to
be used if your application uses the standard parameters.
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The MODBUS mode remains available even if the basic unit program was stopped (the front
switch is set to OFF) when the black 07 SK 51 or 07 SK 53 cable is connected and the serial
interface is configured for MODBUS
modifications becomes available when the grey 07 SK 50 or 07 SK 52 cable is used.
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MODBUS slave unit
All the data may be read or written in MODBUS
communication management. The MODBUS
request sent by the MODBUS
recognizes the address.
The SINIT function is only required in the program when communication parameters are
changed.
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MODBUS master unit
The MODBUS function enables data read/write requests to sent to the MODBUS
The SINIT function must be used in the program if the communication parameters are
changed.
List of cross references
An exchange of MODBUS
elements:
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- The MODBUS address of the first exchanged variable
- The size of the list = the total number of variables in the list.
All the variables of the 40 and 50 series basic units, as described in the following table, can be
read or written by the master MODBUS
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MODBUS slave 1 unit
9,600 baud
1
8
None
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communication. The programming mode for tests and
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. A program is not required for MODBUS
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slave basic unit automatically converts the
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master basic unit and returns a message as soon as it
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data is in the form of a table which is defined by the following
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.
6 – 8
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slaves .
Advant Controller AC 31 / Issued: 01.99