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Communication
Page 7-4
ABB Control - AC 31
1SBC 260400 R1001-b
06.99
The MODBUS frames transmitted by the master contain the following information:
- The MODBUS address of the interrogated slave (1 byte)
- The function code defining the master request (1 byte)
- The data to exchange (N bytes)
- The CRC16 control code (2 bytes)
The frame has a maximum total length of 240 bytes thereby enabling the exchange of a
maximum of 100 data words or 255 binary data.
The slave's reply contains the request confirmation, the data to be returned and also a frame
control code. The slave returns an error code in the case of an error.
Other protocol information is supplied in the annex.
Only the following MODBUS operation codes may be processed by the 40 and 50 series
central units:
Function codes
Description
In hexadecimal
In decimal
01 or 02
01 or 02
Read n bits
03 or 04
03 or 04
Read n words
05
05
Write a bit
06
06
Write a word
07
07
Fast reading of 8 bits
08
08
Diagnosis / initialization
0F
15
Write n bits
10
16
Write n words
The codes generated on error are:
Error codes
Description
01
Unknown function code
02
Address error
03
Data error
Summary of Contents for AC 31
Page 1: ...Technical Manual Advant Controller 31 40 50 Series 1SBC 260400 R 1001 b ...
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Page 130: ...Programming ABB Control AC 31 Page 5 21 1SBC 260400 R1001 b 06 99 ...
Page 182: ...Communication ABB Control AC 31 Page 7 11 1SBC 260400 R1001 b 06 99 ...
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Page 218: ...AC 31 technical documentation ABB Control AC 31 Index Page 1 1SBC 260400 R1001 b 06 99 Index ...