Delta ASDA-A3 Series, Руководство пользователя

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MODBUS Communication ASDA-A3
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Communication data structure
Definitions for the data frames in the two modes are as follows:
ASCII mode:
Start Start character ‟:” (3AH)
Slave Address Communication address: 1 byte consists of 2 ASCII codes
Function Function code: 1 byte consists of 2 ASCII codes
Data (n-1)
Data content: n word = 2n-byte consists of n x 4 ASCII codes, n ≤ 10 …….
Data (0)
LRC Error check: 1 byte consists of 2 ASCII codes
End 1 End code 1: (0DH) (CR)
End 0 End code 0: (0AH) (LF)
In ASCII communication mode, the message starts with a colon ‟:” (ASCII code: 3AH). The ADR
consists of two characters in ASCII code. The message ends with CR (Carriage Return) and LF
(Line Feed). The codes for data such as communication address, function code, data content,
and LRC error checking (LRC: Longitudinal Redundancy Check) are between the start
character and the end code.
RTU mode:
Start A silent interval of more than 10 ms
Slave Address Communication address: 1 byte
Function Function code: 1 byte
Data (n-1)
Data content: n-word = 2n-byte, n ≤ 10 …….
Data (0)
CRC Error check: 1 byte
End 1 A silent interval of more than 10 ms
In RTU communication mode, the message starts and ends with silent intervals. The codes for
data such as communication address, function code, data content, and CRC error checking
(CRC: Cyclical Redundancy Check) are between the start and end intervals.