FAURE HERMAN FH8400, User Manual

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Chapter 5 : Modbus transmission tables
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Table n° 8 (reference address 1800h)
Table containing the Event logger data, in particular:
contents of the last record
number of the last record
number of the record to be read
Main characteritics of the transmission
•
Protocol used: Modbus RTU (8-bit binary transmission)
•
Working mode of the FH8400 : slave
•
Baud rate: 9,600 or 19,200 bauds
•
Number of bits : 8
•
Number of start bits: 1
•
Number of stop bits : 1
•
Parity : None
• Error check: CRC16
Transmission formats
A Modbus word is composed of two bytes.
Data are transmitted according to one the following formats:
•
Integer (symbol INT) : 1 Modbus word, that is 2 bytes
•
Long integer (symbol LINT) : 2 Modbus words, that is 4
bytes
•
IEEE 32-bit floating number (symbol FLOAT) : 2 Modbus
words, that is 4 bytes, constituted as follows
Exponent on 8
sign
bit
31 30 23 22
Mantissa on 23 bits
15
0