14.3.2 Modbus Interface
The Modbus communication is via RS485 interface, see descriptions on RS485+
and RS485- in chapter 8.1 "Wiring Diagram" on page 41 and chapter 8.3.2
"Control Terminals" on page 54.
14.3.3 Modbus Function and Message Format
Supported functions
The main function of Modbus is to read and to write parameters. Different func-
tion codes decide different operation requests. Modbus functions managed by
EFC x610 and their limits are shown in the table below:
Code Function name Broadcast Max. value of N
3 = 0x03 Read N register words NO 16
6 = 0x06 Write one register word YES –
8 = 0x08 Diagnosis NO –
16 = 0x10 Write N register words YES 16
23 = 0x17 Read/write N register words NO 16
Tab. 14-3: EFC x610 Modbus functions and limits
'Read' and 'Write' are considered from the prospect of the master
station.
Modbus message formats are different according to the function codes shown
below.
Slave
No.
0x03
Address of 1
st
word
Number of words CRC16
Hi | Lo Hi | Lo Lo | Hi
Tab. 14-4: Function 3_Request from the master
Slave
No.
0x03
Number of bytes
1
st
word value
– Last word value CRC16
Depends on
master request
Hi | Lo – Hi | Lo Lo | Hi
Tab. 14-5: Function 3_Response from the slave
Slave
No.
0x06
Address of word Value of word CRC16
Hi | Lo Hi | Lo Lo | Hi
Tab. 14-6: Function 6_Master request and slave response (in same format)
EFC x610 Series Bosch Rexroth AG
Communication
DOK-RCON03-EFC-X610***-IT05-EN-P
259/389
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