Bosch Rexroth EFC 3600 - Page 176

13.2.3 ModBus Function Codes and Message Format
Supported Functions
The main function of ModBus is to read and to write parameters. Different function co‐
des decide different operation requests. MouBus functions managed by EFC 3600 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
Fig.13-3: EFC 3600 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
Fig.13-4: 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
Fig.13-5: Function 3_Response from the slave
Slave No. 0x06
Address of word Value of word CRC16
Hi | Lo Hi | Lo Lo | Hi
Fig.13-6: Function 6_Master request and Slave response (in same format)
Slave No. 0x08
Test word 1 Test word 2 CRC16
Hi | Lo Hi | Lo Lo | Hi
Fig.13-7: Function 8_Master request and Slave response (in same format)
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Communication Protocols
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