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SI-Ethernet User Guide
139
Issue: 3
Sa
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Master request data
Slave response data
7.2.8
FC06 – Write single register
This function code writes a single 16-bit value to a register. The normal response is an echo of the
request (unless an exception occurs) returned after the parameter has been written.
The register address can be a 32-bit parameter address but only the lower 16 bits of the value will
be written.
Master request data
Slave response data
Example
To write the value 12345 to drive parameter
0.20.001
(transaction ID = 42) using standard
addressing:
Byte
Hex
value
Description
Byte
Hex
value
Description
0-1
00 2A
Transaction ID (42)
0-1
00 2A
Transaction ID (42)
2-3
00 00
Protocol ID (0=TCP/IP)
2-3
00 00
Protocol ID (0=TCP/IP)
4-5
00 06
Length (Bytes=6)
4-5
00 0F
Length (Bytes=15)
6
FF
Unit identifier (FF= Drive)
6
FF
Unit identifier (FF= Drive)
7
03
Function code (3)
7
03
Function code (3)
8-9
47 E4
Start register (20.20)
8
0C
Data length (Bytes=12)
10-11
00 06
Number of registers (6)
9-12
?
Pr
0.20.021
data
13-16
?
Pr
0.20.022
data
17-20
?
Pr
0.20.023
data
Byte
Description
Byte
Description
7
Function code 0x06
7
Function code 0x06
8
Start register address
(MSB)
8
Start register address
(MSB)
9
Start register address
(LSB)
9
Start register address
(LSB)
10
Register data
(MSB)
10
Register data
(MSB)
11
Register data
(LSB)
11
Register data
(LSB)