There are five function codes that set commands. Table 1 shows the different codes.
Table 1. Function Codes
|
Function Code
(Hex.)
|
Subfunction Code
(Hex.)
|
Function
|
Command Message
|
Response Message
|
|
Minimum Data Length
(byte)
|
Maximum Data Length
(byte)
|
Minimum Data Length
(byte)
|
Maximum Data Length
(byte)
|
|
03
|
-
|
Read Multiple Holding Registers
|
8
|
8
|
7
|
37
|
|
08
|
-
|
Loopback Test
|
8
|
8
|
8
|
8
|
|
10
|
-
|
Writing to Multiple Holding Registers
|
11
|
41
|
8
|
8
|
|
5A
|
-
|
Writing to Multiple Holding Registers / Reading the Register Indicated
|
11
|
41
|
17
|
17
|
|
67
|
010D
|
Reading the Contents of Non-Consecutive Holding Registers
|
10
|
248
|
10
|
248
|
|
010E
|
Writing to Non-Consecutive Holding Registers
|
14
|
250
|
8
|
8
|