Function Codes; Lrc - SMC Networks HRSH Series Operation Manual

HRX-OM-Q033
Chapter 4 MODBUS communication function

4.6 Function codes

NO Code
1 03(03h) Read holding registers
2 06(06h) Preset single register
3 16(10h) Preset multiple registers
4 23(17h) Read/write 4x registers
1：Broadcast is not supported.

4.7 LRC

 Calculation example
LRC message for calculation
Calculation
Sending message
4.6 Function codes
4-10
Table 4.6-1 shows function codes to read or write register.
Table 4.6-1 Function codes
Name
Reading multiple registers
Writing registers
Writing multiple registers
Reading/writing multiple registers
LRC checks the content of the message other than [:] of START and
[CR][LF] of END. The sending side calculates and sets. The receiving side
calculates based on the received message, and compares the calculation
result with the received LRC. The received message is deleted if the
calculation result and received LRC do not match.
Add up the byte number of the message consisting of 8 consecutive bits. The
result except the carry (overflow) is converted to 2's complement.
Function
 1
]0106000B00FE
○Addition
01h＋06h＋00h＋0Bh+00h+FEh＝110h
○Object
110h→10h
○complement of 2
10h→EFh→F0h
LRC is F0h
[:]0106000B00FEF0[CR][LF]
HRSH Series