Modbus Rtu Protocol; Message Configuration; Id Number (Slave Address); Function Code - Taie FY100 Communications Manual

4 MODBUS RTU Protocol

4.1 Message Configuration

ID Number
1 Byte

4.2 ID Number (Slave Address)

Range: 1~255.
Master instrument identifies slave controllers by the ID Number of the requested
message. ID Number should be configuring in individual slave controller by setting
parameter "IDNO" in operation LEVEL 3.

4.3 Function Code

Function Code Contents
03 (03H) Reading multiple registers value from slave controller
(Max register count : 8)
06 (06H) Setting 1 register value to slave controller
16 (10H) Setting multiple registers value to slave controller.
(Max register count : 8)

4.4 Data

Data depends on function code.
Request message from Master instrument is include "register address", "data count"
and "setting data".
Response data from Slave controller is include "byte count", "data" and "abnormal
code".

4.5 Error Check CRC

CRC16 generation polynomial:
CRC generation step is as below:
① . CRC is initialized as FFFFH
② . Calculate XOR with 1
Y(16bit).
③ . Shift Y one bit to the right. This assumed as Y.
④ . If a carry is generated at step 3, then calculate XOR with Y and "A001H", else
jump to step 5.
⑤ . Repeat step 3 and 4, until Y is shifting right 8 times.
⑥ . Calculate XOR with next data and the low byte of Y. This is assumed as Y.
⑦ . Repeat step 3 ~5.
4 FY400/600/700/800/900 COMMUNICATION MANUAL
Function Code
1 Byte
+ +
16 15
X X X
st
data and the low byte of CRC. This is assumed as
4 MODBUS RTU Protocol
Data
N Byte
+
2 1
X
CRC
2 Byte