Comm Rtu; Address Field; Function Field; Data Field - Kipor KP310V1.0 Operation Manual

13.3 Comm RTU

This communication protocol uses RTU (remote terminals communication unit ) mode, namely
binary.

Address field

Function field

Slave address Function code
2Bytes
13.3.1 Address field
Definition of address field is the only address in MODBUS.
This communication protocol applies to one-to-one communication between PC and controller.
Low byte is before the high byte.
13.3.2 Function field
Function code is the Host operation code and reply code from Host..

13.3.3 Data field

Value is the actual bytes of data (3.2)
Data type：2Byte

13.3.4 Data CRC field

Data check uses CRC16-CCITT as standard to check all data in MODBUS except data in check
field. Low byte stands after high byte.
The host machine sends messages to MODBUS and the slave produces CRC16 code to respond;
the host and slave have to calculate CRC16 code according to CRC16 multinomial.
CRC16-CCITT produces multinomial: X^16+X^12+X^5+1，CRC16-CCITT more details in
appendix 1 & 2.
Data length
2Bytes 2Byte
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KP310V1.0 Controller Operation Manual
Data field
Data
nBytes
Data adjustment
field
CRC16
2Bytes