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5 Modbus Communication Protocol

5.1 Serial communication parameters

Modbus is a serial communication protocol, Modicon programmable logic controller (PLC) for the use of

published. It has become the industry standard communication protocols, and is now quite common

connection between industrial electronic equipment. Modbus has ex-tensive application in the industrial

field. Modbus protocol is a master / slave framework agreement. A node is the master node, other nodes

using the Modbus protocol in communication from node. Each slave device has a unique address.

S-Temp&VWC&EC-02 sensor with RS485 interface, support Modbus protocol. The communication

parameters to factory default values for: baud rate 9600 BPS, one start bit, 8 data bits, no parity, one stop

bit. Communication protocol is Modbus RTU protocol. Communication parameters can be changed by the

setup program or MODBUS command, after the communication parameters are changed, the sensor is

required to re - enter the sensor to be effective.