Part Two: Principle; Modbus Overview; About This Chapter; Protocol Implementation - 3onedata GW11 Series User Manual

Modbus gateway

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The MODBUS Serial Line protocol is a Master-Slaves protocol. At the same time, only

one master node is connected to the bus, and one or more child nodes (the maximum

number is 247) are connected to the same serial bus.A MODBUS communication is

always initiated by the master. The slave nodes will never transmit data without

receiving a request from the master node. The slave nodes will never communicate

with each other. The master node initiates only one MODBUS transaction at the same

time.

The master node issues a MODBUS request to the slave nodes in two modes:

Unicast modeBroadcast mode



The serial link diagram of master and slave is as follows:

Hyperlink

11.1 Protocol implementation

11.2 Master and slave working state diagram

11.3 Modbus communication principle

11.4 Transmission mode

11.5 Modbus basic architecture diagram

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Part Two: Principle

(I)GW11XX Modbus User Manual

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