MODBUS architecture and application methodology.pptx

modbus architechture

1. There are three types of MODBUS communications 1.MODBUS ASCII 2.MODBUS RTU 3.MODBUS TCP/IP MODBUS can be used over SERIAL as well as ETHERNET cables. MODBUS-RTU SERIAL RS232 RS485 Only up to 50ft and can connect only two devices Up to 4000ft/1200mtr and 32 nodes All devices on a RTU network must use same baud rate for data transmission .Typical range is 9600 to 19200 bits per second.

2. MODBUS RTU

3. MODBUS serial communication network will work on master and slave topology. The master device issues communication commands to slave. Unless the slave receives Commands from master the slave does not transfer any data to master. There can only one master in the network and there can be a maximum of 247 slaves connected in a network. Each slave has a unique ID from 1 to 247.

4. MODBUS ADDRESSING SYSTEM