23.3. modbus tcp master

23.3.1. Overview

  • This project demonstrates the modbus tcp master function

  • In this example project, one board serves as tcp master and the other board serves as tcp slave. The master sends a read holding register and waits for the slave to respond to the request data.

23.3.2. Note

  • When using enet for modbus communication and communicating with an tcp slave, you must reset the slave first and then the host.

23.3.3. Board Setting

  • Connect a USB port on PC to the PWR DEBUG port on the development board with a USB Type-C cable

  • Connect the RGMII port or a RMII port of the two boards.

23.3.4. Running the example

  • Run slave first, then master

  • When the project runs correctly, the serial terminal will output the following information:

This is an ethernet demo: modbus tcp (Polling Usage)
LwIP Version: 2.1.2
Enet phy init passed !
Static IP: 192.168.100.11
Netmask  : 255.255.255.0
Gateway  : 192.168.100.1
modbus tcp master example
Link Status: Down
client connected server
Link Status: Up
Link Speed:  1000Mbps
Link Duplex: Full duplex
recv slave msg len:29
Hold Registers[0~9]:0x0000 0x0001 0x0002 0x0003 0x0004 0x0005 0x0006 0x0007 0x0008 0x0009

recv slave msg len:29
Hold Registers[0~9]:0x0000 0x0001 0x0002 0x0003 0x0004 0x0005 0x0006 0x0007 0x0008 0x0009

recv slave msg len:29
Hold Registers[0~9]:0x0000 0x0001 0x0002 0x0003 0x0004 0x0005 0x0006 0x0007 0x0008 0x0009

recv slave msg len:29
Hold Registers[0~9]:0x0000 0x0001 0x0002 0x0003 0x0004 0x0005 0x0006 0x0007 0x0008 0x0009

recv slave msg len:29
Hold Registers[0~9]:0x0000 0x0001 0x0002 0x0003 0x0004 0x0005 0x0006 0x0007 0x0008 0x0009

recv slave msg len:29
Hold Registers[0~9]:0x0000 0x0001 0x0002 0x0003 0x0004 0x0005 0x0006 0x0007 0x0008 0x0009