23.1. modbus rtu master
23.1.1. Overview
This project demonstrates the modbus rtu master function
In this example project, one board serves as rtu master and the other board serves as rtu slave. The master sends a read holding register and waits for the slave to respond to the request data.
23.1.2. Note
When using uart for modbus communication and communicating with an rtu slave, you must reset the slave first and then the host.
23.1.3. Board Setting
Please refer to the description in the specific development board {ref}` pin description <board_resource>` section.
Connect the modbus uart pins of the two boards.
The two boards must be connected to the GND of both sides to share the ground to ensure signal transmission.
23.1.4. Running the example
Run slave first, then master
When the project runs correctly, the serial terminal will output the following information:
modbus rtu master example
recv slave msg len:25
Hold Registers[0~9]:0x0000 0x0001 0x0002 0x0003 0x0004 0x0005 0x0006 0x0007 0x0008 0x0009
recv slave msg len:25
Hold Registers[0~9]:0x0000 0x0001 0x0002 0x0003 0x0004 0x0005 0x0006 0x0007 0x0008 0x0009
recv slave msg len:25
Hold Registers[0~9]:0x0000 0x0001 0x0002 0x0003 0x0004 0x0005 0x0006 0x0007 0x0008 0x0009
recv slave msg len:25
Hold Registers[0~9]:0x0000 0x0001 0x0002 0x0003 0x0004 0x0005 0x0006 0x0007 0x0008 0x0009
recv slave msg len:25
Hold Registers[0~9]:0x0000 0x0001 0x0002 0x0003 0x0004 0x0005 0x0006 0x0007 0x0008 0x0009