Examples

Arduino/PlatformIO

5 basic examples are available for ESP32 Arduino core framework on PlatformIO:

• /client: Modbus RTU & TCP clients (2 examples)

• /server: Modbus RTU & TCP servers (2 examples)

• /bridge: Modbus RTU ↔ TCP bridge

To run them, replace the content of your main.cpp file by the provided ones. Normally, if you have already imported the library in your PlatformIO project repository (/lib directory), you don't need to modify your platformio.ini file.

ESP-IDF

The same examples as PlatformIO are available for IDF, with specific folders for each example :

• /rtu-client

• /rtu-server

• /tcp-client

• /tcp-server

• /bridge

To run them, create an IDF project using files provided in the example (CMakeLists.txt, main.cpp & WiFiSTA.hpp helper class for TCP examples). You need to have imported the EZModbus library in your project's components first (see the Installation section of this guide).

An additional example is available in /rtu-client-server-loopback: it runs an RTU Client & an RTU Server that communicate together between 2 different UART ports. It will allow you to test the basic features of the lib & communication, without any external Modbus device/app. To run this example, connect the two serial ports together in "loopback" mode, default pins (ESP32-S3):

RX1 (Pin 44) ←→ TX2 (Pin 43)
TX1 (Pin 7)  ←→ RX2 (Pin 6)

TCP examples use a Wi-Fi connection (STA) to enable networking. If you want to run the examples with your own Ethernet connection instead, just remove the Wi-Fi code and initialize your Ethernet driver before the calls to EZModbus components.

EZModbus relies on the ESP32's TCP/IP stack, it is agnostic regarding the link used (Wi-Fi, Ethernet, PPP...). TCP frames will be forwarded behind the scenes between your network interface & EZModbus through LwIP.