---
title: "RP2040-HAT-MODBUS-C"
url: "https://maker.wiznet.io/mason/projects/rp2040-hat-modbus-c/"
markdown_url: "https://maker.wiznet.io/mason/projects/rp2040-hat-modbus-c/md"
type: "WCC: WIZnet Created Content"
author: "Mason Lee"
editor: "WIZnet"
editor_url: "https://maker.wiznet.io/"
original_author: "Mason Lee"
license: "MIT license (MIT)"
published: "2024-03-10"
language: "en"
tags: ["W5500"]
hardware: ["WIZnet W5500-EVB-Pico", "WIZnet W5100S-EVB-Pico"]
likes: 0
views: 5180
comments: 0
source: "WIZnet Makers (https://maker.wiznet.io/)"
---

# RP2040-HAT-MODBUS-C

> Modbus TCP RTU/ASCII on WIZnet Pico boards

Original author: Mason Lee

## Components

- **WIZnet W5500-EVB-Pico** x 1 ([docs](https://docs.wiznet.io/Product/Chip/Ethernet/W5500/w5500-evb-pico))
- **WIZnet W5100S-EVB-Pico** x 1 ([docs](https://docs.wiznet.io/Product/Chip/Ethernet/W5100S/w5100s-evb-pico))

## Documents and links

- [RP2040-HAT-MODBUS-C Code](https://github.com/wiznetmaker/RP2040-HAT-MODBUS-C) (code)

## Article

## **RP2040-HAT-MODBUS-C**

This project is a Modbus TCP RTU/ASCII example code that runs on the W5500-EVB-Pico or W5100S-EVB-Pico.

<https://docs.wiznet.io/Product/iEthernet/W5100S/w5100s-evb-pico> <https://docs.wiznet.io/Product/iEthernet/W5500/w5500-evb-pico>

### **Set the CMakeLists**

Set the PICO_SDK_PATH in RP2040-HAT-MODBUS-C/CMakeLists.txt
Refer to the documentation below for more information.
<https://www.raspberrypi.com/documentation/microcontrollers/c_sdk.html>

```plaintext
if(NOT DEFINED PICO_SDK_PATH)
    set(PICO_SDK_PATH ${CMAKE_SOURCE_DIR}/libraries/pico-sdk)
    message(STATUS "PICO_SDK_PATH = ${PICO_SDK_PATH}")
endif()
```

If you are using the W5100S-EVB-Pico board, make the following changes. The default is W5500-EVB-Pico.

```plaintext
# Set ethernet chip
set(WIZNET_CHIP W5100S)
```

### **Set Timer**

If you have a different MCU or a different clock, you will need to set the Timer. This example is set to a timer of 20khz.
RP2040-HAT-MODBUS-C\port\modbus\src\mbtimer.c

1/20khz = 50us

```cpp
add_repeating_timer_us(50, vMBPortTimersCallback, NULL, &g_mb_timer);
```

### **Set Modbus Serial**

In this example, the UART1 TX : 4, RX : 5 Pins are converted to Modbus Serial.
Baudrate is 19200. RP2040-HAT-MODBUS-C\port\modbus\inc\mbserial.h

```cpp
#define UART_MODBUS uart1
#define UART_MODBUS_TX 4
#define UART_MODBUS_RX 5
#define UART_MODBUS_BAUDRATE 19200
```

### **Build**

RP2040-HAT-MODBUS-C

```plaintext
mkdir build
cd build
cmake -G "NMake Makefiles" ..
nmake
```

I tested using modbus poll/slave tools.
modbus poll : <https://www.modbustools.com/modbus_poll.html>
modbus slave : <https://www.modbustools.com/modbus_slave.html>

Modbus Pool Connect :
![Modbus Poll connect.png](https://github.com/wiznetmaker/W5X00_STM32F411_Modbus/raw/main/Images/Modbus%20Poll%20connect.png)

Modbus Slave Connect :
![Modbus Slave connect.png](https://github.com/wiznetmaker/W5X00_STM32F411_Modbus/raw/main/Images/Modbus%20Slave%20connect.png)

Test Result :
![Test Result.png](https://github.com/wiznetmaker/W5X00_STM32F411_Modbus/raw/main/Images/Test%20Result.png)

---

Source: https://maker.wiznet.io/mason/projects/rp2040-hat-modbus-c/