Introduction

RS-232 is a widely used communication protocol for serial data exchange between devices, offering simplicity and reliability in industrial applications. Industrial Shields PLC families, including the ESP32 PLC, M-Duino PLC, and Ardbox PLC, support RS-232 communication, making them versatile tools for automation projects.

This guide walks you through the hardware and software setup required to enable RS-232 communication with these PLCs. From configuring switches to establishing proper connections and writing your first lines of code, this tutorial ensures you can effectively utilize RS-232 in your projects.

Additionally, we provide examples to help you quickly start using RS-232 communication, whether you're sending, receiving, or monitoring data. For further details, explore the technical features of ESP32 PLC Family, M-Duino PLC Family and Ardbox PLC Family.

Hardware

Switch configurations

To use the RS-232 communication, configure the communications switch as follows:

• For ESP32 PLC Family:
• • Set switch 2 of A zone to OFF
• For M-Duino PLC Family:
• • No switch configurations needed
• For Ardbox PLC Family:
• • Select RS on Top zone switch
    

Connections

The connections between devices are GND with GND, TX with RX and RX with TX.

Software

Install the industrialshields-avr board on the Arduino IDE. You can do it by following this tutorial.

Select your board and model:

1. For M-Duino PLC Family: Tools > Board > Industrial Shields AVR Boards > M-Duino [Extension] family and Tools > Model > M-Duino [Module]
2. For Ardbox PLC Family: Tools > Board > Industrial Shields AVR Boards > Ardbox [Extension] family and Tools > Model > Ardbox [Module] HF+ w/HW RS-485
3. For ESP32 PLC Family: Tools > Board > Industrial Shields ESP32 Boards > ESP32 PLC Family and Tools > Model > ESP32 PLC [Module]

Include the RS232 library in your code and use RS232 to refer to the RS-232 port.

Make sure that the baudrate is the same in the all the devices.

Some basic functions

1. Begin RS232 port:

RS232.begin(BAUDRATE);

2. Send data:

RS232.write(tx);

3. Check if data is available to read and read the data

if (RS232.available()) {
	byte rx = RS232.read();
}

Check out the examples on Arduino IDE at Examples > RS-232.