Serial communication means data is sent one bit at a time at a specified BAUD rate (bits per second).
Both signaling types use serial communication.
How an Arduino can Speak over an RS485įirst, let’s talk about Arduino and RS485.Īlthough Arduino supports serial communication through its built-in UART (Universally Asynchronous Receiver/Transmitter), it uses TTL (Transistor-Transistor Logic), not RS485. In this post, I'll talk about adding an Arduino to an RS485 network and programming it to function as a Modbus slave device. So, how can you program an Arduino to act as a Modbus device? There is a twist, however. The devices with which the PLC is communicating are Arduinos. A situation arises where you have a system that includes a PLC, an HMI, and some peripheral devices. The HMI displays some information to a user and allows for some basic control and the PLC manages data collection and communication through an RS485 network using a Modbus RTU protocol.Įasy, right? Many PLCs already support RS485 and Modbus communication and only require a few functions blocks.
