Communication via serial interfaces

Although today almost every industrial controller has an Ethernet connection, serial interfaces are still installed in many industrial devices. This allows, for example, for the connection of appropriately equipped sensors and actuators or extensions.

CODESYS supports serial communication with different methods depending on the device configuration:

  • COM port via function library:
    The free Serial_Communication library is supplied with the CODESYS Development System. This library is used for the simple administration of COM ports (RS232 / RS 422 / RS485) as well as the reading/writing of data from the controller application.
  • Modbus Serial (RTU) via own configurator:
    You can simply use the COM port of a CODESYS-compatible controller for Modbus communication (master/slave). For this purpose, use the seamlessly integrated Modbus configurator. If the controller does not come with the required license, this license can be obtained from the CODESYS Store subsequently.
  • SPI / I²C / 1-Wire® via runtime system component:
    Especially on standard device platforms, users can expand the available memory or functionality by means of serial data buses or communication interfaces. CODESYS supports SPI (Serial Peripheral Interface), I²C (Inter-Integrated Circuit), as well as 1-Wire thanks to components of the CODESYS Control Runtime System that can be integrated into the CODESYS Development System via corresponding drivers.
  • Own serial protocols:
    If your device has a low-level device driver that you can address in the application, you can develop your own serial communication protocols using the programming functionalities of a modern programming tool (IDE).

How can you purchase and use the communication options via serial interfaces integrated in CODESYS?

  • You are a system integrator or a user in the machine/plant construction sector or the like:
    • Use CODESYS-compatible controllers or standard device platforms that are equipped with integrated serial interfaces.
    • Download the adequate CODESYS Control SoftPLC system from the CODESYS Store that already includes a number of protocols and install it on the standard device platforms.
    • In application development, use the Serial_Communication library that is included free of charge in the scope of delivery.
    • Use device platforms that can be extended with SPI, I²C or 1-Wire using the suitable CODESYS Control runtime system.
    • Or you can develop your own protocol libraries, which you can offer to other users in the CODESYS Store. Have experienced specialists advise and support you in architectural design and implementation. Further information is available at
  • You are a manufacturer of programmable devices:
    • Implement the required communication components of the CODESYS Runtime Toolkit in your devices, as well as the possibility to license libraries per device.

For more information, please contact our Sales Team at

CODESYS brochures and information material

CODESYS - One software. All applications. Your Automation Solution.
Version: 10/2023
pdf 2 MB
CODESYS - One software. Any field of application. Your automation platform.
Version: 10/2023
pdf 2 MB
Various suppliers present CODESYS-compatible devices and exciting solutions that can be useful for your automation tasks. (Only available in german language.)
Version: 11/2022
pdf 3 MB