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General Description

The CODESYS IIoT Libraries SL package contains numerous libraries for communication in the IIOT environment. Different protocols are supported, such as MQTT and HTTPS. The package also provides tools for encoding and decoding data structures (for example, INI, CSV, JSON, and XML) and function blocks for direct communication with cloud services of individual providers (for example, AWS and Azure).

You can download CODESYS IIoT Libraries SL from CODESYS Store International or CODESYS Store North America. There you will also find the data sheet for the product.


After installing the package, you will find sample projects for using the libraries in the installation directory under IIoT Libraries SL\Examples.

The following libraries are supplied with the package:

Libraries for communication:

  • Web Client SL: Communication with a web server via http or https

  • MQTT Client SL: Support of the MQTT (Message Queuing Telemetry Transport) protocol for the transmission of telemetry data as messages between devices

  • Mail Service SL: Send, receive, and delete emails by means of SMTP and POP3 protocols.

  • SMS Service SL: Send, receive, and delete an SMS by means of a GSM modem

  • SNMP Service SL: Support of the following functions: SNMP GET, SNMP GET_NEXT, SNMP Agent, SNMP TRAP, SNMP SET

  • SNTP Service SL: Build SNTP client and server applications (SNTP V3, SNTP V4).

  • AWS IoT Core Client SL: Send and receive messages in exchange with Amazon's "AWS IoT Core" cloud platform

  • Azure IoT Hub Client SL: Function blocks to send and receive messages when connecting IoT devices to Microsoft's "Azure IOT Hub" cloud service.

  • Google Cloud IoT Core Client SL: Send and receive messages in exchange with "Google Cloud IoT Core" cloud service. Important note: Google Cloud IoT Core will be discontinued on August 16, 2023. For more information, contact your Google Cloud account management team.

  • JSON Web Token SL: Create JWT (JSON Web Token) on the controller. For this purpose, the HS256, HS384, HS512und, and RS256 algorithms are supported.

  • Web Socket Client SL: Communication via the WebSocket protocol between a client and a Web Socket Server over the Internet.

Libraries to read and write data structures:

  • CSV Utility SL: Read and write CSV files

  • INI File Utility SL: Read and write INI files

  • JSON Utilities SL: Create, read, and write complex JSON files (UTF-8, UTF-16); read and write JSON byte arrays and search for keys, values, child, and parent elements

  • XML Utility SL: Read and write XML files or XML strings on the controller and to search XML elements