The product “IIoT Libraries SL” contains numerous libraries to support different communication protocols (for example, MQTT and HTTPS) and includes tools for encoding and decoding data structures (for example, JSON and XML). Moreover, libraries with POUs for direct communication with cloud services of individual providers (AWS, Azure, etc.) are provided. The components contained in the CODESYS package are ideally suited for communication in the IIoT environment.
Libraries for communication
Web Client SL
The CODESYS software package includes a library with function blocks for communicating with a web server via HTTP or HTTPS.
The HTTP method GET requests data from a web server.
The HTTP methods POST and PUT submit data from the controller to a web server.
When using DELETE, data is deleted from a web server.
The HTTP method HEAD returns the HTTP header.
The HTTP header of a request can be extended without any restrictions. In addition, function blocks are included for HTTP basic authentication and authentication via OAuth (Version 1a and 2).
MQTT Client SL
MQTT (Message Queuing Telemetry Transport) is an open-source IoT protocol that allows for the transmission of telemetry data as messages between devices. Device communication always takes place by means of an MQTT broker (e.g. Mosquitto https://mosquitto.org/). Messages are sent and subscribed to based on topics. A topic corresponds to a path (e.g. device1/temperature). Subscribing to messages is done by specifying a topic filter. Wildcards are also permitted (+ for one level and # for multiple levels). The message format is not fixed, which means that a JSON string or any data structure can be transmitted.
With the “MQTT Client SL” library, messages can be sent from a CODESYS controller to an MQTT broker, and messages can be subscribed to based on topics.
Mail Service SL
This library contains function blocks for sending, receiving, and deleting emails by means of SMTP and POP3 protocols. Communication with the mail server can be established either encrypted (TLS) or unencrypted. A sample project demonstrates how to use the function blocks.
SMS Service SL
With this library it is possible to send, receive and delete short messages via a GSM modem.
SNMP Service SL
Supported SNMP features:
SNMP GET: Request a value.
SNMP GET_NEXT: Request a value and get the OID from the next value.
SNMP Agent: Enables devices to request values from the control (agent).
SNMP TRAP: Send and receive TRAP/INFORM telegrams.
SNMP SET: Set values via SNMP
SNMP Service SL.package contains following components:
SNTP Service SL
The library SNTP Service SL contains function blocks for easy implementation of SNTP client and server components on a CODESYS control (SNTP V3, SNTP V4). The function block
SNTPGetUTCTime can be used to request the UTC time of a SNTP/NTP server. The function block
SNTPServer can be used to build a simple SNTP server.
Function blocks (FBs) of the SNTP library:
AWS IoT Core Client SL
The “AWS IoT Core” service is a managing cloud platform from Amazon in which connected devices can work together easily and safely with cloud applications and other devices. The “AWS IoT Core Client SL” library provides function blocks for sending and receiving messages. Communication is encrypted and takes place by means of the MQTT protocol. In the AES environment, messages are typically transmitted in JSON format. The “JSON Utilities” library can be used for parsing and creating JSON files.
Azure IoT Hub Client SL
The “Azure IOT Hub” cloud service from Microsoft directly links IoT devices. (For more detailed information, refer to https://azure.microsoft.com/en-us/services/iot-hub/). The “Azure IoT Hub Client SL” library provides function blocks for sending and receiving messages. A sample project demonstrates how to use the library.
Google Cloud IoT Core Client SL
Google Cloud IoT Core will be discontinued on August 16, 2023. For more information, contact your Google Cloud account management team.
The ‘Google Cloud IoT Core’ cloud service from Google is a service for directly connecting IoT devices. (For more information, see https://cloud.google.com/iot-core?hl.)
The ‘Google Cloud IoT Core Client SL’ library provides function blocks for sending and receiving messages. A sample project demonstrates how to use the library.
JSON Web Token SL
The ‘JSON Web Token SL’ library contains a function block for creating a JWT (JSON Web Token) on the controller. For this purpose, the algorithms HS256, HS384, HS512, and RS256 are supported.
The ‘JSON Web Token SL’ package contains the following components:
IEC 61131-3 library
JSON Web Token SL (namespace JWT)
JSON Web Token SL Example.project
Programming reference as integrated CHM help
Product data sheet (German and English)
Web Socket Client SL
The WebSocket protocol allows for bidirectional communication between a client and a Web Socket Server over the Internet. Communication usually takes place via TCP port number 443 (or 80 for unsecured connections). The ‘Web Socket Client SL’ library provides function blocks for communication via the WebSocket protocol.
Libraries for reading and writing of data structures
CSV Utility SL
CSV Utility SL provides function blocks to read and write CSV files. The library contains the components
CSVReader (read a CSV file) and
CSVWriter (write a CSV file). All function blocks can be used in a classical or object oriented way. An example project demonstrates the usage of all components.
INI File Utility SL
The product “INI File Utility SL” is a library to read and write INI files. The library contains function blocks to read, write and find values of INI files. An example project shows the usage of the library and their function blocks.
Content of the package:
INI File Utility SL (Namespace:
Example project with visualization to read, write and find values of INI files
CHM help file
JSON Utilities SL
The ‘JSON Utilities SL’ library provides the following functionalities:
Read JSON files (UTF-8 and UTF-16)
Read JSON byte arrays
Write JSON files (UTF-8 and UTF-16)
Read JSON byte arrays
Search for keys, values, and child and parent elements
The data is stored in an array of structures. Data access and element search is performed by means of methods from the
JSONData function block. The simple creation of a JSON-File can be realized with funcion block
JSONBuilder. The function blocks
JSONFileReader read data in JSON format and save the values in the
JSONData function block. Writing files and byte arrays is performed by means of the function blocks
A simple REST client can be implemented easily in connection with the library ‘Web Client SL’.
XML Utility SL
The library “XML Utility SL” contains function blocks to read and write xml files or xml strings on a control. All elements of the xml file are stored in an array of structures. The library also contains function blocks to find elements by name and attribute. The usage of the library is demonstrated by two example applications.
The library contains following components:
IEC 61131-3 library
XML Utility SL (Namespace XML)
XML Utility SL Example.project
Integrated CHM programming reference
Product data sheet (de und en)