JSON

Use the JSON type to exchange structured data between your HMI and PLC. This type enables you to transmit complex, hierarchical data structures in a standardized format.

JSON variables are currently limited to custom elements, properties, or actions built with the HELIO SDK. Typical use cases include graphs, charts, or other components that require more complex data structures.

Specification

• A JSON variable is represented as a String data type on your PLC.
• The string must contain valid JSON syntax according to the JSON specification.
• The JSON data must be serialized (converted to a string representation) before being written to the PLC string variable.
• When reading from the PLC, HELIO automatically parses the string back into a JSON object for use in your custom elements.

Example

If you want to send this JSON object:

{
  "pressure": 1013,
  "status": "normal"
}

Your PLC string variable would contain:

'{"pressure":1013,"status":"normal"}'