UDT to JSON API reference

Enable and disable the UDT-to-JSON service

Navigate to the config folder.
Open the services.json configuration file.
Enable or disable the UDT-to-JSON service by editing the "siemensUDT2JSON" block of the "transformServices" object.
1. Set the "enabled" property to true to enable the UDT-to-JSON service.
  OR set the "enabled" property to false to disable the UDT-to-JSON service.
```
{
	"serviceName": "siemensUDTServiceopcua",
	"serviceLibrary": "siemensudtservice.dllopcservice.dll",
	"enabled": true
}
```
2. Save any changes.
3. Restart the server for the changes to take effect.

Request examples

Note

The listed examples require a UDT schema that matches the serialized data structure that your PLC is publishing to an MQTT topic, see Obtain and convert the UDT schema.

For a list and detailed description of the specific properties in the "createTransform" action, see createTransform.

The Siemens UDT-to-JSON transform does not have "target" parameters because it writes to the same integration table that it reads from. The table is specified by the "configureTopic", "alterInput", or "alterIntegrationTable" actions which invoke this transformation.

The Seimens UDT-to-JSON transform reads binary data from one field (column) and writes JSON data to a different field of that table. Both the "inputFields" and "outputFields" arrays should contain exactly one field each, and those two fields should be different from each other.

Minimal request

{
    "authToken": "ReplaceWithValidToken",
    "api": "hub",
    "apiVersion": "1.0",
    "action": "createTransform",
    "params": {
        "transformName": "PLCData_transform",
        "transformActions": [
            {
                "transformService": "siemensUDT2JSON",
                "transformActionName": "siemensUdtPayloadToJSON",
                "inputFields": [
                    "source_payload"
                ],
                "outputFields": [
                    "aValidFieldName"
                ],
                "transformParams": {
                    "schema": "ReplaceWithConvertedUDTSchema",
                    "rootTypeName": "ReplaceWithRootName"
                }
            }
        ]
    }
}

Maximal request

{
    "authToken": "ReplaceWithValidToken",
    "api": "hub",
    "apiVersion": "1.0",
    "action": "createTransform",
    "params": {
        "transformName": "PLCData_transform",
        "transformActions": [
            {
                "transformService": "siemensUDT2JSON",
                "transformActionName": "siemensUdtPayloadToJSON",
                "inputFields": [
                    "source_payload"
                ],
                "outputFields": [
                    "temperature"
                ],
                "transformParams": {
                    "schema": "ReplaceWithConvertedUDTSchema",
                    "udtDebugTracing": false,
                    "rootTypeName": "ReplaceWithRootName"
                }
            }
        ]
    }
}

Response examples

Minimal response

{
    "result": {},
    "requestId": "00000007",
    "errorCode": 0,
    "errorMessage": ""
}

API reference for Siemens UDT to JSON transform method

API referenceJSON hub APIJSON transformsiemens udtudt to json transform

`"params"`

The "params" property is an object that contains an action's parameters. Each action defines its own required and optional properties.

Property summary

Table 1. "params" property summaries

Property	Description	Default	Type	Limits
transformActions	specifies `"transformAction"` objects	Required - No default value	array of objects
transformName	specifies the name of a transform process. The name cannot be one of the FairCom-provided transform names	Required - No default value	string	1 to 64 bytes

`"transformActions"`

The "transformActions" property is an optional array of "transformAction" objects. It defaults to an empty array.

"inputFields"

The "inputFields" property is a required array containing one or more of the fields in the integration table. The FairCom server sends the value of each of these fields to the transform action as its primary input.

Typically a transform action only needs one input field and the most common input field is "source_payload".
When a transform is applied to an integration table, the server automatically adds missing fields to the table. Thus, any field can be the source of a transform. A transform can only put the result of a transform in a field specially created to hold the transform's output value. In other words, a transform's output field cannot be a field that is built into the table or a field that is being used by another transform.
When a transform has multiple transform actions, you typically daisy chain the "output" field of one transform action to be either the input field of another transform or the field that is being written to by another transform.

"mapOfFieldsToProperties"

The "mapOfFieldsToProperties" property is a required array of "mapOfFieldsToProperties" objects. It defaults to an empty array.

        "mapOfFieldsToProperties": 
        [
        {
          "propertyPath": "In1",
          "fieldName": "In1"
        }
        ]