allowedFunctions

Type: JSON object
Required: No

"allowedFunctions": {
   "returnType": "tchmi:general#/definitions/String",
   "requiredArguments": [
      { 
         "type": "tchmi:general#/definitions/Number" 
      }
   ],
   "requiredWaitMode": "Synchronous"
}

For attributes with the data type:

"type": "tchmi:framework#/definitions/Function"

These properties can only be used for "Function" type attributes. This property determines which functions are allowed for the attribute. This means that when configuring the attribute, only those functions are displayed that meet the defined criteria.

Further parameters are possible and can be specified per instance in the engineering.

Attributes:

• returnType {string}: Determines which TwinCAT HMI data type may be returned by the function.
• requiredArguments {array of JSON objects}: Determines which TwinCAT HMI data types the functions may have as parameter values. The parameters mentioned here are set by the control.
• requiredWaitMode {enum string}: Determines in which mode (synchronous, asynchronous) the function may be executed (Synchronous, Asynchronous).

For example, one the Beckhoff controls that uses this property is LinearGauge, namely for the ValueFormat in order to restrict the functions that can format the values of the gauge.