Export setpoint handler and export registration

Like the SetpointHandler, the ExportSetpointHandler allows an external JSON message to change the value of a control point identified by the Id property of an export marker.

This handler locates target points in a station where a unique key from the cloud platform registered the points. Once the cloud platform returns a suitable identifier for a point with an export marker, this setpoint handler can apply write messages from the platform using the returned Id rather than the slot or handle ord (for example).

Export registration

The JsonExportRegistrationRouter and JsonExportDeregistrationRouter enable this behaviour of applying a unique identifier from an external system to an export marker.

This allows the cloud (or other external system) to assign it’s own identifier or primary key to export-marked points in the Niagara station, which can be used to locate them in future or include them in exports to the cloud system.

The messages should be in this format:

{
  "messageType" : "registerId"
  "niagaraId" : "h:a032",
  "platformId" : "mooseForce123"
}

{
  "messageType" : "deregisterId"
  "platformId" : "mooseForce123",
}

NOTE: This class does not use the messageType, which would be used simply to route it to this handler and so can be changed as needed.

Example

This Wire Sheet and JSON loosely demonstrate some of the routers and selectors based upon a fictional point search JSON message.

Figure 21. Json Export Registration Handler example Wire Sheet and JSON