OPC resources

Open Platform Communications (OPC) resources are tag lists that can be used when configuring the OPC UA Subscriber and Reader modules instead of typing each tag manually for the module in CONNECT flows.

When using an OPC resource, all the tags in the resource are used by the OPC UA modules. Any tags entered manually in CONNECT flows or loaded dynamically from a flow message are added to the list of tags in the resource file.

Code example: OPC resource as a JSON array

The following code example shows the format of OPC resources as a JSON array where each tag is assigned to an object.

[

{

"NodeId": "ns=4;i=1244",

"path": "/4:Boilers/4:Boiler #1/4:PipeX001/4:FTX001/4:Output",

"customType": "tempSensor",

"customScale": 1.5

},

{

"NodeId": "ns=4;i=1245",

"path": "/4:Boilers/4:Boiler #1/4:PipeX001/4:FTX001/4:Output",

"customType": "pressureSensor",

"customScale": 1.5

}

]

How to reference OPC resources

The NodeId property is mandatory and should follow the OPC UA syntax for flow runtime IDs.
You can add custom metadata to every object in the resource file that becomes part of the outgoing message.

Any other properties added are included in the output message for the tag. Custom properties can be used for the following purposes:

• Add metadata that allows filtering and grouping of tags in other modules in the flow.

• Applied per tag to specific scaling or conversion parameters used by other modules to change the values.

This format is also used when loading tags dynamically from flow messages and matches the output produced by the OPC UA Browser module.

Note: The output of the OPC UA Browser contains several properties in addition to NodeId and these will be treated as custom properties by the Subscriber and Reader modules. If you don’t want to have these properties in the output, remove them using the Property Mapper module and place this module between the Browser and Subscriber/Reader module.