Created question in FIWARE Q/A platform on 16-02-2021 at 10:02
Please, ANSWER this question AT https://stackoverflow.com/questions/66221917/adding-nested-opc-ua-variable-results-in-string-cannot-be-coerced-to-a-nodeid

Question:
adding nested OPC-UA Variable results in "String cannot be coerced to a nodeId"

Description:
Error: String cannot be coerced to a nodeId
Hi,
I was busy setting up a connection between the Orion Broker and an PLC with OPC-UA Server using the opcua iotagent agent.
I managed to setup all parts and I am able to receive (test) data, but I am unable to follow the tutorial with regards to adding an entity to the Orion-Broker using a json file:
curl http://localhost:4001/iot/devices -H "fiware-service: plcservice" -H "fiware-servicepath: /demo" -H "Content-Type: application/json" -d @add_device.json

The expected result would be an added entity to the OrionBroker with the supplied data, but this only results in a error message:

{"name":"Error","message":"String cannot be coerced to a nodeId : ns*4:s*MAIN.mainVar"}

suspected Error
Is it possible that the iotagent does not work nicely with nested Variables?
steps taken

doublechecked availability of OPC Data:

OPC data changes every second, can be seen in Broker log

reduced complexity of setup to only include Broker and IOT-agent

additional information:
add_device.json file:
{
"devices": [
{
"device_id": "plc1",
"entity_name": "PLC1",
"entity_type": "plc",
"attributes": [

{ "object_id": "ns*4:s*MAIN.mainVar", "name": "main", "type": "Number" }

],
"lazy": [
],
"commands" : []
}
]

}

config of IOT-agent (from localhost:4081/config):
{
"config": {
"logLevel": "DEBUG",
"contextBroker":

{ "host": "orion", "port": 1026 }

,
"server":

{ "port": 4001, "baseRoot": "/" }

,
"deviceRegistry":

{ "type": "memory" }

,
"mongodb":

{ "host": "iotmongo", "port": "27017", "db": "iotagent", "retries": 5, "retryTime": 5 }

,
"types": {
"plc": {
"service": "plcservice",
"subservice": "/demo",
"active": [

{ "name": "main", "type": "Int16" }

,

{ "name": "test1", "type": "Int16" }

,

{ "name": "test2", "type": "Int16" }

],
"lazy": [],
"commands": []
}
},
"browseServerOptions": null,
"service": "plc",
"subservice": "/demo",
"providerUrl": "http://iotage:4001",
"pollingExpiration": "200000",
"pollingDaemonFrequency": "20000",
"deviceRegistrationDuration": "P1M",
"defaultType": null,
"contexts": [
{
"id": "plc_1",
"type": "plc",
"service": "plcservice",
"subservice": "/demo",
"polling": false,
"mappings": [

{ "ocb_id": "test1", "opcua_id": "ns=4;s=test.TestVar.test1", "object_id": null, "inputArguments": [] }

,

{ "ocb_id": "test2", "opcua_id": "ns=4;s=test.TestVar.test2", "object_id": null, "inputArguments": [] }

,

{ "ocb_id": "main", "opcua_id": "ns=4;s=MAIN.mainVar", "object_id": null, "inputArguments": [] }

]
}
]
}
}