Node-red-contrib-opcua Nodes load on the OPCUA server

General
1

Hi All,
Been developing a Node-red flow as a client to commission one of my power supplies. the PSU control has an OPCUA Server.
I have quite a few variables, but not what I would say excessive at this point, but I'm getting some issues, when I deploy the flow after making a change to it, that are unexpected... I'm thinking that it could be that it is putting a heavy load on the server, but I have no experience on this.

I would be interesting to find out,
if this is a valid way of doing this or will it put a large data load on the server, specially at deploy.

I also used the subscribe function instead, with similar results.

What I notice on the node-red side is, as I keep on deploying without restarting the server, the amount of failed to connect, closed connections and attempts to reconnect increase. I even get bad node for nodes that were working fine until then.
to write I used Multiple write and this for each variable:

[
    {
        "id": "3be572c2353429f9",
        "type": "function",
        "z": "124ddb04fdd67a5f",
        "name": "T0_init",
        "func": "//let rampUpTime = 100;\nmsg.payload = 0;\n\n\nreturn msg;\n",
        "outputs": 1,
        "timeout": 0,
        "noerr": 0,
        "initialize": "",
        "finalize": "",
        "libs": [],
        "x": 340,
        "y": 120,
        "wires": [
            [
                "9e4372c7da854cf9"
            ]
        ]
    },
    {
        "id": "9e4372c7da854cf9",
        "type": "ui_text_input",
        "z": "124ddb04fdd67a5f",
        "name": "",
        "label": "T0 (uS)",
        "tooltip": "",
        "group": "c6eb6a77f74a11c6",
        "order": 1,
        "width": 0,
        "height": 0,
        "passthru": true,
        "mode": "number",
        "delay": "100",
        "topic": "topic",
        "sendOnBlur": true,
        "className": "",
        "topicType": "msg",
        "x": 580,
        "y": 120,
        "wires": [
            [
                "b3c125afc973d6fa"
            ]
        ]
    },
    {
        "id": "b3c125afc973d6fa",
        "type": "OpcUa-Item",
        "z": "124ddb04fdd67a5f",
        "item": "ns=2;s=l_setpoint_T0",
        "datatype": "Float",
        "value": "",
        "name": "l_setpoint_T0_item",
        "x": 870,
        "y": 120,
        "wires": [
            [
                "d4759c17cd85df63",
                "8118a0797d9381bc"
            ]
        ]
    },
    {
        "id": "c6eb6a77f74a11c6",
        "type": "ui_group",
        "name": "Group 6",
        "tab": "13bb6c04f22ad796",
        "order": 6,
        "disp": true,
        "width": 6
    },
    {
        "id": "13bb6c04f22ad796",
        "type": "ui_tab",
        "name": "Commisioning",
        "icon": "dashboard",
        "order": 15,
        "disabled": false,
        "hidden": false
    }
]

To Read Data I used this for each variable shoud I use the read multiple instead?

[
    {
        "id": "0bc4ad0e4dae671e",
        "type": "OpcUa-Client",
        "z": "124ddb04fdd67a5f",
        "endpoint": "8c3cfb1c3a6bfcba",
        "action": "subscribe",
        "deadbandtype": "a",
        "deadbandvalue": 1,
        "time": "200",
        "timeUnit": "ms",
        "certificate": "n",
        "localfile": "",
        "localkeyfile": "",
        "securitymode": "None",
        "securitypolicy": "None",
        "useTransport": false,
        "maxChunkCount": 1,
        "maxMessageSize": 8192,
        "receiveBufferSize": 8192,
        "sendBufferSize": 8192,
        "setstatusandtime": false,
        "keepsessionalive": false,
        "name": "IX_OPCUA",
        "x": 650,
        "y": 840,
        "wires": [
            [
                "aa8bd2ba77365fb8"
            ],
            [],
            []
        ]
    },
    {
        "id": "1119b5fc1689d885",
        "type": "OpcUa-Item",
        "z": "124ddb04fdd67a5f",
        "item": "ns=2;s=d_setpoint_T0",
        "datatype": "Float",
        "value": "",
        "name": "d_setpoint_T0_item",
        "x": 350,
        "y": 840,
        "wires": [
            [
                "0bc4ad0e4dae671e"
            ]
        ]
    },
    {
        "id": "8c3cfb1c3a6bfcba",
        "type": "OpcUa-Endpoint",
        "endpoint": "opc.tcp://128.178.126.43:4840/Anonymous",
        "secpol": "None",
        "secmode": "None",
        "none": true,
        "login": false,
        "usercert": false,
        "usercertificate": "",
        "userprivatekey": ""
    }
]

So I guess what I'm asking is:

  • Will the subscribe function on the OpcUa-Client be a better option?
  • Is the register node a better option?
  • if you subcribe, at re-deploy, do I need to unsubscribe first?
  • I'm I doing this the wrong way.
  • what is the way will put the lowest load on the server.

Hope this makes sense, let me know if you need further info.

Kind regards
Luis

2

These are (IMO) issues with the node itself. I have reported similar things recently (and I know the author has worked on them - so perhaps an improved release is iminent?)

You should check the issue tracker for the node (on GH issues) and see if your issues are listed. If not, raise issues. If they are - perhaps they note workarounds?)

It depends, but subscribe is preferable usually.

And in response to your other questions. Have you looked at the extensive example flows included with the OPC nodes? (CTRL-I --> examples --> node-red-contrib-opcua) - they may have some patterns and ideas you can use?

3

I did have a look at the examples, but is unclear, what is the best approach to use in my case.
My questions are more related to load on the server. for each read if I use a separate OpcUa- client which will create a socket. When I re-deploy will it close that socket and get a new one, or do I need to do that explicitly? The examples don't really have an explicite release of the socket. there is a keep alive tick box, which I ticked but if I don't, on subscrive it does report a keep alive status on the client.
So what I wanted to know, is this a real issue or normally this is not a problem?

about registration, the OPC labs states:
Node registration is a mechanism that can improve performance with repeatedly accessed nodes. Your code can specify the nodes it plans to access, and doing so allows the server to prepare for that. The subsequent access (such as reading, writing, or method calls) to the registered nodes can then proceed in a more efficient manner.
will this help ease the load, if that is the issue?

kind Regards
Luis