Skip to content
machbase-neo
JSH
opcua

opcua

Since v8.0.73

The opcua module provides an OPC UA client API for JSH applications.

Client

OPC UA client object.

Creation
new Client(options)
  • Returns: Client
  • Throws missing arguments if options is omitted.
Options
OptionTypeDefaultDescription
endpointstring""OPC UA endpoint (opc.tcp://host:port)
readRetryIntervalnumber100 (clamped to 100 if lower)Retry interval for read() in milliseconds
messageSecurityModenumberMessageSecurityMode.NoneSecurity mode. See MessageSecurityMode
Usage example
 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23

const ua = require("opcua");
const nodes = [
    "ns=1;s=NoPermVariable",
    "ns=1;s=ReadWriteVariable",
    "ns=1;s=ReadOnlyVariable",
    "ns=1;s=NoAccessVariable",
];

let client;
try {
    client = new ua.Client({ endpoint: "opc.tcp://localhost:4840" });
    const values = client.read({
        nodes,
        timestampsToReturn: ua.TimestampsToReturn.Both,
    });
    values.forEach((v, idx) => {
        console.println(nodes[idx], v.status, v.statusCode, v.value, v.type);
    });
} catch (e) {
    console.println("Error:", e);
} finally {
    if (client !== undefined) client.close();
}

close()

Closes the client connection.

Syntax
close()
  • Returns: undefined

read()

Reads values from the given node list.

Syntax
read(readRequest)
Parameters
Return value

Error behavior:

  • Throws missing argument if argument count is not exactly one.
  • Throws missing nodes when nodes is empty.

write()

Writes one or more node values.

Syntax
write(...writeRequest)
Parameters
Return value

Error behavior:

  • Throws missing argument when no argument is provided.
Usage example
 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22

const ua = require("opcua");

let client;
try {
    client = new ua.Client({ endpoint: "opc.tcp://localhost:4840" });

    let rsp = client.read({ nodes: ["ns=1;s=rw_bool", "ns=1;s=rw_int32"] });
    console.println("read response:", rsp[0].value, rsp[1].value);

    rsp = client.write(
        { node: "ns=1;s=rw_bool", value: false },
        { node: "ns=1;s=rw_int32", value: 1234 },
    );
    console.println("write response error:", rsp.error, ", results:", rsp.results);

    rsp = client.read({ nodes: ["ns=1;s=rw_bool", "ns=1;s=rw_int32"] });
    console.println("read response:", rsp[0].value, rsp[1].value);
} catch (e) {
    console.println("Error:", e);
} finally {
    if (client !== undefined) client.close();
}

ReadRequest

PropertyTypeDefaultDescription
nodesstring[]List of OPC UA node IDs to read
maxAgenumber0Maximum acceptable cache age in milliseconds
timestampsToReturnnumberTimestampsToReturn.NeitherTimestamp return policy

ReadResult

PropertyTypeDescription
statusnumberOPC UA status code (uint32)
statusTextstringStatus text
statusCodestringStatus code name (for example, StatusGood)
valueanyRead value
typestringValue type name (for example, Boolean, Int32, Double)
sourceTimestampnumberUnix epoch timestamp in milliseconds
serverTimestampnumberUnix epoch timestamp in milliseconds

WriteRequest

PropertyTypeDescription
nodestringTarget node ID
valueanyValue to write

WriteResult

PropertyTypeDescription
errorError|nullWrite error
timestampnumberResponse timestamp (Unix epoch milliseconds)
requestHandlenumberOPC UA request handle
serviceResultnumberOPC UA service result code
stringTablestring[]OPC UA string table
resultsnumber[]Per-node status code array

MessageSecurityMode

  • MessageSecurityMode.None
  • MessageSecurityMode.Sign
  • MessageSecurityMode.SignAndEncrypt
  • MessageSecurityMode.Invalid

TimestampsToReturn

  • TimestampsToReturn.Source
  • TimestampsToReturn.Server
  • TimestampsToReturn.Both
  • TimestampsToReturn.Neither
  • TimestampsToReturn.Invalid

OPCUA Client

This example implements a collector that connects to an OPC UA server, reads system metrics, and stores them in the database.

Flow

  1. OPC UA integration: use the opcua module to connect to opc.tcp://localhost:4840 and read node values such as sys_cpu, sys_mem, and load1.
  2. Periodic collection: use setInterval() to read data every 10 seconds.
  3. Data ingestion: store collected values in the EXAMPLE table (name, time, value).

Data collector

Save the script as opcua-client.js, then run it in the background from the JSH terminal.

jsh / > opcua-client
jsh / > ps
┌──────┬──────┬──────┬──────────────────┬────────┐ 
│  PID │ PPID │ USER │ NAME             │ UPTIME │ 
├──────┼──────┼──────┼──────────────────┼────────┤ 
│ 1044 │ 1    │ sys  │ /opcua-client.js │ 13s    │ 
│ 1045 │ 1025 │ sys  │ ps               │ 0s     │ 
└──────┴──────┴──────┴──────────────────┴────────┘
  • opcua-client.js
 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42

opcua = require("opcua");
process = require("process");
machcli = require("machcli");

const nodes = [
    "ns=1;s=sys_cpu",
    "ns=1;s=sys_mem",
    "ns=1;s=load1",
    "ns=1;s=load5",
    "ns=1;s=load15",
];
const tags = [
    "sys_cpu", "sys_mem", "sys_load1", "sys_load5", "sys_load15"
];
const dbConf = { host: '127.0.0.1', port: 5656, user: 'sys', password: 'manager' };
const sqlText = `INSERT INTO EXAMPLE (name,time,value) values(?,?,?)`;
const uaClient = new opcua.Client({ endpoint: "opc.tcp://localhost:4840" });
process.addShutdownHook(()=>{
    uaClient.close();
});
setInterval(()=>{
    const ts = process.now();
    const vs = uaClient.read({
        nodes: nodes,
        timestampsToReturn: opcua.TimestampsToReturn.Both
    });
    var dbClient, conn;
    try {
        dbClient = new machcli.Client(dbConf);
        conn = dbClient.connect();
        vs.forEach((v, idx) => {
            if( v.value !== null ) {
                conn.exec(sqlText, tags[idx], ts, v.value);
            }
        })
    } catch (e) {
        console.println("Error:", e.message);
    } finally {
        conn && conn.close();
        dbClient && dbClient.close();
    }
}, 10*1000);

Simulator server

To test opcua-client.js, you need an OPC UA server that provides system metric nodes. If you do not have a real environment, use the simulator from the repository below. It provides sample data such as sys_cpu, sys_mem, load1, load5, and load15 to validate collection and visualization flows.

Follow the instructions in the repository to set it up.

https://github.com/machbase/neo-server/tree/main/jsh/native/opcua/test_server

After starting the simulator, run opcua-client.js and the OPC UA client will connect and collect data.

Last updated on
netos