Read historical data in Node.js

The code

const { OPCUAClient } = require("node-opcua");

(async () => {
  const client = OPCUAClient.create({ endpointMustExist: false });
  await client.connect("opc.tcp://milo.digitalpetri.com:62541/milo");
  const session = await client.createSession();

  const end = new Date();
  const start = new Date(end.getTime() - 10 * 60 * 1000);

  const history = await session.readHistoryValue(
    "ns=2;s=Dynamic/RandomDouble",
    start,
    end
  );

  for (const dv of history.historyData.dataValues.slice(0, 5)) {
    console.log(dv.sourceTimestamp.toISOString(), dv.value.value, dv.statusCode.toString());
  }

  await session.close();
  await client.disconnect();
})();

What it prints

2026-09-08T03:35:00.001Z 41.2 Good (0x00000000)
2026-09-08T03:36:00.002Z 43.8 Good (0x00000000)
2026-09-08T03:37:00.001Z 39.1 Good (0x00000000)
2026-09-08T03:38:00.003Z 44.6 Good (0x00000000)
2026-09-08T03:39:00.001Z 42.0 Good (0x00000000)

Notes

• Bound every history request. An open-ended read against a production historian is how you become the incident.
• Read ServerProfileArray before designing around history. If no historical facet is claimed, the capability is not there.
• For OEE, ask the server for TimeAverage or PercentGood over the shift window rather than streaming raw values and aggregating in Node.
• A gap in the returned series usually means the collector was down, which is itself availability data.

What breaks first

Last verified 7 September 2026 against OPC UA 1.05.07. OPC UA Connect is an educational resource and is not affiliated with the OPC Foundation.