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Reading raw historical data

Learn how to retrieve raw historical values from an OPC UA server.

Basic Raw Data Reading​

Configuration​

  1. Drag an OPC UA History Read node onto your flow
  2. Configure:
    • Endpoint: Your OPC UA server
    • History Type: Raw
    • NodeId: ns=2;s=Temperature (or leave empty for dynamic)
    • Output Type: Time+Value

Simple Flow​

[ Inject ] → [ Set Parameters ] → [ History Read ] → [ Debug ]

Set Parameters (Function):

msg.nodeId = "ns=2;s=Temperature";
msg.startTime = "1 hour ago";
msg.endTime = "now";
msg.numValuesPerNode = 100;
return msg;

Output:

msg.payload: [
    { value: 23.5, sourceTimestamp: "2024-11-24T10:00:00Z" },
    { value: 23.7, sourceTimestamp: "2024-11-24T10:05:00Z" },
    { value: 24.1, sourceTimestamp: "2024-11-24T10:10:00Z" }
]

Common Use Cases​

Last 24 Hours​

msg.startTime = "24 hours ago";
msg.endTime = "now";
msg.numValuesPerNode = 1000;

Specific Date Range​

msg.startTime = "2024-11-20T08:00:00Z";
msg.endTime = "2024-11-20T17:00:00Z";

With Boundary Values​

Include values just outside the time range for continuity:

msg.startTime = "1 hour ago";
msg.endTime = "now";
msg.returnBounds = true;

Tips​

  • Use numValuesPerNode to limit response size
  • Start with small time ranges and expand as needed
  • Use relative times ("1 hour ago") for dynamic queries
  • Check statusCode in results for data quality