How do I write data to PI Data Archive?

There are several ways to write data to PI, depending on your data source and architecture.

PI Web API (REST)

Write a single value:

POST /piwebapi/streams/{webId}/value
{
  "Timestamp": "2024-01-15T10:30:00Z",
  "Value": 42.5
}

Write multiple values:

POST /piwebapi/streams/{webId}/recorded
{
  "Items": [
    { "Timestamp": "2024-01-15T10:00:00Z", "Value": 41.2 },
    { "Timestamp": "2024-01-15T10:15:00Z", "Value": 42.5 },
    { "Timestamp": "2024-01-15T10:30:00Z", "Value": 43.1 }
  ]
}

AF SDK (.NET)

PIPoint point = PIPoint.FindPIPoint(piServer, "MyTag");

// Single value
point.UpdateValue(new AFValue(42.5, AFTime.Now), AFUpdateOption.Insert);

// Bulk write
var values = new AFValues();
values.Add(new AFValue(41.2, new AFTime("2024-01-15T10:00:00")));
values.Add(new AFValue(42.5, new AFTime("2024-01-15T10:15:00")));
point.UpdateValues(values, AFUpdateOption.Insert);

PI Connector for UFL

For CSV, JSON, or text file ingestion:

1. Define a .ini file with parsing rules
2. Point UFL at your data files or set up a REST endpoint
3. UFL parses and writes to PI automatically

OMF (OSIsoft Message Format)

For modern IoT and edge scenarios:

[{
  "containerid": "MyContainer",
  "values": [{
    "Timestamp": "2024-01-15T10:30:00Z",
    "Value": 42.5
  }]
}]

Write Modes

Mode	Behavior
Insert	Add if no value at that timestamp
Replace	Overwrite existing value
InsertNoCompression	Write without compression evaluation
Remove	Delete the value at that timestamp

Best Practices

• Use buffering for reliable delivery — PI Buffer Subsystem queues data if the server is unreachable
• Batch writes for performance — sending 1,000 values in one call beats 1,000 individual calls
• Set appropriate point security — not every account should have write access
• Use Insert mode unless you specifically need to overwrite historical data