What is PI interface buffering and how do I configure it?
What is PI interface buffering and how do I configure it?
PI interface buffering (PI Buffer Subsystem or PI API Buffering) ensures no data is lost when the network connection between an interface node and the PI Data Archive is interrupted.
How Buffering Works
- The PI interface collects data from the data source (OPC, DCS, PLC, etc.).
- Data is sent to the buffer on the interface node.
- The buffer forwards data to the PI Data Archive.
- If the connection drops, data accumulates in buffer files on disk.
- When the connection restores, buffered data is automatically sent.
Types of Buffering
| Type | Description |
|---|---|
| PI Buffer Subsystem (BufSS) | Modern buffering service (recommended) |
| PI API Buffering (bufserv) | Legacy buffering for older interfaces |
Configuring PI Buffer Subsystem
- Install PI Buffer Subsystem on the interface node.
- Open PI Buffer Subsystem Admin from the Start menu.
- Add your PI Data Archive server(s) as destinations.
- Configure buffer file location and maximum size.
- Set the primary and optionally secondary (for PI Collectives) server.
Key Settings
- Buffer directory: place on a drive with sufficient space (not the OS drive).
- Max buffer file size: default 256 MB — increase for high-throughput interfaces.
- Queue send rate: adjust if network bandwidth is limited.
Monitoring
- Check the BufSS event log for connection status.
- Monitor disk usage on the buffer directory.
- PI SMT > Operation > Buffering Statistics shows buffer health.
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