User guide: Cross-site federation and collection redundancy
Cross-site federation exposes remote capabilities. This section explains collection ownership and recovery checks. Released dedicated IO installers do not support remote databases and do not provide a cross-PC primary/standby setup.
Select capabilities per direction
Select IO, Alarm, Trend and Screens separately in Sites.
- Configure a local connection and select the capabilities the local site needs. Configure the reverse direction separately when required.
- IO scope selects remote devices, Alarm and Trend expose remote results, and Screens opens remote screens.
- Scripts, event records and retention remain managed per runtime unit. See Sites and Remote data for the detailed workflow.
The active collector for a PLC
Within a Runtime Unit, one active IO Owner collects and writes each PLC definition. Independent Sites do not coordinate automatically; avoid duplicate definitions for the same physical PLC.
- Inspect connection, collection and owner information in device details. Consumers use collected state without opening independent PLC connections.
- The runtime requires candidates in one runtime unit with matching applied configuration, drivers, credentials, connectivity, license and capacity. These requirements alone do not establish an installer-supported cross-PC standby deployment.
- Federation alone, or matching device names, does not create collection takeover between independent database domains.
Observe failure and recovery
After recovery, check the actual collector and new values; do not assume another PC has automatically taken over.
- Inspect owner, device connectivity and Tag quality to distinguish service failure, network loss and temporarily invalid values.
- After collection recovers, wait for valid new values, then check alarms and trends. Unavailable periods retain quality states and historical gaps.
- Reconcile unconfirmed writes through request records and subsequent collection before deciding what to do next. Restored connectivity does not prove a previous command executed.
Dedicated IO deployment limits
Windows/Linux dedicated-node provides IO only. Prepare PostgreSQL/Redis managed outside the installer, a schema, and local loopback addresses. Cross-machine data services are unsupported.
- For multiple PCs, install independent sites and connect their capabilities. Do not point a dedicated-node installation at another PC’s database.
- Before installing dedicated IO, verify the role, same-machine data services, prepared schema, protected resource policy, drivers, network access and licensing.
- Cross-PC automatic takeover requires a deployment plan verified for the delivered version.
