PCS 7 V9.1 Long-Term Archiving Without Process Historian: Limits and Options

PCS 7 V9.1 OS stations can configure archive tags locally, but Siemens identifies Process Historian as the external server for plant-wide long-term archiving. An OS station's archive-tag capacity is licensed and capped at 80,000 configured tags per station; that is not a guarantee of retaining every value from startup indefinitely. For a long-lived central history and reporting, add Process Historian and size the OS archive licenses and storage for the required tag count and retention.

Understand the Archive Roles

An OS single station or OS server can archive process values and messages locally. PCS 7 V9.1 documentation distinguishes this station-level archive from Process Historian, described as the external central long-term archive. The Information Server supplies reporting over Process Historian data and, with a separate datasource-access license, can also report from data on an OS server or OS single station. These roles are separate; an OS client is supplied by an OS server and should not be confused with a standalone OS single station.

Local OS Archive Tags and PO Limits

The V9.1 Licenses and Configuration Limits manual uses “archive tags” for archived OS process-tag values. Both the normal Archiving and Long-term archiving settings count as archive tags for licensing. A WinCC Archive license is required, license quantities are additive, and each OS single station or OS server must hold the relevant license keys. Siemens specifies a maximum of 80,000 archive tags per operator station. This is an archive-tag limit, not the OS process-object (PO) limit; PO quantities are separately licensed and depend on the station type. Check the configured counts after compiling the OS rather than interpreting PO limits as storage capacity.

Use Process Historian for a Central Long-Term Archive

Process Historian collects archive values from operator stations and provides a central archive across PCS 7 projects. Siemens V9.1 documentation states that OS stations need WinCC Archive licenses, while Process Historian needs its own Process Historian license; the Process Historian does not require a second archive-tag license for the OS archive tags. The historian can serve multiple projects, while actual capacity and retention depend on configured archive load, storage and system sizing. The manual recommends installing it on a separate PC for best performance and recommends RAID for data security.

Configure the Archive Source

Decide whether the requirement is station-local cyclic history, local archive-tag configuration, or a central long-term history available across stations. Define required process values, messages, retention period, export/restore needs and reporting before selecting licenses or hardware.
In the PCS 7 project, mark only the required block parameters for archiving and select the applicable archive behavior using the configuration workflow for the installed PCS 7 V9.1 update and block library. Confirm whether the specific signal supports the intended archive setting.
Compile the OS, then use SIMATIC Manager's Tools > PCS 7 License Information and select Archive tags to inspect the configured archive-tag count. Compare the count with the licenses on the target OS single station or OS server.
If central long-term archiving is required, configure a Process Historian PC on the terminal bus and enable the corresponding Process Historian-ready component on each exporting OS station. Complete the connection and archive setup using the V9.1 Process Historian administration/configuration documentation.
Commission archiving with project-specific checks: confirm that selected values and messages arrive at the intended archive, inspect timestamps and retrieval over the required period, and test backup/restore or segment recovery procedures before relying on the archive.

Sizing the Archive

Licensing limits and storage capacity answer different questions. The 80,000 figure is the maximum configurable archive tags for one OS station in V9.1; license keys authorize a subset or the total count. It does not state how many days or years fit on disk. Retention depends on archive rate, message load, segment configuration, available storage and the chosen Process Historian hardware. The V9.1 PC Configuration manual describes the OS archive as affected by the number of values archived with Tag Logging Fast and Tag Logging Slow and warns that increasing archived data affects performance. Calculate load and storage with the applicable Siemens sizing guidance rather than inferring retention from tag count.

Verification

After OS compilation, inspect the configured archive-tag count and licensed count in PCS 7 License Information. In runtime, verify that each intended value or message is being recorded at the expected interval and can be queried over the relevant period. If using Process Historian, confirm the OS-to-historian transfer and retrieval from the central archive; validate backup and restore on representative data. Compare the measured archive growth and retrieval behavior with the retention requirement.

Limitations and Operational Precautions

The source does not provide the archive tag list, sample intervals, OS station count, message rate, available disk space or retention target, so neither a storage estimate nor a precise license quantity can be calculated. The V9.1 limit of 80,000 archive tags per operator station must not be read as unlimited retention. Siemens' V9.1 PC Configuration manual identifies Process Historian as the external long-term archive; it recommends separate hardware and RAID. A Process Historian is additional infrastructure, not a software checkbox on a client. Keep tested backups and monitor archive capacity; do not assume unbacked local archives will preserve plant history indefinitely.

Engineer FAQ

Can an OS single station archive locally without Process Historian? It can configure and license OS archive tags. Siemens describes Process Historian as the external central long-term archive; whether local OS archives satisfy a particular retention requirement depends on archive configuration, capacity and backup policy.

Is the 80,000 figure a PO limit? No. It is the maximum number of archive tags per operator station in the V9.1 licensing manual. PO licensing is separate.

Does Process Historian need a separate license for each OS archive tag? The V9.1 manual says Process Historian does not need separate archive-tag licenses for OS tags; the OS stations still need WinCC Archive licenses, and Process Historian needs its product license.

Does the archive-tag count tell me how many years I can keep data? No. Retention also depends on logging rates, message load, archive segment settings and storage capacity.

Can the Information Server replace Process Historian? The V9.1 PC Configuration manual describes Information Server as a reporting system using Process Historian data. It can also report from OS server/single-station data with an additional Datasource Access license, but it is not described as the central long-term archive.

Technical References

PCS 7 - Licenses and Configuration Limits (V9.1), §4.4–4.5 and §6.3 — archive-tag licensing, 80,000-tag per-station maximum, license checking procedure, and Process Historian licensing. Opened and reviewed.
PCS 7 - PC Configuration (V9.1), §§3.6.5 and 3.7 — Process Historian's external long-term archive role, OS single-station architecture and installation considerations. Opened and reviewed.

Related Tags

PCS 7 V9.1, OS archive, WinCC Archive, archive tags, Process Historian, long-term archiving

PCS 7 V9.1 Long-Term Archiving Without Process Historian: Limits and Options