Architecting Long-Term Archiving with SIMATIC Process Historian in PCS 7

To archive plant alarms, events, and process values for periods exceeding one year in SIMATIC PCS 7, you must deploy SIMATIC Process Historian (PH) on a dedicated server node. Process Historian cannot be co-located on an OS Client or OS Server due to Microsoft SQL Server resource contention and database throughput requirements. While Siemens Industrial PCs (such as SIMATIC IPC647D or IPC847D) are pre-certified, standard commercial enterprise servers (HP ProLiant or Dell PowerEdge) with hardware RAID arrays, redundant power supplies, and validated licensing packages are fully supported.

Architecture of Long-Term Archiving in SIMATIC PCS 7

In SIMATIC PCS 7 systems, the local Operator Station (OS) database engine is optimized for high-speed, short-term circular archiving. Standard OS Server circular archives (WinCC Tag Logging and Alarm Logging) retain live data for typical operational horizons ranging from a few days to several months before older database segments are overwritten.

When regulatory compliance (such as FDA 21 CFR Part 11 or environmental emission monitoring) mandates archiving historical data for 1 year, 5 years, or indefinitely, Siemens provides SIMATIC Process Historian (6ES7652-7AX58-0YB0). Process Historian acts as a centralized, plant-wide historian that continuously pulls segmented archive data from multiple redundant OS Server pairs, SIMATIC BATCH (6ES7657-0XX08-1YB0), and SIMATIC Route Control over the terminal bus via Microsoft Message Queuing (MSMQ) and stores it in an enterprise Microsoft SQL Server database.

Why Process Historian Requires a Dedicated Server Station

A frequent architectural question is whether Process Historian can be installed on an existing OS Client or OS Server to minimize hardware footprint:
* Resource Contention: Process Historian requires an enterprise-scale instance of Microsoft SQL Server configured to manage terabytes of compressed time-series and alarm data. Running PH on an active OS Server introduces severe I/O bottlenecks and memory competition that can crash the real-time WinCC runtime engine.
* OS Client Incompatibility: OS Clients run on client operating systems (e.g., Windows 7/10 64-bit) that do not support the server-class operating systems and SQL Server database instances required by Process Historian.
* Separation of Concerns: Operating PH on a dedicated node ensures that analytical queries, large report exports from SIMATIC Information Server, and deep historical queries never degrade critical real-time plant supervision.

Hardware Selection: Siemens Industrial PCs vs Commercial Enterprise Servers

Process Historian can be deployed on either Siemens industrial hardware or third-party commercial enterprise hardware satisfying Siemens minimum specification guidelines:

Evaluation CriteriaSiemens Industrial PC (e.g., IPC647D / IPC847D)Commercial Enterprise Server (HP ProLiant / Dell PowerEdge)Certified Part Numbers6ES7660-5... / 6ES7661-1... (Pre-installed PH)Commercial server models meeting CPU/RAM/RAID specsOperating SystemWindows Server 2012 R2 / 2016 / 2019 Standard 64-bitWindows Server Standard / Datacenter 64-bitStorage ArchitectureHardware SAS RAID Controller (RAID 1 OS, RAID 5/6 Data)Hardware Enterprise SAS/NVMe RAID (Dual Controller)Industrial RuggednessHigh shock/vibration tolerance; dust filtering; 24/7 industrial ratingRequires clean, climate-controlled server room environmentWarranty & SupportUnified Siemens automation support and long-term availabilityDirect hardware vendor support contract (e.g., HP CarePack)

Table 1: Hardware comparison for SIMATIC Process Historian deployment.

Process Historian Sizing and Licensing Structure

Configuring a long-term archiving system requires specific software and capacity licenses:
* Process Historian Basic Package: 6ES7652-7AX58-0YB0 (Provides base server installation, SQL Server runtime license, and initial archive tags).
* Archive Tag Expansion Licenses: Expanding beyond base tag limits requires cumulative Archive Tag expansion packages (6AV6372-2DF07-0AX0 or 6ES7652-7AX...).
* OS Server PH Ready Components: Included with standard PCS 7 OS Server licenses; forwards data to PH via background synchronization services.
* SIMATIC Information Server: Optional web reporting client package (6AV6372-2CF07-0AX0) to generate compliance reports from historical data. Always validate final license quantities, archive sizing, and MLFBs with an authorized Siemens distributor.

Verification

To confirm proper Process Historian installation and long-term data transfer:

Open the Process Historian Management Console on the PH server.
In the navigation tree, inspect the connected OS Server nodes: verify that each OS Server reports status Active with a green indicator.
Check Database Status: confirm that the primary SQL Server database is online and actively writing current segments.
On an OS Server, verify that the PH Ready service is running without errors in PH_Ready.log.
Open SIMATIC Information Server web portal: query process values and alarm messages from 6 months ago to verify retrieval from the long-term archive.

Limitations and Operational Precautions

Never install third-party antivirus software or backup agents that lock active SQL Server data files (.mdf, .ldf) during runtime; configure explicit exclusion rules for Process Historian database directories.
Configure regular automated database backup schedules to external NAS or network backup targets; unmanaged SQL Server transaction logs can fill disk volumes and halt archiving.
Ensure all terminal bus nodes, OS Servers, and Process Historian servers are synchronized to a common plant clock master (NTP) to maintain chronological integrity.

Engineer FAQ

Can Process Historian run in a virtualized environment (VMware ESXi)?

Yes. Siemens fully supports SIMATIC Process Historian on VMware vSphere / ESXi and Microsoft Hyper-V, provided dedicated CPU cores, fixed RAM reservations, and dedicated high-performance virtual disks (thin provisioning prohibited) are allocated.

What happens to OS data if Process Historian goes offline for maintenance?

The PH Ready service on each OS Server buffers unsynchronized archive records locally in temporary disk cache (swap files) until communication restores, after which it automatically backfills the Process Historian database.

Do I need separate WinCC archive licenses on the OS Server if using Process Historian?

Process Historian licensing manages the long-term historical tag count, but the OS Server still requires sufficient local OS RT PO / WinCC archive capacity to log tags locally before transmission.