Adding a Standalone OS Single Station to Redundant S7-400H Systems in SIMATIC PCS 7

In SIMATIC PCS 7 systems, adding an autonomous Operator Station (OS Single Station) to communicate directly with an existing redundant S7-400H controller without routing through a central OS Server requires industrial PC hardware, a fault-tolerant S7 Named Connection, and dedicated single-station runtime and communications licensing. Engineers can choose between hardware-accelerated ISO communication using a CP 1623 card with S7-REDCONNECT or software-based SOFTNET-IE S7 REDCONNECT over standard network adapters. Final software packages, PO counts, and hardware part numbers must be verified against official Siemens catalogs and an authorized distributor quotation.

OS Single Station vs Server-Client Topology

In conventional large-scale SIMATIC PCS 7 plants, supervisory architecture is organized around dedicated OS Servers (often redundant pairs) that manage controller communication and serve graphic screens to thin or thick OS Clients. However, certain plant operations—such as remote boiler rooms, water treatment units, or autonomous packaging areas—require an independent Operator Station capable of operating even if central servers or the plant Terminal Bus fail.

An OS Single Station functions as both client and server within a single chassis:
- It maintains its own local WinCC runtime database, alarm logging, and trend archives.
- It connects directly to the controller plant bus via a fault-tolerant S7 connection (Named Connection) to both CPU A and CPU B of the S7-400H or CPU 410-5H pair.
- It operates completely independently of other operator stations on the plant network.

Hardware Interfaces: Hardnet CP 1623 vs Softnet Industrial Ethernet

When establishing a fault-tolerant connection to an S7-400H controller, engineers must select the appropriate communications interface:

Hardnet Communication (CP 1623 / CP 1613):
Uses a dedicated communications processor (PCIe card CP 1623, MLFB 6GK1162-3AA00).
Offloads ISO transport protocol and redundancy supervision entirely onto the card's onboard microprocessor.
Provides deterministic, bumpless switchover (<100 ms) during controller or cable failure.
Requires the SIMATIC NET S7-REDCONNECT software license (6GK1716-0HB13-0AA0).
Standard architecture for legacy S7-400H controllers (e.g. CPU 414-4H, CPU 417-4H).
Softnet Communication (Standard Industrial Ethernet NIC):
Uses standard commercial or onboard Gigabit Ethernet network interface cards (Intel-based).
Protocol stack and redundancy monitoring execute within the Windows operating system kernel.
In modern PCS 7 releases (PCS 7 V8.1/V8.2/V9.0 with CPU 410-5H), supported via SIMATIC NET SOFTNET-IE S7 REDCONNECT (6GK1704-0HB13-0AA0).
Reduces hardware procurement costs by eliminating specialized CP cards.

Software Licensing and Process Object Requirements

Operating an OS Single Station on a redundant plant requires distinct licensing components:

OS Single Station Runtime License: Authorizes the WinCC runtime engine on a standalone workstation (e.g., base package providing 250 Process Objects).
OS Runtime PO Expansion: If the plant area controlled by this station contains more than 250 POs, cumulative PO expansion packs (+100, +500, +1,000 POs) must be installed.
S7-REDCONNECT License: Mandatory for maintaining fault-tolerant 4-way S7 connections to both redundant S7-400H CPUs.
WinCC Archive Expansion: If local historical trending exceeds the base 512 archive tags, an OS Archive license (e.g., 1,500 or 5,000 archive tags) is required.

Procurement Schedule and Equipment Architecture Table

The following table details typical hardware and licensing components required to deploy an OS Single Station on a redundant S7-400H system:

Component RoleDescription / SpecificationExample Hardware / MLFBLicense ClassificationIndustrial PC HardwareRack-mount or desktop IPC (e.g., SIMATIC IPC547E / IPC647D)6AG4104-4AA10-0XX0Hardware DeviceCommunications CardCommunications Processor PCIe for Plant Bus (Hardnet option)6GK1162-3AA00 (CP 1623)Hardware InterfaceRedundancy ProtocolSIMATIC NET S7-REDCONNECT for Hardnet CP 16236GK1716-0HB13-0AA0Communications Runtime LicenseOS Runtime SoftwareSIMATIC PCS 7 OS Software Single Station (Base 250 PO)6ES7658-2AA18-0YA0Core OS Runtime LicenseCapacity ExpansionSIMATIC PCS 7 OS Runtime License Extension (+500 PO)6ES7658-2XA00-0XH0Cumulative PO Runtime LicenseProcess Historian / ArchiveSIMATIC PCS 7 OS Archive (1500 Archive Tags)6ES7658-2EA00-0YB0Archive Runtime License

Commercial Accuracy Disclaimer: Software order numbers (MLFBs), package structures, and hardware compatibility prerequisites vary across PCS 7 versions and hardware platforms. System integrators must confirm exact software entitlements and licensing requirements against the official Siemens Catalog CA 01 and obtain an authorized Siemens distributor quotation prior to purchasing.

Verification

Verify OS Single Station communication with redundant S7-400H:
1. In NetPro on the ES, verify the S7 connection type is configured as 'Fault-tolerant S7 connection' pointing to CPU 0 and CPU 1.
2. Compile and download the network configuration and OS project to the new IPC.
3. Open SIMATIC NET > Station Configurator on the OS PC; confirm CP 1623 and Application objects show state 'RUN'.
4. Open WinCC Channel Diagnosis in runtime; confirm both connection lines to the H-CPU show status 'OK' with green checkmarks.
5. In runtime, simulate a network cable disconnect from CPU 0; verify that process graphics continue updating seamlessly via CPU 1 without alarm interruptions.

Limitations and Operational Precautions

Key architectural and operational constraints:
- Adding an OS station requires updating the STEP 7 multiproject and downloading the updated NetPro connection table; performing connection downloads to an active S7-400H controller must be coordinated to prevent unintended communication bumps.
- An OS Single Station does not share historical archive data with central OS Servers unless configured with OpenPCS 7 or linked to Process Historian.
- PO licenses purchased for an OS Single Station cannot be pooled with or shared across central OS Server pairs.

Engineer FAQ

Can I use standard office PC hardware for an OS Single Station?

While standard commercial PCs can run WinCC, Siemens industrial PCs (such as IPC547 or IPC647) are strongly recommended due to long-term component availability, certified electromagnetic compatibility, and pre-tested driver stacks.

Can I create an 'OS Reference' to duplicate an existing station?

Yes. If the new OS Single Station displays the identical plant hierarchy and screens as an existing station, you can configure it as an OS Reference in SIMATIC Manager, eliminating redundant compilation time.

Does the OS Single Station require an engineering license?

No. The engineering station (ES) performs the project compilation. The OS Single Station only requires runtime software, PO capacity, and communication licenses.