WinCC PC Runtime: Selecting V7, Unified, and Flexible Advanced

1. Overview: Three Generations of Siemens PC-Based HMI

Siemens has shipped three distinct runtime architectures that can execute HMI logic on a standard industrial PC rather than on a dedicated Panel-style device. In order of decreasing age they are:

1. SIMATIC WinCC V7 / V7.x (originally "WinCC Classic") – a 32/64-bit Windows SCADA suite for plant-floor stations, tag-based configuration in the WinCC Explorer, and C / VBS scripting for advanced logic.
2. SIMATIC WinCC flexible 2008 Advanced / SP5 – the engineering tool that generated WinCC flexible Runtime; the Advanced edition permitted the runtime to be installed on a PC instead of a Panel.
3. SIMATIC WinCC Unified PC (V17 / V18 / V19 / V20) – the modern, container-isolated, web-based runtime configured from TIA Portal, exposing OPC UA server, OPC UA client, GraphQL, and REST endpoints natively.

A fourth option, ProTool/Pro RT, is end-of-life but still encountered in brownfield installations; it is briefly covered for migration context. The engineering workflow for each product line is fundamentally different: WinCC V7 uses its own Explorer-based configurator, WinCC flexible Advanced uses the legacy flexible engineering tool, and WinCC Unified uses the shared TIA Portal engineering framework. This article compares the three PC-capable editions so that a system integrator can choose the correct runtime based on PLC family, tag count, IT/OT integration requirements, lifecycle, and licensing budget.

2. WinCC V7 / V7.x – Classic SCADA for Plant PCs

WinCC V7 (formerly branded simply "WinCC" up to V6.2, then renamed "WinCC V7" from V7.0 onward) is the original Siemens PC SCADA. It installs on Windows 10/11 IoT Enterprise or Windows Server 2019/2022, depends on SQL Server for the runtime/archives database, and uses the proprietary CCAgent channel DLLs to communicate with SIMATIC S7-300/400, S7-1200/1500, SINUMERIK, and third-party PLCs.

2.1 Architectural Components

• WinCC Explorer – central project tree (Computer, Tag Management, Graphics Designer, Alarm Logging, Tag Logging, User Administrator, Cross Reference).
• Graphics Designer – vector and bitmap editor for process screens.
• Alarm Logging – event-driven message system with optional acoustic/visual acknowledgement.
• Tag Logging – cyclic and acyclic process-value archiving to SQL Server.
• Global Script (C / VBS) – runtime logic via ANSI C or VBScript projects.
• Channel DLL – SIMATIC S7 Protocol Suite, SIMATIC S5 Ethernet, OPC, Allen-Bradley DF1, Modbus TCP/IP, etc.

2.2 Performance Envelope

2.3 Licensing Model

WinCC V7 licenses are sold as RT (runtime) only; the engineering software is purchased separately. Base RT 128 covers 128 PowerTags, RT 256 covers 256, RT 512 / 1024 / 2048 / 4096 / 8192 / 16384 / 32768 follow, and beyond 32,768 a Powerpack upgrade is required. A WinCC/Redundancy option license, a WebNavigator option, a DataMonitor option, and a Process Historian license are all separate SKUs.

3. SIMATIC WinCC Unified PC – The Modern Runtime

WinCC Unified PC is the strategic PC runtime from TIA Portal V17 onward. It is configured inside the same TIA Portal project as the PLC, the safety PLC, the drives, and the Comfort/ Unified Panels, then deployed to a PC or virtual machine. Unlike V7, Unified does not depend on SQL Server; it stores project data in an SQLite-based archive and exposes data through a built-in OPC UA Server, OPC UA Client, GraphQL gateway, and RESTful API.

3.1 Supported Platforms

• Windows 10 / 11 Enterprise LTSC 2019 / 2021, Windows Server 2019 / 2022 (x64).
• Container-based deployments on Linux via SIMATIC Runtime Manager (experimental, TIA V20 onward).
• Hyper-V / VMware ESXi virtual machines with hardware-assisted virtualization enabled.

3.2 Runtime Limits (TIA V19 / V20)

3.3 OPC UA and GraphQL Surface

WinCC Unified PC exposes an OPC UA Server namespace at opc.tcp://<host>:4840 that auto-publishes all HMI tags, alarms, and historical archives. The same tag set is mirrored to a GraphQL endpoint at https://<host>:4002/graphql so that MES / BI / Python tooling can query without an OPC UA stack. Read-only access uses anonymous authentication in default install; write access requires a Unified user with the role HMI Administrator or HMI Operator.

4. WinCC flexible 2008 Advanced – Legacy PC Runtime

WinCC flexible 2008 (last SP5 update) introduced the Advanced edition that allowed the runtime to be installed on a PC. The PC runtime communicates with the PLC via SIMATIC HMI HTTP, MPI/DP, PROFINET, or OPC channels; the configuration project is built in WinCC flexible and downloaded to the PC as a compact runtime image (.fwc). WinCC flexible is fully superseded by TIA Portal WinCC (Comfort / Advanced / Professional) and the Unified line; Siemens officially de-listed new sales of WinCC flexible in 2017 and supports it only through legacy support contracts.

4.1 Why Engineers Still Encounter It

• S7-300/S7-400 sites that upgraded from ProTool to WinCC flexible 2005/2008 and never migrated.
• OEM machine builders whose end-customer has frozen the controller generation for spare-part commonality.
• Plants with an installed base of WinCC flexible Panels (TP177, MP277, MP377) that share an engineering project with a PC runtime.

4.2 Variable / Tag Limits (Advanced)

5. ProTool/Pro RT – Brownfield Context

ProTool/Pro (RT) is the DOS / Windows 9x era predecessor that allowed HMI screens to run on an industrial PC communicating with SIMATIC S5 and early S7-300 stations. Its configuration tool, ProTool CS, accepted the same project files later imported by ProTool V6.0 and WinCC flexible Converter. Today ProTool is unsupported; if a legacy ProTool RT PC must be retired, migrate by using the WinCC flexible Converter or, for newer TIA Portal environments, the WinCC Migration Tool (TIA V17 add-on).

6. Licensing Architecture Across the Three Runtimes

Siemens licenses all three PC runtimes by counting external tags (PowerTags / HMI tags / external variables) that point to the PLC plus any internal tags that participate in logging or alarming above the bundled allotment. License keys are managed by the Automation License Manager (ALM) and stored either locally on a USB dongle (rare today) or as a soft-key file bound to a System ID derived from the host's C: drive serial.

7. Hardware and Driver Requirements

All three runtimes require an industrial-grade PC (Siemens SIMATIC IPC227G / IPC277G / IPC477E / IPC647E / IPC847E or equivalent) with a vendor-supported chipset. Consumer motherboards are not approved because the ALM System ID is derived from the disk serial and BIOS UUID, both of which can shift after a BIOS flash on consumer boards, voiding the license.

7.1 Minimum Verified Platforms (Siemens Approved)

7.2 Driver / Interface Stack

• PROFINET – Intel I210 / I350 NIC or Siemens CP 1616 / CP 1626 PCIe card with shipped NDIS driver.
• MPI / PROFIBUS – Siemens CP 5611 / CP 5612 / CP 5711 PCIe or USB adapter; requires COM port emulation service S7EHRSCAN running.
• OPC – either the built-in OPC DA server (WinCC V7) or an external Kepware / Matrikon tunnel.
• Modbus TCP / EtherNet/IP – third-party channel (WinCC V7 Channel "Modbus TCP/IP" or WinCC Unified "Third-party / Modbus" driver).

8. Communication Protocols and Stack Details

The most common path is S7-1200 / S7-1500 over PROFINET, configured by inserting the PLC as a partner in the WinCC project and selecting SIMATIC S7-1200, S7-1500 channel (WinCC V7) or HMI Connection > S7-1500 (WinCC Unified).

8.1 S7 PUT/GET vs Optimized Block Access

WinCC V7 still relies on legacy PUT/GET (DB-any read) unless the Optimized block access option of the S7-1500 is disabled; WinCC Unified reads both, but the optimized access model must be enabled and the DB made non-not-accessible-from-HMI by clearing the "Accessible from HMI / OPC UA" attribute on the relevant DBs.

8.2 OPC UA Mapping (WinCC Unified)

// Example: OPC UA node structure exposed by Unified PC
opc.tcp://192.168.10.50:4840
  └─ ns=3;s=Plant1\LineA\Booster\Pressure   // Float, 100 ms, writable
  └─ ns=3;s=Plant1\LineA\Booster\Run         // Boolean, 50 ms, read-only
  └─ ns=3;s=Alarms\Active\_Acknowledge       // Method, callable

8.3 GraphQL Query Example

query TrendQuery {
  currentValues(tags: ["Plant1/LineA/Booster/Pressure",
                       "Plant1/LineA/Booster/Temperature"]) {
    tag
    value
    timestamp
    quality
  }
}

The endpoint https://<host>:4002/graphql accepts the same JSON body via POST. Authentication is a Bearer token issued by the Unified Configuration Console under User Management > API Roles.

9. Selection Matrix

9.1 Recommendation Heuristics

• Brownfield S7-300/400 with < 4k tags and no IT integration → keep WinCC flexible Advanced or migrate to WinCC V7 with the SIMATIC S7-300/400 Channel.
• Greenfield S7-1500 with OPC UA integration, multi-vendor PLCs, or MES / BI consumption → WinCC Unified PC.
• Large plant with 10k+ tags, multi-server redundancy, historian, multi-client visualization → WinCC V7 with WinCC/Redundancy and Process Historian.

10. Configuration Walk-Through: TIA Portal WinCC Advanced as PC Runtime

The most common 2024-era scenario is a PC that runs a WinCC Advanced Runtime built from a TIA Portal project that also contains an S7-1200 / S7-1500 PLC.

10.1 Prerequisites

• TIA Portal V17 / V18 / V19 installed with WinCC Advanced / Professional option.
• WinCC Runtime Advanced license installed via ALM.
• Same Windows user account on engineering PC and target PC, member of SIMATIC HMI local group.
• PROFINET or Ethernet IP route between PC and PLC (verify with ping).

10.2 Step-by-Step

1. In TIA Portal, right-click the project and choose Add new device > SIMATIC PC station > WinCC Runtime Advanced.
2. Drag an S7-1200 / S7-1500 station into the project, then create an HMI connection from the PC station to the PLC.
3. On the connection, set the PLC address (IP or PROFINET name) and the PLC slot / rack.
4. Add HMI tags and bind them to PLC DB / I / Q addresses; enable Acquire continuously with a 100 ms cycle for process values.
5. Build the runtime: right-click the PC station > Compile > Software (rebuild all). Resolve all warnings.
6. Transfer the runtime via Online > Download to target system > PC station. TIA Portal will deploy via the configured routing path; if direct routing is unavailable, export the .rtp runtime package and install it manually with RT Loader on the target PC.
7. On the target PC, run WinCC Runtime Loader, point it at the deployed project, and select Start Runtime on system startup.

10.3 Verification

• From the target PC, open Start > Programs > Siemens Automation > WinCC Runtime Advanced > Diagnostic. Confirm all tags show "Connected" and no red channel-error icons appear.
• Force a tag from the PLC and confirm the value appears in a connected tag view within two acquisition cycles.
• Trigger an alarm and confirm the Alarm Logging window turns red and the horn outputs the configured audio file.

11. Commissioning Checklist for WinCC Unified PC

1. Activate the Runtime Manager service Siemens.Simatic.RuntimeManager; it must be Automatic on boot.
2. Open the Unified Configuration Console, set the runtime to Start automatically, choose the deployed project, and click Start.
3. Verify the OPC UA endpoint with the OPC UA client UA Expert: browse the namespace tree, read a process tag, and write a boolean to confirm bidirectional flow.
4. Issue a GraphQL query from GraphQL Playground against https://<host>:4002/graphql and validate the JSON payload.
5. Open the WinCC Unified Client in a browser at https://<host>/unified on a remote engineering PC and verify both process and alarm screens render.
6. Apply Windows Firewall rules: allow inbound TCP 4002 (GraphQL), 4840 (OPC UA), 443 (Unified Client) from the corporate VLAN only.

12. Migration Paths

13. Common Field-Proven Caveats

• ALM System ID drift after disk clone: WinCC V7 will deactivate the license if the source and clone share a System ID; run Cofirmware key regeneration via the ALM portal or recreate the soft-key on the cloned hardware.
• S7-1500 optimized DBs invisible to V7: if the project is left at default settings the runtime shows "Variable not connected" for every tag; either disable optimized access for the affected DBs or upgrade to Unified.
• OPC UA certificate trust loop: Unified PC ships with a self-signed certificate; remote OPC UA clients reject it until the certificate is moved into the Trusted store on the client side or replaced with a CA-signed certificate via the Configuration Console.
• Firewall blocks OPC UA discovery: ports 4840 (server) and 4841 (discovery) must be open bidirectionally between HMI and any external OPC UA client.
• License upgrade path: WinCC V7 Powerpacks are additive – a 2048 → 4096 upgrade does not require a new base license; WinCC Unified upgrades are tier-jump – going from the 500-tag to 2,500-tag license is a single replacement SKU.

14. Frequently Asked Questions