WinCC Professional Licensing: Resolving Tag Count Exceeded

Overview

WinCC Professional in TIA Portal separates engineering licenses (ES) from runtime licenses (RT). A common field scenario is an engineer inheriting a multi-thousand-tag WinCC Professional project built in TIA V13 SP2 with only a 4096 power tag ES license available in TIA V17, and a need to engineer new screens, simulate the runtime, and rebuild the RT package for an on-site RT PC. This reference documents the license components required, the migration constraints triggered by tag count overflow, the path to local runtime simulation, and the cost-driven decisions between tag expansion and a multi-client RT bundle.

The underlying behavior is governed by the Siemens Automation License Manager (ALM), the WinCC Professional V17 license key model, and the TIA Portal V13 SP2 to V17 migration toolchain. The two URLs in the Additional Research section (Licensing STEP 7 and WinCC and Licensing (RT Professional)) are the canonical references for the license key model used in this article.

Problem Details: Tag Count Overflow and Missing RT Component

Two distinct license issues surface when an engineer attempts to take over a large WinCC Professional project:

1. Power tag overflow. The project was authored against a 19,000+ tag power tag license. The engineer's available license is a WinCC Professional V17 with 4096 power tags. The engineering client will open the migrated project, but TIA Portal will flag the project as exceeding the licensed tag count during the migration step and will block the compile/download for runtime.
2. Missing RT Professional component. WinCC Professional (the ES package) only authorizes engineering. To simulate the runtime locally on the engineering PC or to generate a loadable RT image for an on-site RT PC, an additional WinCC RT Professional license is required on the same machine. Without the RT license, the simulation launches but tag connections report unhealthy and alarms/trends do not update.

Root Cause: License Key Mismatch vs. Feature Mismatch

The two symptoms have different root causes and require different remediations:

Per the official Siemens documentation at Licensing STEP 7 and WinCC, every WinCC component on a given PC must have a corresponding valid license key in the Automation License Manager. The ES package (WinCC Professional) is independent from the RT package (WinCC RT Professional); they are licensed and counted separately.

License Model: ES Professional vs. RT Professional

The RT Professional license packages per the official WinCC documentation (Licensing (RT Professional)) are available with 1, 3, 10, 30, and 100 clients. Client count refers to the maximum number of concurrent operator stations (WinCC Viewer, WebNavigator, or thin clients) that can attach to the RT server at one time.

Migration Path: TIA V13 SP2 → V17

The migration sequence must be planned because the license audit happens at compile:

1. Install TIA Portal V17 with WinCC Professional on the engineering PC.
2. Open Automation License Manager and confirm the V17 4096 power tag key is on the local license container (or a network license server reachable from the PC).
3. Open the V13 SP2 project in TIA V17. The portal will run the migration wizard. Expect the project to migrate; the tag-count warning appears at this point but does not block opening.
4. Edit freely. Adding screens, HMI tags, alarms, and trends is allowed even if the cumulative tag count exceeds the license; TIA Portal will not prevent the edit.
5. At compile, the portal reports the tag count delta and refuses to generate the RT image until either (a) the licensed tag count is raised, or (b) the active power tag count in the project is reduced.

Resolution: Three Valid Options

Option A — Order an Expanded ES + RT License

Order a WinCC Professional V17 license with sufficient power tag count (e.g., 32768 or 65536) to cover the 19,000+ tag project plus headroom, and a matching WinCC RT Professional license with a client count sized to the on-site topology. This is the cleanest path but, as the source indicates, the price delta between 4096 and the higher tiers can be in the order of several thousand to ten-thousand euros/USD, depending on region and distributor.

Option B — Reduce Active Power Tag Count

Audit the project for unused HMI tags, orphaned DB references from the S7-1500/S7-300 side, and historical tags left over from prior revisions. Use the "Cross-references" tool in TIA Portal and the WinCC tag statistics export to identify candidates for removal. If the live tag count can be brought below 4096, the existing ES license is sufficient. This is rarely practical for a 19,000-tag project because most of those tags are typically live.

Option C — Split the Project (Multi-HMI Topology)

For very large plants, the SCADA layer is often split: an ES license stays at the original tier, and the project is partitioned so each Runtime Professional instance handles a tag subset. This requires WinCC Server licensing on top of the base RT Professional. This option is structural, not a workaround, and is documented in the RT Professional manual.

Enabling Local RT Simulation on the Engineering PC

To simulate the WinCC Professional runtime locally, the engineering PC must host a WinCC RT Professional installation with a valid license key. The launch sequence is:

1. From the WinCC Professional project tree, right-click the HMI device → "Start Runtime".
2. The WinCC Runtime Professional launcher invokes the local RT service. If the RT license key is absent, the launcher fails and reports a license error in the dialog.
3. With a valid RT Professional key, the runtime starts, opens the start screen, and tag connections become healthy once the S7-1500/S7-300 PLC is reachable on the configured subnet.

If tags still report bad quality after the RT license is verified, the issue is connectivity, not licensing. Validate with the following checks:

• PLC is online and the protection level on the S7 CPU matches the configured HMI connection password.
• The HMI connection's S7 subnet is bound to a network adapter that is up (TIA Portal → Devices & Networks → Subnet properties).
• PG/PC interface on the engineering PC is set to the correct Ethernet adapter (Set PG/PC Interface, S7ONLINE → TCP/IP).
• No firewall rule blocks port 102 (S7 communication) between the engineering PC and the PLC.

Generating the RT File for the On-Site PC

The compiled WinCC Professional project is packaged as an RT image for transfer to the on-site Runtime PC. Procedure:

1. In TIA Portal, select the HMI device (PC station running WinCC RT Professional).
2. Compile → Software (rebuild all). Confirm no errors.
3. On the project tree, select the HMI device → "Load to file system". Choose a target path on the engineering PC.
4. The output is a complete RT image including the runtime database, alarm logs, and script files. Copy this folder to the on-site PC.
5. On the on-site PC, run the generated loader executable. The on-site PC must have a WinCC RT Professional license with a client count that matches the deployed operator station count.

OPC Server Licensing on RT Professional

If the WinCC Professional project exposes data to third-party systems via OPC UA or OPC DA, the on-site RT PC requires the WinCC Runtime Professional license plus the WinCC OPC server option. Per the official documentation at Licensing (RT Professional) — OPC, the OPC server option is a separate license key on top of the base RT Professional license. Without this option, the OPC server service will not start and external OPC clients will receive no data.

Automation License Manager Workflow

All WinCC and STEP 7 Professional license keys are managed through the Siemens Automation License Manager (ALM), which is installed alongside TIA Portal. Practical procedures:

1. Open ALM from the Windows Start menu (Siemens Automation → Automation License Manager).
2. The left pane lists available license containers: local drive, USB stick, or network license server.
3. To move a key: right-click the key → "Transfer". Confirm the destination container.
4. To return a key: right-click the key → "Return". This frees the key to be re-assigned to another PC.
5. For network licensing, the engineering PC points to the license server via "Connect to License Server" in ALM. The server must be reachable on TCP port 4410.

Detailed step-by-step procedures are documented at Licensing STEP 7 and WinCC.

Troubleshooting Matrix

Verification Checklist

After applying the chosen resolution, verify the configuration end-to-end:

1. ALM shows the V17 WinCC Professional key (ES) and the V17 WinCC RT Professional key (RT) on the correct PCs.
2. TIA Portal opens the migrated V17 project without license warnings other than the tag count audit.
3. Compile → Software (rebuild all) completes with no errors.
4. Right-click the HMI device → "Start Runtime". The WinCC Runtime Professional launches and the start screen appears.
5. All configured HMI tags show "Good" quality in the tag diagnostics (online → tag simulation → status).
6. Alarms can be acknowledged, trends update, and scripts execute.
7. "Load to file system" generates a complete RT image folder; copy to on-site PC and verify it loads.
8. On-site RT PC runs the project with healthy tag connections; all configured clients connect up to the licensed client count.

Cost-Driven Decision Path

The decision between upgrading the ES license tier and splitting the project depends on the following field-calibrated tradeoffs:

• If the project is expected to grow (more tags per revision), the higher ES license tier amortizes over time.
• If the project is being retired or handed off, a single non-recurring engineering purchase is cheaper than restructuring the topology.
• Multi-client RT bundles (10/30/100) are economically favorable when the on-site SCADA already has many operator stations.
• Splitting into a WinCC Server topology adds WinCC Server + WinCC Client licensing; it is justified only at the largest scales.