Resolving S7-1500 Motion Control Under-License Faults on GEAR/POS

Problem Details

An S7-1500 CPU (or ET 200SP CPU) running TIA Portal motion control reports an Under-license diagnostic fault on a technology axis that is configured for GEAR operation, even when a valid CAM runtime license is loaded on the CPU. The behavior typically appears in the following configuration pattern:

• Two technology axes are configured (e.g., a positioning axis plus a gearing/slave axis).
• A positioning license (6ES7xxx-0CC0x-0YA0-style entry) is installed for the first axis.
• A CAM license is installed on the CPU for the second axis.
• The catalog documents clearly state that the CAM license includes POS (positioning) and GEAR rights.
• Despite the inclusion list, the CPU raises fault code W#16#0000 / F-Code 135-style licensing diagnostic and the online License Dialog shows: POS: yes, CAM: yes, GEAR: no.

The fault prevents the gearing command from being released by the MC_Power/ MC_GearIn blocks and the technology object enters the Error state. A second, separate, valid GEAR license cannot be activated to clear the fault if the catalog already states the CAM license should include GEAR.

Root Cause

The Siemens motion-control license model on S7-1500 / ET 200SP CPUs is not a pure rights-inheritance hierarchy. While the marketing catalog and the TIA Portal License overview page document that the CAM license includes GEAR and POS, the runtime license check in the technology objects does not infer GEAR rights purely from the presence of a CAM license. The license state is keyed off of which technology objects have at least one cam configured and compiled, even if that cam is a placeholder or unused.

More precisely:

1. The CPU evaluates licensing per technology object (TO), not per license token.
2. For a TO configured as a positioning axis or synchronizing axis (gear), the runtime check looks for a matching active license on that TO.
3. The CAM license token is associated with technology objects that contain at least one cam definition (interpolated cam, cam disc, switching cam, or measurement cam). It is not auto-applied to a pure gearing TO.
4. When no cam TO exists in the project, the license dialog correctly reports GEAR: no and the gearing TO raises an under-license fault at first MC_GearIn call.

This is a known diagnostic quirk: the license appears valid at the CPU-wide license overview level, but the per-axis license state required by the technology object is missing. The catalog wording is technically correct (a CAM license entitles you to use GEAR) but does not describe the implementation detail that a cam TO must be present in the project for the license to be allocated to a gearing TO.

Affected Versions and Products

Some Siemens entry-level CPUs (CPU 1510SP, CPU 1511, CPU 1512C) bundle motion control licensing differently; on these, fewer features may be active by default. Always check the specific CPU's Siemens Industry Online Support entry for the bundle license list.

License Hierarchy Reference

The following table summarizes the documented license inclusion model for S7-1500 motion control. This is the catalog view; see the next section for the runtime reality.

Catalog inclusion means you do not have to buy a separate POS license if you have a CAM license. It does not mean the POS/GEAR rights are auto-attached to a TO that has no associated cam definition.

Diagnostic Procedure

Follow this sequence to confirm the fault and isolate it from other motion-control issues:

1. Go online with TIA Portal to the target CPU. Expand Online & diagnostics → Diagnostics → Motion Control diagnostics.
2. Open the License dialog under Online & diagnostics → Licensing or via the CPU's Properties → License overview. Note the per-license status indicators:
   • POS: yes
   • GEAR: no
   • CAM: yes
3. Open Project tree → Technology objects → [Axis_x] and inspect the Configuration → Type of axis field. Note whether the axis is configured as Positioning axis or Synchronous axis (gear).
4. Open the Diagnostics buffer on the CPU. Look for an entry of class Motion Control with a license-related ID (often a textual "License missing for technology object" or similar wording depending on firmware version).
5. Right-click the affected axis → Start drive & check axis. Confirm the under-license fault reappears on the first MC_GearIn attempt.

Solution

The verified field solution does not require an additional GEAR license purchase. Instead, you must ensure the runtime license checker can attach the CAM license token to the affected axis. There are two reliable approaches:

Option A — Add a Cam Technology Object (Preferred)

1. In the TIA Portal project tree, right-click Technology objects → Add new object.
2. Select Cam (or Cam_10, Cam_100 depending on the point count you need). Click OK.
3. Bind the cam TO to the gearing axis (its leading or following axis depending on the topology).
4. Compile the project. Do not delete this cam TO even if you do not actually use it in the program — it is required for license allocation.
5. Download the project (hardware configuration + software) to the CPU.
6. Go online and re-open the License dialog. The status should now read:
   • POS: yes
   • GEAR: yes
   • CAM: yes
7. Run the gearing program. The under-license fault clears and MC_GearIn engages.

Option B — Purchase a Standalone GEAR License

If your project policy prohibits a cam TO in the configuration, or if you have multiple gearing axes that each require their own license token, purchase the separate GEAR license (order number 6ES7822-0AE0x-0YA0 or the current equivalent). Load it onto the SIMATIC Memory Card using the Automation License Manager or the SIMATIC Automation Tool, then re-check the License dialog.

Option C — Verify the Existing CAM License Was Not Corrupted

Less common, but possible: an incomplete license transfer can leave the license token marked valid at the CPU level yet malformed at the technology-object level. In that case:

1. Remove the existing CAM license with the Automation License Manager.
2. Re-transfer the license from the certificate of license to the SD card.
3. Insert the SD card and power-cycle the CPU.
4. Recompile and download the project.

Verification

After applying Option A, perform the following checks before returning the machine to production:

1. License dialog confirmation: Online → License overview shows GEAR: yes.
2. MC_Power: Drive enables without a licensing fault and the axis state moves from Disabled to Standstill to Synchronizing.
3. MC_GearIn: The block returns Done with Busy = FALSE after the slave axis reaches synchronous velocity. The synchronization tolerance window is satisfied.
4. Diagnostics buffer: No further motion-control license entries appear during a 10-minute operational soak test.
5. CPU Webserver: If enabled, navigate to Diagnostics → Motion → License and confirm the displayed license states match the License dialog.
6. Recipe / cam parameters: If you added a placeholder cam TO, confirm it is not accidentally triggered in any OB (OB1, OB35, OB82, etc.). The placeholder must not generate cycle-time warnings.

Why the Catalog Statement Is Misleading

The Siemens motion-control catalog describes license entitlement — what you are allowed to do under a given license token. It does not describe how the TIA Portal runtime performs the license-to-TO binding. The binding requires the existence of a TO whose type matches the license grant. For CAM, the matching TO is a cam object. The catalog's "includes GEAR" wording is a legal statement: you are entitled to run gear applications. It is not a technical statement: the CAM token will not auto-bind to a TO with no cam definition.

This is a documentation/runtime mismatch that has surfaced in community-tracked TIA Portal issues for multiple firmware generations. The runtime behavior has not been changed as of the current firmware releases, presumably because it is classified as "working as implemented" rather than as a defect.

Related Issues and Edge Cases

Best Practices for S7-1500 Motion Licensing

1. Always add a cam TO for every CAM-licensed project, even if you plan to use only gear functionality initially. This avoids the under-license fault if the application pivots to camming later.
2. Document license allocations in the project header. Create a simple table mapping each technology object to the license token it consumes.
3. Store the Automation License Manager backup (.zip) of all motion licenses in a versioned project subfolder, with a checksum file.
4. Test license behavior in the TIA Portal simulation (PLCSIM) before commissioning hardware. PLCSIM honors license states in the same way as a physical CPU for most motion-control versions.
5. Lock the SD card write-protect switch after all licenses are written, to prevent accidental overwrite during runtime license checks.
6. Cross-check the License dialog on every firmware upgrade. Behavior is stable, but the diagnostic text and ID numbers can change between firmware versions.

Hardware and License Tool Reference

Safety Considerations

Motion control faults on a running machine can leave axes in undefined states. Before applying any of the workarounds in this article, ensure:

• The machine is in a safe state (drives de-energized or in Safe Stop).
• Safety functions (PROFIsafe, F-CPU) are not bypassed.
• The project is archived before any license or technology-object changes.
• Stop-categories and E-stop circuits are verified per IEC 60204-1 and ISO 13849-1.

FAQ