PCS 7 V7.1 Motor Block Icon Not Flashing on MSS Trip Feedback

1. Problem Overview

On a Siemens SIMATIC PCS 7 V7.1 station, an operator notices that the runtime graphic of a standard library motor driver block does not flash red/yellow when the motor starter reports a trip via the MSS input. Instead, the block icon simply stops the animation and locks the symbol in a static "stopped" or "faulted" state without the configured flashing cadence that the operator expects. The fault is purely cosmetic at the HMI layer: the CFC logic still shuts the motor down correctly via the trip path, but the visual feedback that would normally attract the operator's attention on the overview area is missing.

This is a recurring issue in PCS 7 V7.1 because the standard motor block icon shipped in @PCS7 Typical.pdl was designed to flash on a defined set of quality codes, not on the MSS (Motor Starter Status / starter feedback) bit directly. If the MSS feedback is wired to a status input that the default icon does not evaluate for flashing, the icon will never enter the flashing state regardless of how the CFC program evaluates the trip.

2. Root Cause Analysis

The motor block icon flashing is governed by three layers:

1. CFC layer — the MOT_… / MOTOR / MOT_SPEED block receives the trip feedback at its MSS input and routes it to the block's status word.
2. OS compilation layer — OS Project Editor generates WinCC tags from the CFC chart and writes them into the OS server's tag database.
3. Graphics layer — the block icon in @PCS7 Typical.pdl evaluates specific status bits via an Extended Status Display or Status Display object. The icon's version number (the trailing /1, /2, /3, … suffix on the block name) determines which attribute is bound to which flash color.

If the icon version visible on the OS was linked through a path that does not bind the MSS bit to a flashing attribute, the runtime graphic cannot flash — even though the tag is changing correctly in WinCC Tag Management. Typical triggers for this condition:

• The block icon was copied from a project-specific Typicals.pdl that was created before MSS flashing was added to the standard icon.
• The block icon was inserted manually into a picture instead of being placed via the SFC/CFC chart's OS Picture assignment, breaking the Prototype link.
• A customized icon was created without copying the latest icon version number, leaving the link to the outdated structure.
• The MSS feedback was wired to a non-standard input name (e.g., FAULT, TRIP) rather than the expected MSS connector.

3. Block Icon Architecture in PCS 7 V7.1

The PCS 7 standard library motor blocks expose a status word that is consumed by WinCC through an internal tag structure. The block icon in @PCS7 Typical.pdl uses Siemens's proprietary Extended Status Display object to map each status code to a visual: color, shape, and flash frequency.

The flashing cadence is controlled by the WinCC property "Flashing color change" on the Status Display object. Two flash colors can be assigned per object: a base color and an alternate color. The runtime swaps between them at the configured period (default 500 ms / 500 ms in PCS 7 V7.1 standard).

4. Pre-Diagnostic Procedure

Before changing graphics, verify the data flow from CFC to the HMI tag. This rules out a CFC, compilation, or tag-link problem before touching WinCC.

1. Open the CFC chart containing the motor block and confirm that the MSS input is physically connected to the trip-feedback signal from the starter. The connection must be a named pin-to-pin wire, not an implicit signal.
2. Check the block's online view (right-click → Watch On or Open in CFC Online) and confirm that the MSS input actually goes to 1 when the trip occurs.
3. Run OS Project Editor on the S7 program → Compile OS. Verify that no warnings about missing tags or unmatched structure types are reported.
4. On the OS server, open WinCC Explorer → Tag Management and locate the structure tag corresponding to the motor block. Confirm that the MSS sub-tag is present and toggles correctly when forced.
5. Open the runtime picture, place a diagnostics IO field bound to the same MSS tag and verify it tracks the input.

If the IO field tracks correctly but the icon does not flash, the issue is in the graphics layer — proceed to Section 5.

5. Solution A — Verify or Refresh the Default Block Icon Link

The fastest fix is to re-link the existing icon to the motor block's status structure using the Dynamic Wizard.

1. In WinCC Graphics Designer, open the picture containing the affected motor block icon.
2. Right-click the icon and select Dynamic Wizard → Standard Dynamics.
3. Choose "Link Prototype to a Structure".
4. In the wizard, browse the WinCC tag structure and select the motor block's status structure (typically named after the CFC chart block, e.g., MOTOR_001.STATUS or <chart>/<block instance>).
5. Confirm the link. The wizard rewrites the icon's tag bindings to point at the new structure.
6. Recompile and save the picture. Restart WinCC Runtime.

If the link was already correct, the Dynamic Wizard will report "no change" and the problem lies elsewhere.

6. Solution B — Replace the Icon with the Default from @PCS7 Typical.pdl

When the picture contains a non-standard or user-modified icon, replace it with the canonical version that PCS 7 shipped with the master data library.

1. In WinCC Graphics Designer, open @PCS7 Typical.pdl from the project's GraCS directory.
2. Locate the standard motor block icon (search for the prefix @ + motor block type, e.g., @MOT_…).
3. Copy the icon and paste it into the target picture at the same coordinates.
4. Use Dynamic Wizard → Standard Dynamics → Link Prototype to a Structure to bind the new icon to the motor's status structure as described in Section 5.
5. Delete the old, non-flashing icon.
6. Save the picture and recompile the OS.

7. Solution C — Create a Custom Block Icon with a New Version Number

If the default icon's flashing attribute is wired to a different bit than the one your project uses for trip feedback, create a project-specific variant with a higher icon version number.

1. Open @PCS7 Typical.pdl and select the motor block icon you want to copy.
2. Copy the icon to a working area in the same picture or to a new Typicals.pdl.
3. Open the icon's Object Properties and rename it by appending a version suffix: @MOT_…/4 (the next free version number). The version number is what tells WinCC which icon variant to instantiate when the CFC block is placed on a picture.
4. Open the icon's Status Display child object and edit the flashing property:
   • Flashing on: bind to the binary tag that goes true when MSS trips. Use the tag picker and select the MSS sub-tag of the motor structure.
   • Base color: the "current" color of the fault state (typically red).
   • Flash color: the alternate color shown during the flash (typically yellow, per PCS 7 standard).
   • Flash period: 500 ms / 500 ms is the PCS 7 default. Adjust to taste in the range 250 ms – 1000 ms.
5. Save the modified Typicals.pdl.
6. Insert the new icon in the target picture and link it to the motor's status structure using the Dynamic Wizard (Section 5).
7. Re-run OS Project Editor → Compile OS so that the new icon variant is registered as the default for blocks referencing the higher version number.

8. Solution D — Manual Flash Binding via Object Properties

If you do not want to create a new icon variant, you can bind the flashing attribute directly on any existing icon instance.

1. Open the picture in WinCC Graphics Designer and select the motor block icon.
2. Open Object Properties → Properties → Static (or Miscellaneous, depending on WinCC build).
3. Locate the Flashing property group.
4. Create a direct tag link on the FlashColorActive or FlashColorOn attribute and bind it to a binary tag that mirrors the MSS feedback. A small CFC auxiliary block or a WinCC script can be used to derive the binary tag.
5. Define the two flash colors and the flash period.
6. Save, recompile, and test in Runtime.

This approach is quick but is applied per icon instance. For fleets of motor blocks, prefer Solution C (centrally managed icon in Typicals.pdl).

9. Configuring Custom Flash Colors

The default PCS 7 flash pairing is red ↔ yellow for faults. To change the colors project-wide:

1. Open the block icon in @PCS7 Typical.pdl or your project Typicals.pdl.
2. Select the inner Status Display object.
3. Open the FlashColors property. There are two color slots: Base and Alternate.
4. Enter custom RGB values or pick from the WinCC color palette.
5. Repeat for every flash-bearing icon (motor, valve, PID, etc.). Using a project Typicals.pdl keeps the change in one place.

10. Verification Procedure

1. Save and close all open pictures in Graphics Designer.
2. In WinCC Explorer, run OS Project Editor → Compile OS. Confirm zero errors and zero warnings.
3. Activate WinCC Runtime.
4. From the diagnostic test point, force the MSS tag to 1 in WinCC Tag Simulation or via the PLC (using Watch Table in STEP 7).
5. Observe the icon: it must transition from its current state to the configured flash pattern within one OS picture update cycle (typically 1–2 seconds with the standard 1 s/2 s OS refresh).
6. Force MSS back to 0; the icon must return to its non-flashing state within one cycle.
7. Test other motor blocks that use the same icon variant to confirm the change is consistent.
8. Repeat the test from a separate OS client to verify server-to-client tag replication.

11. Troubleshooting Matrix

12. Related Engineering Notes

• OS Project Editor is the only sanctioned way to register a new icon version; manual insertion of icons into pictures works but bypasses the standard version-management system. For projects with hundreds of motor blocks, always rely on the Project Editor.
• Cross-Reference in WinCC Explorer lists every picture in which a block icon is referenced. Use it to confirm that your icon variant replacement did not leave stranded references in unopened pictures.
• Picture-level vs. central typicals: a change to @PCS7 Typical.pdl affects every OS picture that instantiates that icon; a change to a project-specific Typicals.pdl affects only pictures in that OS project.
• Fallback during commissioning: if a flash attribute must be patched quickly during a hot commissioning phase, use Solution D (per-instance binding). Promote it to a project typical afterward for cleanliness.
• Upgrade safety: before upgrading from PCS 7 V7.1 to V8.x or V9.x, audit all custom block icons and version numbers. The Advanced Process Library in newer releases re-binds flash attributes to Quality / Status1 / Status2, which can silently break flash behavior on upgrade.