Resolving PCS 7 V9.0 SP2 APL Operator Trend Control Save Failure

1. Problem Summary

In PCS 7 V9.0 SP2 with the optional CEMAT V9.0 SP2 library installed, the APL Operator Trend Control (block type @APL_OperatorTrendControl, also referenced as AOTC) refuses to save a newly created trend group during runtime. The operator opens the trend view from the operator picture, drags one or more process tags into the trend window, assigns a trend group name, and the OK button in the Save dialog either remains permanently disabled (grayed out) or responds to mouse clicks without committing the change. The trend group therefore never appears in the trend archive selection, and the operator cannot recall it after a station restart. The failure is not produced by a WinCC dialog error, an S7 CFC compile fault, or a Step7 ES log entry — the dialog silently rejects the input.

This document covers the two independent root causes observed on customer systems, the diagnostic procedure to distinguish between them, and the concrete corrections available inside WinCC User Administrator and the AOTC runtime faceplate.

2. Affected Software Versions

References used:

• APL Operator Guide V9.0 (PDF)
• APL Operator Guide V9.1 (PDF)

3. Root Cause Analysis

Two distinct, non-mutually-exclusive root causes have been reproduced in the field. Either one is sufficient to make the OK button inactive.

3.1 Root Cause A — Missing or Insufficient Area Permission

The AOTC Save action runs through the same WinCC authorization layer that protects operator inputs. Per APL Operator Guide V9.0 §12.1, page 418, the operator user account must hold the area authorization for every tag currently selected in the trend group. If even a single tag in the trend belongs to an OS area that the logged-in operator does not have rights on, the Save dialog refuses to enable OK. The behavior is identical to a tag that has been configured read-only for the operator (red cross icon in the AOTC). Because the trend control does not display a separate error message in this case, the failure presents only as a permanently grayed OK button.

The classic trap occurs when an APL block icon was copied from one SFC/CFC chart into another graphic without re-binding the OS area reference. The block icon visually looks correct, but its s7_area attribute still points at the source hierarchy. A user that only has rights on the destination hierarchy cannot save a trend that contains the orphaned tag.

3.2 Root Cause B — Trend Group Name Not Committed to the Text Field

The trend group name edit field is bound to a WinCC internal variable. Until the operator presses Enter (or tabs out of the field) the variable is not written, and the AOTC Save command handler evaluates the field as empty. With an empty name the dialog disables OK by design — the trend group would otherwise be created nameless and immediately clash with subsequent attempts.

This root cause is by far the more common one on first-time deployments and is corrected purely at the operator station; no engineering change is required.

4. Symptoms and Field Signatures

5. Diagnostic Procedure

1. Log on to the OS with the operator account that is failing — not with the engineer account, since engineers usually have unrestricted OS areas.
2. Open the affected operator picture and launch the AOTC faceplate.
3. Attempt to save the trend group with a known-good name such as TEST_GRP_001.
4. If OK remains disabled, click into the trend group name text field and press Enter on the keyboard. Do not click the field again — just press Enter once.
5. If OK becomes enabled after the Enter key, Root Cause B is confirmed. Skip to §7.2 for resolution.
6. If OK still remains disabled, Root Cause A is the active cause. Continue with step 7.
7. Open WinCC Explorer → User Administrator. Locate the operator's group, open the Authorizations tab and the Area tab side by side.
8. For every tag currently in the trend, expand the S7 program and identify the Area each tag's block icon is configured against (right-click the block icon → Object Properties → Miscellaneous → Area).
9. If any tag references an area not listed in the operator's Area Rights, that tag is the blocker.

6. Pre-Remediation Checklist

• Confirm the OS server has been recompiled and downloaded after any S7 program change. Stale trend tag references behave like orphan area references.
• Verify the operator is not running in SIMATIC Logon with a fallback user. Open SIMATIC Logon → Configuration on the OS and confirm the active Windows user matches the user logged in inside the WinCC logon dialog.
• Check the WinCC project version. Mixed ES / OS version (e.g. V9.0 SP2 ES, V9.1 OS) can silently disable certain operator functions.
• Confirm the AOTC block instance exists in the S7 program and the CFC chart has been downloaded to the AS. If the AS connection is broken, the trend control runs in degraded mode and disables Save.

7. Solution A — Area Permission Correction

7.1 Grant the Operator the Missing Area

1. Open the OS project in the engineering station.
2. Launch WinCC Explorer → User Administrator.
3. Select the operator group (for example OPERATOR_CEMENT) and switch to the Area tab.
4. For every OS area where an orphaned tag was identified, enable the checkbox next to that area. The text is exactly the OS area identifier configured on the block icon.
5. Compile the OS. Either right-click the OS server and choose Compile → All (with tag export), or use the menu OS → Compile OS.
6. Download the runtime to the affected OS server. A hot reload is not sufficient for User Administrator changes — a full Download to Target System is required so the encrypted authorization file is refreshed.
7. Re-test the AOTC Save action from the operator station.

7.2 Re-bind the Block Icon to the Correct Area

If granting the area is undesirable for security reasons, fix the block icon instead:

1. Open the affected CFC chart in PCS 7 ES.
2. Select the block whose icon was copied from a foreign hierarchy. Open Object Properties → Connections and verify the S7_area attribute points to the correct hierarchy.
3. If the attribute is wrong, change it to the hierarchy the block actually belongs to, recompile the OS, and download.
4. Verify in WinCC that the tag now resolves to the expected area (WinCC tag management → tag properties → S7 area).

7.3 Reduce the Trend Tag Set to Authorized Tags

If the operator is correctly scoped and the trend must stay restricted, remove the unauthorized tag from the trend group rather than granting wider rights. The Save action requires 100% of the in-trend tags to be authorized, not a majority.

8. Solution B — Commit the Trend Group Name

The user-side correction for Root Cause B is a single key press. Once the operator understands the input model, the issue does not return.

1. Open the AOTC Save dialog.
2. Type the trend group name in the text field, for example MILL_03_TEMP_TREND.
3. Press Enter on the alphanumeric section of the keyboard. The numpad Enter also works but is less discoverable.
4. Confirm the OK button is now enabled (no longer grayed).
5. Click OK to commit the trend group.

8.1 Permanent Fix via Operator Training Procedure

Update the operator documentation (typically the CEMAT Operator Handbook or the PCS 7 OS Operator Manual). Add the following instruction:

To save a new trend group: (1) select the tags, (2) type the group name, (3) press Enter, (4) click OK.

9. WinCC User Administrator Reference

10. Verification Procedure

After applying either Solution A or Solution B, verify the fix using the steps below. Each must succeed before the ticket is closed.

1. From the operator station, log on as the same failing operator user. Log off any engineer accounts first to avoid permissions bleed.
2. Open the operator picture containing the AOTC faceplate.
3. Add at least three different process tags to the trend view. Mix tag types if possible (analog input, motor speed, valve position) so that any single-area failure is exposed.
4. Type a unique trend group name (use timestamp suffix to avoid collisions).
5. Press Enter.
6. Confirm the OK button is active (not grayed).
7. Click OK.
8. Close the AOTC faceplate and reopen it. Confirm the new trend group appears in the saved-group selection list.
9. Restart the OS Runtime (or simulate a station restart if the OS is the redundant pair). Confirm the trend group is still listed.
10. From a different OS client (redundant server), confirm the trend group is replicated. If it is missing on the standby, repeat the OS download on that server.

11. Related Configuration Pitfalls

11.1 AOTC Block Not Compiled Into the OS

If the AOTC faceplate is visible but the Save dialog never opens, the block icon was placed on the picture but the underlying WinCC picture function AOTC_Save.pdl is missing from the project's Pictures folder. Compile the OS with the option Include all pictures to recover.

11.2 Trend Tags Removed From the S7 Program

If the Save action completes but the trend shows "no data" after a hot restart, the underlying CFC block was deleted but the OS tag list still contains stale references. Recompile the OS with Scope = Entire OS, not the delta scope, to force a tag cleanup.

11.3 User Administrator File Not Synchronised

After editing User Administrator on the ES, both the project file and the runtime file on the OS server must match. Use OS Project Editor → Download → User Administrator as a discrete step, separate from the bulk OS download. Many field engineers miss this step and end up granting rights on the ES but not on the runtime.

11.4 CEMAT-Specific Authorization Layer

CEMAT V9.0 SP2 wraps APL operator blocks with an additional CEMAT Authorizations layer (authorization numbers 1000–1099). Verify the operator has the CEMAT_TREND_SAVE bit enabled. CEMAT operators without this bit see a grayed OK identical to the APL symptom, but the fix is in the CEMAT permission matrix, not the APL area list.

12. Prevention and Best Practices

• During CFC chart creation, never copy a block icon between hierarchies without immediately re-checking the S7_area attribute.
• Configure OS area rights for the operator role based on the plant hierarchy, not the individual tag list. This avoids the asymmetry where one tag slips through.
• Include the trend Save operator workflow in the loop-check procedure. A pre-acceptance check should confirm that each operator role can save at least one trend group on every OS client.
• Document the Enter-then-OK input sequence in the OS operator manual and in the on-screen help (if configured via the AOTC Comment attribute).
• Maintain a single source of truth for OS area assignments: a CSV exported from the engineering station listing every block icon and its area. A delta review each maintenance window catches orphans before they reach operations.

13. Frequently Asked Questions