PCS7 IL Library Analog Tag Archiving: Troubleshooting Guide

Engineers integrating S7-300 controllers into SIMATIC PCS 7 using the IL (Individually Programmed Library) blocks frequently encounter two related faults: (1) the Archiving link button is missing from the AI faceplate, and (2) the WinCC OnlineTrendControl shows the runtime status Object will not be displayed for any tag past the first three configured trends. Both faults are rooted in the same configuration domain — the OS compile, the archive-tag generation, and the trend picture wiring. This guide consolidates the field-proven remediation steps for PCS 7 V7.x/V8.x, V9.0, and the TIA Portal Openness library-archiving contract so that trending, reporting, and long-term storage behave deterministically.

1. Problem Statement and Symptom Matrix

Three observable symptoms appear together or in isolation:

Symptom S1 is cosmetic when manual archive tags exist (the operator can still open the WinCC OnlineTrendControl from the picture), but symptom S2 is the one that breaks batch trending and reporting, because the WinCC UserArchive / SQL export depends on a one-to-one connection between the trend row and an archive tag.

2. Root Cause Analysis

2.1 Why the Archiving button disappears from the IL AI faceplate

The IL family differentiates itself from APL at the faceplate level: APL generates an archive tag per measurement at the first OS compile and re-binds it on every subsequent compile. IL does not perform this auto-binding unless the OS-level option "Create/Update Archive Tags" is enabled. When the option is disabled, the faceplate's Open Archive View script has no valid WinCC archive tag to resolve, and the button is either hidden or greyed. This is by design — IL was created for projects where archive structure is defined manually so that PCS 7 does not implicitly grow the archive database.

To verify the diagnosis:

1. In SIMATIC Manager, right-click the OS (e.g., OS1).
2. Choose Properties → Archive.
3. Confirm the checkbox "Create/update archive tags" is selected.
4. Trigger an OS compile (entire).

If the option is already selected but the button is still missing, the archive tags exist but the faceplate script is bound to a different WinCC variable namespace — typically because the project was migrated and the prefix @ lost its leading underscore. Re-compile the OS with the option enabled and the button reappears.

2.2 Why exactly three trends connect, then "Object will not be displayed"

The behavior of first 3 OK, rest failing is the classic fingerprint of one of the following:

• Trend picture copy without re-binding. When you copy a .pdl containing an OnlineTrendControl, WinCC retains the internal C-script tag trends[i].TagName for the first three rows but loses the connection object for the rest. The status string Object will not be displayed is the VBS error returned when the C-tag handle is uninitialised.
• Archive tags not selected via the browse dialog. Manually typing a tag name in the Tag Name field of a trend row produces a syntactically valid binding only if the tag exists and is an archive tag (not a process tag). If the tag is a plain process tag, the dialog accepts it during configuration but the runtime connection drops to Object will not be displayed.
• Stale client-side server-data cache. On multi-OS / OS-Client topologies, the client downloads a static copy of the server's tag logging at startup. If the server has new archive tags (added by an OS compile) but the client has not refreshed, the client only sees the original three archive tags.

3. Solution Procedure

3.1 Restore the Archiving button on the IL faceplate

1. Open the OS in the WinCC Explorer of the engineering station.
2. Navigate to Tag Logging and verify whether the analog measurements are listed under the archive.
3. If they are absent, return to SIMATIC Manager, right-click the OS, choose Properties → Archive and tick Create/update archive tags (path: OS Properties → "Archive" tab → "Create/update archive tags").
4. Recompile the OS entirely (PLC → Compile and Download Objects → OS → Entire OS).
5. Re-open the WinCC picture and verify the AI faceplate shows the Archiving button.

3.2 Resolve Object will not be displayed beyond the third trend

1. Open the OnlineTrendControl in the Graphics Designer.
2. For every trend row beyond the third, click the row, then click Selection in the configuration dialog.
3. In the Tag Selection dialog, browse the archive tags (not the process tags). The dialog has two views: Process Tags and Archive Tags. Make sure the Archive Tags view is active.
4. Re-select the tag using the dialog, not by typing. Manually entered names are accepted at design time and break at runtime.
5. Save the picture, close the Graphics Designer, and trigger an OS delta compile.
6. On the OS Client, choose Server Data → Update in the WinCC Explorer to refresh the cached tag logging view.

If the same fault persists for newly created OnlineTrendControl instances (i.e., not just copied ones), the cause is the Create/update archive tags option in OS properties. Re-enable it and re-compile.

3.3 Manual archiving fallback when auto-archive is disabled

Some regulated projects require that no WinCC archive tags are created automatically. In that case, archive tags must be created by hand. The procedure is documented in the WinCC V7.5 manual Properties of archive tags (binary, analog, text):

1. Open WinCC Explorer → Tag Logging.
2. Right-click Archive and choose New Archive.
3. Right-click the new archive, choose New Tag, and set:
   • Name: AI_<TAGNAME>_ARC
   • Type: Analog for AI blocks, Binary for DI blocks, Text for messages
   • Source: the underlying process tag (e.g., the IL block's OUT value)
   • Acquisition cycle: match the OS cycle (1 s, 2 s, 5 s, 10 s, 1 min)
4. Repeat for every measurement that must appear in the report.
5. In the trend picture, browse the new archive tags and bind them to the trend rows.

4. Verification and Acceptance Test

After applying the fix, run the following acceptance test before returning the plant to operation:

5. Diagnostic Reference Tables

5.1 Runtime status messages of OnlineTrendControl

5.2 OS property matrix

6. PCS 7 / WinCC Version Specifics

The exact location of the Create/update archive tags option shifts across versions. Use the table below as a quick lookup.

For TIA Portal-hosted PCS 7 projects, the same Create/update archive tags option governs the WinCC Professional / WinCC Runtime Advanced archive engine. The library backup format follows the contract documented at Archiving and retrieving a library (TIA Portal Openness) — only the .zalx and .zal14 extensions are accepted by the TIA Portal Openness API; archives created with other extensions cannot be retrieved from TIA Portal.

7. Working Configuration Snippets

7.1 VBScript to force Server Data Update on the OS Client

This script can be scheduled as a WinCC action to refresh the client cache after every OS compile:

' Force the client to refresh the server-side tag logging cache
Dim objTagLog
Set objTagLog = HMIRuntime.Tags("@ServerDataUpdate")
objTagLog.Write 1
Set objTagLog = Nothing
HMIRuntime.Trace "Server data refresh requested at: " & Now

7.2 C-script to enumerate failed trend rows

Use this in the OnlineTrendControl picture to log all rows whose runtime status differs from Connection OK:

// Iterate over the trend rows and report any non-OK status
int i;
char szStatus[64];
for (i = 0; i < 8; i++) {
    GetTrendStatus(i, szStatus, sizeof(szStatus));
    if (strcmp(szStatus, "Connection OK") != 0) {
        printf("Trend row %d status: %s\r\n", i, szStatus);
    }
}

8. Common Pitfalls and Field-Proofing Notes

• Do not copy trend pictures without re-binding. The C-tag handle survives a copy, but the underlying archive tag is re-evaluated against the destination OS's tag namespace. Always re-select via the browse dialog after a copy.
• Do not type tag names in the trend configuration dialog. The dialog validates syntax, not semantic correctness. A process tag typed in the row will configure successfully but fail at runtime with Object will not be displayed.
• Do not mix IL and APL blocks in the same picture. They share the same tag prefix but write to different archive namespaces; the trend picture's Tag Selection dialog filters by namespace and may hide valid tags from the other library.
• Always re-compile the OS entirely after toggling the Create/update archive tags option. A delta compile keeps stale archive bindings.
• Keep the WinCC Runtime and the OS server build consistent. Mixing, for example, a V9.0 server with a V8.2 client produces a tag-namespace mismatch that mirrors the Object will not be displayed symptom but is not resolved by re-binding.

9. Escalation Checklist

If symptoms persist after the steps above, escalate with the following artefacts:

1. PCS 7 version and OS compile log (OS_Compile.log in the project directory).
2. WinCC version and SP level (e.g., WinCC V7.5 SP1 Update 5).
3. Library versions: IL, APL, plus any custom library.
4. CPU type and firmware (e.g., CPU 315-2 PN/DP, firmware V3.3).
5. Output of the trend row enumeration C-script (Section 7.2).
6. WinCC diagnostic files from WinCC Explorer → Tools → Diagnostics.

10. Related Configuration: Report Designer Binding

Even with archive tags generated, the SIMATIC PCS 7 Report Designer requires its own binding:

1. Open the report template in Report Designer.
2. For each cell that displays a historical value, choose Data Source → Archive Tag.
3. Pick the archive tag, not the process tag.
4. Set the time range (Last 8 hours, Shift, etc.) and the aggregation function (Average, Min, Max, Sum).
5. Save and trigger a test print.

11. Summary

The two recurring faults in this guide are fixed by a small set of actions: enable Create/update archive tags in the OS properties for IL projects, re-bind trend rows through the archive-tag browse dialog (never by typing), and refresh the client-side server data after every OS compile. With those three actions, the Archiving button returns to the IL AI faceplate, the Object will not be displayed status disappears, and the PCS 7 Report Designer receives the archive-tag bindings it needs to render historical rows. The same pattern applies whether the project is hosted in SIMATIC Manager or in TIA Portal, with the Openness library-archive contract (.zalx, .zal14) governing the TIA-side artifacts.