WinCC 7.0 SP3 Analog Tags Not Showing on Client: Troubleshooting

Problem Statement

A WinCC V7.0 SP3 Update 8 distributed SCADA installation exhibits a selective visibility fault: the redundant server pair displays analog process values correctly, all three client stations read digital tags correctly, yet none of the clients render the analog (real/floating-point) tag values. Digital binary tags continue to update on every client, which eliminates a generic network, licensing, or project-load failure and points instead to a tag-type-specific configuration or server-package staleness condition.

This article documents the field-proven diagnostic and remediation sequence for the analog-tag-on-client failure mode in a WinCC V7.0 SP3 redundant server / multi-client topology. The same root-cause classes apply to WinCC V7.0 SP2, SP4, and the V7.2 / V7.3 / V7.4 branches that share the server-package architecture.

Affected Environment and Versions

The "pascc" naming pattern referenced in the field report corresponds to the PAS (Process Automation System) tag naming convention used when the WinCC project integrates S7 AS (Automation Station) variables through the SIMATIC S7-417/H or S7-400F/FH AS pool. Analog and digital differentiation within the AS pool follows the configured data type (REAL, INT, BOOL) at the PLC, but the way WinCC packages and synchronises them on the client is governed by the server package generation timestamp.

System Topology

Symptom Matrix

Root Cause Analysis

Four primary root-cause classes produce the reported symptom pattern. Rank them in the order shown because the first two resolve more than 90 % of field cases.

1. Stale server package after engineering change. The user explicitly states that "this happened after the new regulations were added to the project." A server package generated before the new tag set (analog tags, especially those added under a PAS namespace) was compiled does not contain those tag definitions. The client loads the package, sees the old tag table, and resolves analog values to quality BAD / no connection.
2. Acquisition / archiving / display cycle mismatch on analog tags. Analog tags in WinCC have three independent cycle definitions. If the acquisition cycle is configured for "on demand" or set to a value larger than the client's polling window, the client will display the initial value forever. Digital (BOOL) tags often use a fast 250 ms or 500 ms cycle by default and therefore appear to work.
3. Redundancy pairing mismatch. The redundant server package is generated on the master and replicated to the standby; if the standby has not yet synchronised the new package before the client requests it, the client may load a partial image.
4. Tag type / namespace mismatch (PAS vs raw S7). PAS-scope tags from the AS pool use the WinCC server-side symbolic resolution path. If the client has no licence or project rights to the PAS namespace (only the S7 namespace), the package resolves digital tags (which are imported as raw BOOL) but cannot resolve the PAS-mapped analog tags.

Diagnostic Procedure

Execute the steps in order. Do not skip the early checks — they are cheap and frequently conclusive.

1. Open SIMATIC Shell on every client. Verify that both servers and all three clients are visible. If any computer is missing, fix Windows network and DNS first; the symptom you are seeing will resolve itself once the clients can see the servers. Reference: SIMATIC WinCC in a Windows network — requirements.
2. Confirm identical Windows user name and password on every server and client. WinCC uses NTLM-style authentication for server data access. Mismatched credentials silently fail the server-package load and the client silently shows only the locally cached digital tags.
3. Validate computer names. Reference: Restrictions for assigning computer names for WinCC. Forbidden: names longer than 15 characters (legacy), hyphens at the start, underscores, Unicode, identical names across the project.
4. Open WinCC Explorer on the server. Navigate to Server Data → Server Package. Note the timestamp and the tag count in the package versus the count in the live Tag Management tree.
5. Compare tag counts. On the server: right-click Tag Management → Properties → count analog tags. On the client, open the loaded .pck file or the Server Data view — the analog tag count must match.
6. Use the WinCC Channel Diagnosis tool (s7dismux / Channel Diagnosis applet). Look for "connection established" against the PLC and read the diagnostic buffer of the S7 channel DLL.
7. Inspect tag quality codes on the client. In WinCC Explorer on the client, open Tag Management → <channel> → <connection>. Right-click the analog tag → Properties. If the "Last error" field shows 0x80070005 (access denied) or 0x80070002 (not found), the package is stale.
8. Check the WinCC SysLog at C:\Program Files (x86)\Siemens\Automation\WinCC\Diagnose\WinCC_SysLog.log. Search for SERVERPACKAGE, PAS, and DataManager entries with the current date.

Solution 1 — Regenerate and Reload the Server Package

This is the dominant fix when analog tags were added after the previous server package generation.

1. On the server, close the WinCC Runtime.
2. In WinCC Explorer, right-click Server Data → Server Package.
3. Select Generate Server Package. Wait for the message Server package successfully created in the status bar.
4. Copy the resulting <ProjectName>.pck file from the server's \<server>\<project>\Server\<servername>\Package\<computername>.pck share to the equivalent path on each client. Alternatively, on the client right-click Server Data and choose Load Server Package; the client connects to the server, downloads the latest package, and applies it.
5. Restart the WinCC Runtime on each client.

Solution 2 — Verify Tag Configuration (Acquisition, Archiving, Display)

For each analog tag missing on the client, open its properties and verify:

• Type matches the PLC data type (REAL → floating-point with 32-bit length).
• Acquisition mode is "on change" or a defined cycle, not "never".
• Substitute value usage is not set to "always substitute" unless intentional.
• Limit values are within the data type range. Out-of-range values cause quality BAD on the client.

If the analog tag is to be logged, verify in Tag Logging that the tag is selected in at least one archive. Tags not in an archive can still be displayed but can appear greyed out on some faceplates; this is not the failure mode here, but worth ruling out.

Solution 3 — Redundant Server Pair Verification

On each server, open WinCC Explorer and confirm:

1. Redundancy → Master / Standby is configured correctly.
2. The redundancy event log shows successful synchronisation after each project load.
3. The server package timestamp on both servers is identical. If they differ by more than a few seconds, force a resync by reloading the project on the standby.

Diagnostic command from the server's command prompt:

If synchronisation repeatedly fails on the analog tag namespace, the most common cause is that the AS (PLC) connection is configured only on the master. Switch the master to standby and observe whether analog tags continue to update on the client; if they do not, the connection is asymmetric and the standby is unable to refresh the analog tags from the PLC.

Solution 4 — Windows Network, Computer Name, and User Account Requirements

The official Siemens requirement documents are summarised below; reference them for full text.

Solution 5 — SIMATIC Security Control Reset

Reset the security settings on every computer in the project:

1. Start → Programs → Siemens Automation → SIMATIC → SIMATIC Security Control.
2. Click Edit → Restore default settings.
3. Apply, exit, and restart the computer.

This step frequently resolves hidden DCOM permission faults that block the server-package download specifically for the analog tag namespace, while leaving the digital tag namespace (which uses a smaller subset of the COM interfaces) operational.

Verification Checklist

Preventive Measures and Project Hygiene

• Make server package regeneration a mandatory step in every project change procedure. A server package is not auto-regenerated when tag definitions change.
• Use a domain account with identical credentials across the entire WinCC estate. Local accounts are a recurring source of "digital works, analog does not" because WinCC uses different COM endpoints for different tag types.
• Maintain computer-name conventions strictly: WINCCSRV01, WINCCSRV02, WINCCCLI01 — short, uppercase, alphanumeric only.
• Document every project change in a changelog entry that includes the engineering date and the server package regeneration date. Discrepancies between the two dates explain the vast majority of field tickets.
• Schedule a quarterly redundancy swap test to verify that both servers can independently refresh all tag types from the PLC.
• Back up the server package file alongside the WinCC project; this lets you roll back to a known-good package while you diagnose a new failure.

Edge Cases and Field-Proven Caveats

• Client-with-own-project vs client-without-own-project. A client without its own project loads only the server package and pictures from the server; if the analog tag is referenced in a picture that is not part of the package, the client shows the picture but the tag resolution still fails. A client with its own project loads both project data and the server package; mismatches between the two project files can mask analog tags even when the package is correct. Verify which model is in use.
• Tag Logging Runtime not started. Analog values used as archive inputs require Tag Logging Runtime. If only Graphics Runtime is active on the client, trend displays for analog tags show "no data" while real-time I/O fields show live values — a different symptom from the one reported here, but worth confirming.
• Scale conversion wrong. A correctly delivered analog value may display as 0.0 if the linear scale conversion on the client project overrides the server-side scale. Compare the tag's "linear scaling" property on server and client.
• Time zone differences. Servers and clients in different time zones occasionally cause the server package to be regenerated only when the server's local time crosses the engineering change date. Synchronise clocks via NTP and verify.

FAQ