WinCC Configuration Tool Fix 'Communication Driver Unknown' Error

Problem Overview

The Siemens WinCC Configuration Tool is an Excel-based SmartTool add-in (distributed with WinCC under Smart Tools > WinCC Configuration Tool) that allows editing of tags, connections, alarms, and limit-value monitoring rows of a WinCC project from outside the WinCC Explorer. The tool is frequently used to bulk-modify large tag lists without opening Graphics Designer or Tag Management.

A documented failure mode occurs when a project is created cleanly (no error during new project generation) but cannot be opened from a different workstation, or after a WinCC reinstallation. The tool launches Excel, mounts the project file, and immediately aborts with two companion messages:

1. Top-level dialog: "Not all limit value monitoring could be generated! Errors occurred while reading the object"
2. Reading Error tab (per-row entries):
   Table type: Connection table → Error text: "The communication driver set is unknown!"
   Table type: Tag table → Error text: "The set connection does not exist!"

Both messages block the import of the tag database; the user cannot view, edit, or export tags, and any pending CSV/Excel modifications cannot be re-imported into WinCC.

Affected Software Versions

Exact Error Messages and Where They Originate

The Excel workbook produced by the tool contains a hidden diagnostic tab called Reading Error (sometimes rendered ReadingError). Open it manually via right-click → Unhide if it is not visible. The two error classes encountered are:

The cascade is direct: the missing channel prevents connection enumeration, which in turn invalidates every tag bound to those connections. The limit-value monitoring row of the Reporting tabs is the first object the tool tries to rebuild from the WinCC database, which is why that error surfaces first.

Root Cause Analysis

The error is not caused by a broken tag, a corrupted MDF/SDF, or a registry ACL. In every reported case the underlying cause is one of the following:

1. Missing communication channel on the operator station running the Excel tool. The project was created on a WinCC engineering station with SIMATIC S7 Protocol Suite and MODBUS Serial installed; the operator station has only WinCC Runtime with a subset of channels. The configuration tool enumerates HKLM\SOFTWARE\Wow6432Node\Siemens\WinCC\ChannelUnits and the registry subkeys matching the project's connection records. When the key is missing, the error is thrown.
2. WinCC Custom Installation missing the channel. A typical custom install path under the WinCC 7.0 SP3 setup is WinCC Installation → Additional Languages / Options → Communication → SIMATIC S7 Protocol Suite. If the box was unchecked, the DLL is never registered with regsrv32.
3. Mixed project on a network share. WinCC project is stored on a UNC path (e.g., \\eng-pc\WinCCProj\PlantA) but the channel search path resolution expects the channel DLLs to be local under %ProgramFiles(x86)%\Siemens\Automation\WinCC\bin. A blocked UNC load throws the unknown-driver message.
4. Office 64-bit vs Configuration Tool 32-bit mismatch. The SmartTool is compiled against Excel 2003/2007 COM (32-bit only). With Office 64-bit the COM registration is correct but the add-in refuses to enumerate tags and silently degrades; some users perceive this as the same "driver set is unknown" symptom.
5. Project originally authored on a different WinCC version. For example, the project was created on WinCC 6.2 with the Channel APACS driver and later migrated to 7.0. The migration copies the connection records but the channel DLLs are version-mismatched or absent.

Diagnostic Workflow

Run the following checks on the workstation that hosts the failing Excel tool. Each step confirms or eliminates a candidate root cause before any destructive change is made.

1. Confirm the Excel add-in is loaded. Open Excel → File → Options → Add-Ins → Manage: COM Add-Ins → Go. Verify WinCC ConfigurationTool is present and enabled. If absent, re-register with regsvr32 "C:\Program Files\Siemens\Automation\WinCC\SmartTools\ConfigurationTool\CCConfigTool.dll" from an elevated command prompt.
2. Verify the channel DLLs exist on disk.

   dir "%ProgramFiles(x86)%\Siemens\Automation\WinCC\bin\Channel*.dll"

   Expected entries include ChannelS7.dll, ChannelModbus.dll, ChannelALL.dll. A missing entry is the smoking gun.
3. Inspect the WinCC channel registry hive.

   reg query "HKLM\SOFTWARE\Wow6432Node\Siemens\WinCC\ChannelUnits" /s

   Each installed channel exposes a subkey (e.g., \ChannelS7). If the channel referenced in the project is absent here, the tool will fail.
4. Read the project's connection list manually. Open <ProjectName>.mcp in the WinCC Explorer → Tag Management → [your driver] → Connections. Note the channel name and connection count. Cross-check the count against what the Excel tool reports as unknown driver set rows.
5. Open the WinCC Channel Diagnostics applet. Start → Siemens Automation → WinCC → Channel Diagnosis. It enumerates the same registry hive and reports Channel is registered / Channel is not registered for each known driver.
6. Check the Application event log (eventvwr.msc) under Siemens Automation source. Log entries such as Event ID 4900 confirm channel load failures at WinCC startup.
7. Verify Office bitness.

   reg query "HKLM\SOFTWARE\Microsoft\Office\<version>\Outlook" /v Bitness

   or simply File → Account → About Excel in Excel 2013+. It must read 32-bit for WinCC 7.0 SP3 SmartTools.

Solution Path A — Install the Missing Communication Channel

This is the fix in roughly 90% of incidents. The channel that the project uses must be present on the local disk and registered with Windows.

1. Insert the original WinCC 7.0 SP3 installation media (DVD or mounted ISO).
2. Run Setup.exe as Administrator.
3. When prompted, choose Modify / Add Components (the Repair path also works but reinstalls the full package).
4. Expand the tree: WinCC → Communication and tick the boxes for every channel used by the project (typically SIMATIC S7 Protocol Suite and OPC).
5. Click Next → Install. Setup registers the channel DLLs into %ProgramFiles(x86)%\Siemens\Automation\WinCC\bin and writes the registry subkeys.
6. Reboot. WinCC Runtime services must restart for the new channel to bind to the process.
7. Re-open the Excel ConfigurationTool and point it at the project.

Solution Path B — Re-register the Excel ConfigurationTool Add-in

If the channel is installed correctly but the COM bridge is broken (typically after an Office update), re-register the in-process server:

1. Close all Excel instances.
2. Open cmd.exe with Run as Administrator.
3. Execute:

   cd /d "%ProgramFiles(x86)%\Siemens\Automation\WinCC\SmartTools\ConfigurationTool"
   regsvr32 /u CCConfigTool.dll
   regsvr32 CCConfigTool.dll

4. Re-launch Excel and verify the add-in is enabled.

If the registration returns 0x80070005 (access denied), stop the WinCC CCAgent and WinCC Runtime services first; they hold handles on the DLL during shutdown.

Solution Path C — Repair the Project's Connection Records

When a project was authored on a workstation with a different set of channels and the source workstation is gone, you may have orphaned connection records that the target cannot resolve. The cleanest remedy is to rebuild the connection list:

1. Open WinCC Explorer on the target machine.
2. Right-click Tag Management → Add New Driver → select the correct channel (e.g., SIMATIC S7 Protocol Suite).
3. Open the new driver → right-click → New Connection → name it identically to the orphaned record (the Excel tool expects the same logical name).
4. Reassign the tags to the new connection via the Excel ConfigurationTool: load the project, ignore the warnings, then use the Search & Replace column on the tag sheet to update the connection reference from the old name to the new one.
5. Save the project. The Reading Error tab should now be empty.

Solution Path D — Clean Tag-Logging References

If the user has already attempted a fix and rebuilt connections but still sees a few hundred rows of "The set connection does not exist!" in the tag table, those are tags referencing a connection that no longer exists. The fastest cleanup is:

1. Open WinCC Explorer → Tag Logging → open the Archives node.
2. For every archive, verify the Tag Selection dialog shows only valid tags. Delete orphan tag references with the red exclamation mark icon.
3. Repeat for Alarm Logging → Message Classes → tag triggers.
4. Open the Excel tool, the Reading Error tab will be empty for the tag table.

Verification

After applying the fix, perform the following confirmation steps before declaring the workstation healthy:

1. Launch the WinCC ConfigurationTool from Start → Siemens Automation → WinCC → Configuration Tool. Excel opens with the project loaded.
2. Right-click the worksheet tabs → Unhide → select Reading Error. The sheet must be empty (no rows).
3. Switch to the Tag tab. The row count must equal Tag Management → All Tags in WinCC Explorer. If a delta exists, the rows correspond to internal Structure tags (e.g., @System) which the tool always hides — a difference of 30–80 rows is normal.
4. Edit a test cell, save, and re-open in WinCC Explorer. The change must be visible.
5. Start WinCC Runtime. The connection status icon in the Channel Diagnosis applet must turn green within the configured timeout (default 5 s).
6. Trigger one limit value from the PLC. The alarm must appear in Alarm Logging Runtime within 1 s.

Prevention Checklist

Troubleshooting Matrix

Related ConfigurationTool Behavior

Two ancillary behaviors often observed alongside the reported error are worth understanding:

• ConfigurationTool will not load a project in Read-Only mode from a UNC share. The WinCC Runtime must hold a Server license on the host that owns the project directory; the tool checks for the ProjectPath registry value in HKLM\SOFTWARE\Wow6432Node\Siemens\WinCC\Projects before mounting the workbook.
• ConfigurationTool tags include limits of 65 535 per workbook. Excel 2003 hard-limits at 65 536 rows; the tool emits a warning when the project exceeds that. Upgrade to Excel 2010+ and use the .xlsx format before re-running.
• Channel name resolution is case-sensitive. A connection named PLC1 in the project is looked up as PLC1 in the registry. Channels installed under SimaticS7 (no space) will not match Simatic S7.

FAQ