Troubleshooting WinCC VBScript ADODB.Connection Syntax Errors

Problem Overview

WinCC VBScript projects frequently fail at runtime with the message Script Error ??, ActiveX component can't create object, or Object required: 'connextion'. The typical trigger is a malformed ADO database call inside a WinCC picture, global action, or scheduled C-script converted to VBS. The most common root causes observed in fielded systems are:

• Misspelled automation object names (e.g. ADODB.connnextion instead of ADODB.Connection).
• Assignment of a recordset to a non-existent object variable (Set rst = connextion).
• Missing On Error Resume Next / line-tag tracing so failures are invisible.
• Database provider mismatch (SQL Native Client vs ODBC Driver 17 for SQL Server).
• VBScript runtime host blocked by enhanced security configuration in WinCC 7.4 SP1 and later.

Root Cause Analysis

The WinCC Global Script editor and the picture-event handler compile VBScript at runtime against the Windows Script Host COM components. When CreateObject("ADODB.Connection") is invoked, WinCC calls CoCreateInstance on the ADODB CLSID. If the casing is wrong (VBScript is case-insensitive but the underlying COM registration is not), the API still finds the class but subsequent property accessors raise error 800A01AD "ActiveX component can't create object" or 800A01C9 "Object required".

Three failure modes account for roughly 90% of the reported cases:

Reference Implementation (Siemens Official)

Siemens application example 26283062 — "VBScript database connection in WinCC" is the canonical reference. The verified working pattern is reproduced below with annotated corrections:

Corrections applied vs. the original poster's broken script:

1. Spelling ADODB.connnextion -> ADODB.Connection. The reference string must match the COM ProgID registered in HKEY_CLASSES_ROOT\ADODB.Connection\CLSID.
2. Removed Set rst = connextion. A recordset must be assigned the result of Execute() or Open(), never the connection object itself.
3. Added Option Explicit to force declaration of all variables (turn on via WinCC Global Script editor menu: Tools -> Options -> Require Variable Declaration).
4. Added HMIRuntime.Trace breadcrumbs so the line at which execution stops is logged to the WinCC diagnosis file WinCC_Sys_.log.

Step-by-Step Troubleshooting Procedure

1. Reproduce the error in isolation. Open WinCC Explorer, launch Graphics Designer, place a button on the desired picture, and bind the click event to the suspect VBS action. Press F5 to start Runtime and trigger the script.
2. Capture the runtime error code. When the "Script Error ??" dialog appears, copy the hex code from the message line. Typical values are listed in the table above.
3. Enable WinCC trace. In WinCC Explorer, open Computer -> Properties -> Graphics Runtime -> Troubleshooting and set the script trace directory (default C:\Program Files (x86)\Siemens\Automation\WinCC\Diagnose). Restart Runtime.
4. Wrap the procedure with an error handler. Insert On Error Resume Next at the top of the action and replace HMIRuntime.Trace "OK" with structured logging (see next section).
5. Verify spelling of automation object names. Compare every CreateObject argument against the canonical list documented in Siemens FAQ 26283062. The reference uses ADODB.Connection, ADODB.Recordset, ADODB.Command, ADODB.Stream.
6. Validate the ODBC DSN. Run odbcad32.exe from the WinCC server. Test the connection using the same credentials used in the script. If the test fails, fix the SQL user permissions first; the VBS error will never go away while the DSN itself fails.
7. Re-register the ADO type library. From an elevated command prompt run regsvr32 "C:\Program Files\Common Files\System\ado\msado15.dll". Restart WinCC Runtime.
8. Confirm VBScript runtime is enabled. On Windows Server 2016 / 2019, the optional feature Win32-ScriptHost can be removed by group policy. Re-enable via Server Manager -> Add Roles and Features -> Features -> Server Side Script Host.

Defensive Scripting Template

The script below combines On Error Resume Next, line tagging via an internal tag, and structured trace output. Use it as the starting template for any database-bound WinCC VBS action.

ADO Provider Compatibility Matrix

Siemens officially supports SQLNCLI11 for WinCC 7.4 and MSOLEDBSQL.1 for WinCC 7.5 SP2 onward. See the WinCC V7.5 SP2 release notes on the Siemens Industry Online Support portal for the certified combinations.

Permission and DCOM Checklist

Database calls fail with cryptic COM errors when launch and access permissions are not granted. Verify the following on every WinCC server and WinCC client that runs the script:

1. The Windows user running the WinCC Runtime service is a member of the local group SQLServerMSSQLUser$<SERVER>$MSSQLSERVER or has been granted db_datareader / db_datawriter on the target database.
2. DCOM default launch and access permissions include the WinCC service account. Open dcomcnfg.exe → Component Services -> Computers -> My Computer -> DCOM Config, right-click Microsoft OLE DB Provider for SQL Server and add the service account to Launch and Activation and Access.
3. Antivirus / EDR is not blocking vbscript.dll or msado15.dll. Some enterprise agents (CrowdStrike, Defender ASR rules) quarantine child processes spawned by CCExplorer.exe — add the WinCC installation folder as an exclusion.
4. For WinCC 7.5 SP1 and newer, enable the registry value HKLM\SOFTWARE\Wow6432Node\Siemens\WinCC\Diagnostics\ScriptTrace = 1 (DWORD) before starting Runtime.

Error Code Reference

Verification Procedure

1. Runtime smoke test. Trigger the action; the Script.Trace internal tag should display OK at 40_Close. If a failure string is shown, the suffix indicates the offending step.
2. Trace file inspection. Open C:\Program Files (x86)\Siemens\Automation\WinCC\Diagnose\WinCC_Sys_01.log. Search for VBS — every HMIRuntime.Trace line will be present with timestamp and source line number.
3. Process Monitor audit. If the error remains, run Process Monitor filtered on CCExplorer.exe and msado15.dll to confirm LoadLibrary succeeds. NAME NOT FOUND results indicate a corrupted or blocked DLL.
4. Independent ADO test. From the same machine, open a Command Prompt and run a small VBS file: cscript //NoLogo C:\test\ado_probe.vbs. The probe should attempt CreateObject("ADODB.Connection") against the same connection string and report success. If the probe fails, the issue is environmental, not in WinCC.
5. Service account check. Use whoami /groups from a Command Prompt launched under the WinCC service account (Sysinternals Psexec) and confirm database login permissions.

Common Edge Cases and Field Notes

• Periodic "Script Error" every 5–10 minutes. This pattern is unrelated to VBS source code and is caused by a runaway web browser control in WinCC WebNavigator or a popup from HtmlHost.exe. The Microsoft Q&A thread "Don't know how to get rid of a script error that appears every 5-10 minutes" documents the same dialog appearing with a white background and Yes/No buttons; the fix is to disable script debugging in Internet Explorer (Tools -> Internet Options -> Advanced -> Disable script debugging) or upgrade to WinCC 7.5 SP2 which replaces the WebClient active X control.
• Works in the editor, fails at Runtime. The Global Script editor runs under the interactive user; Runtime runs under the system account CCAdmin. Permissions to the SQL server differ. Always verify under Runtime.
• 64-bit / 32-bit mismatch. WinCC V7.x is 32-bit. Even on a 64-bit OS you must install the 32-bit OLE DB provider and create the DSN with the 32-bit C:\Windows\SysWOW64\odbcad32.exe. Mixing providers returns 0x800A0E7A.
• Power loss / unclean shutdown. If the SQL Server hosting the WinCC archive database restarts unexpectedly, the first ADO call from a still-running Runtime may return 0x80004005. Wrap every con.Open in a retry loop with exponential back-off (200 ms, 400 ms, 800 ms).
• Circular reference between tags and scripts. Writing to a tag inside the same script that reads it can deadlock Runtime. Use intermediate memory tags.
• Variable not declared when Option Explicit is on. Activate it via Tools -> Options in Global Script editor; VBS will refuse to compile any undeclared identifier.

Performance Considerations

Database calls are blocking. A long-running SELECT in a picture-level event freezes the Graphics Designer thread for the full duration. Best practice from the Siemens WinCC Performance Guideline:

• Move all database operations into a scheduled global action triggered by a timer (default 1 s, increase to 5–10 s if the query is heavy).
• Open the connection once at project startup, store it in a process-global variable using Application.Variables, and reuse the handle.
• Cap result sets with TOP n in the SQL string to avoid streaming the entire archive.
• Index the columns referenced in WHERE clauses; a missing index on Tag in the WinCC archive schema can add seconds to every read.

Upgrade Path Recommendations

WinCC 7.0 / 7.1 (released before 2010) reach end of support and rely on legacy SQL Native Client 10. Upgrade to WinCC 7.5 SP2 (or newer) and migrate the database provider to MSOLEDBSQL.1 simultaneously. The WinCC compatibility tool CCConfigExplorer.exe validates the new provider string and updates all *.MOF files automatically. Refer to the WinCC V7.5 SP2 release notes on the Siemens Industry Online Support portal for the migration checklist.