Configuring DCOM Handshakes and OPC Core Components for OpenPCS 7

When connecting a third-party OPC DA client to an OpenPCS 7 Server over DCOM, the error 'the server did not indicate that it was ready to receive connections' occurs when the OpenPCS 7 service (sopc_server.exe) starts but aborts its DCOM class registration. This failure occurs if WinCC Runtime is not fully active, server data packages are missing, or DCOM Identity is misconfigured. Do not install third-party OPC Core Components on the OpenPCS 7 server; Siemens installs certified, tested versions automatically. Resolve the error by ensuring WinCC Runtime is active, configuring OpenPCS 7 Server DCOM Identity to 'The Interactive User' or a dedicated SIMATIC HMI user, and opening TCP port 135 and dynamic RPC ports.

OpenPCS 7 DCOM Architecture: Class Registration and OPCEnum

SIMATIC OpenPCS 7 (6ES7658-0CX58-0YB0) provides standard OPC interfaces (OPC DA, OPC HDA, OPC A&E, and OPC UA) to exchange live process telemetry, historical trends, and alarm messages with third-party MES, ERP, and SCADA systems. When operating classic OPC DA over Distributed Component Object Model (DCOM):

The third-party client connects to the Windows RPC endpoint mapper (TCP port 135) on the OpenPCS 7 host.
The client queries the OPCEnum service to resolve the ProgID (OPC.SimaticNET) to its Class ID (CLSID).
DCOM launches the OpenPCS 7 executable (sopc_server.exe / sopcds.exe).
The OpenPCS 7 server initializes internal handles, connects to the local WinCC DataManager, and calls CoRegisterClassObject to signal readiness to DCOM.
If sopc_server.exe aborts its startup handshake, DCOM returns the error: 'The server did not indicate that it was ready to receive connections' (Error code 0x80004005 or CO_E_SERVER_STOPPING).

Why Installing Third-Party OPC Core Components on Servers Is Discouraged

Engineers frequently ask whether they should download and install the generic OPC Core Components Redistributable from the OPC Foundation website onto the OpenPCS 7 server. In SIMATIC PCS 7, the official rule is:

Do NOT install standalone third-party OPC Foundation Redistributables on a Siemens OpenPCS 7 or WinCC server.

When OpenPCS 7 or WinCC is installed, the Siemens setup automatically installs certified, hardened builds of the OPC Core Components and OPCEnum. Installing third-party packages overwrites Siemens-registered proxy/stub DLLs (opcproxy.dll, opccmn_ps.dll) and can disrupt internal WinCC communications and HMI faceplate operation. The third-party client PC does require OPC Core Components, but the server must remain on Siemens-supplied binaries.

Root Causes of 'Server Did Not Indicate Readiness' Errors

Three predominant system conditions prevent OpenPCS 7 from completing its DCOM readiness handshake:

WinCC Runtime Inactivity: OpenPCS 7 is an abstraction gateway; it does not store process tags. If WinCC Runtime is inactive, or if the OpenPCS 7 station has not imported server data packages (*.pck) from the OS Servers, sopc_server.exe cannot attach to the WinCC DataManager and exits immediately.
DCOM User Identity Mismatch: If the DCOM identity in dcomcnfg is configured as 'The Launching User', the server attempts to launch under the remote client's network credentials. If that user does not exist locally with identical passwords and membership in SIMATIC HMI, launch fails.
Missing OpenPCS 7 License: If the required OpenPCS 7 license key is missing in Automation License Manager, the server terminates after a brief startup check.

Step-by-Step DCOM Configuration and Identity Tuning in dcomcnfg

Configure DCOM properties on the OpenPCS 7 server machine to enable reliable third-party client connections:

Launch Component Services: Press Win+R, type dcomcnfg, and press Enter.
Navigate to DCOM Applications: Expand Console Root -> Component Services -> Computers -> My Computer -> DCOM Config.
Configure OPCEnum Properties:
- Locate OPCEnum, right-click and select Properties.
- On the Security tab, under Launch and Activation Permissions, select Customize -> Edit.
- Add Everyone, ANONYMOUS LOGON, and Interactive User; grant Local Launch, Remote Launch, Local Activation, and Remote Activation.
Configure OpenPCS 7 Server Properties:
- Locate OpenPCS 7 Server (or SIMATIC OpenPCS 7).
- On the Identity tab, select The Interactive User (if an operator is always logged into the server desktop) or select This user and enter a dedicated local Windows administrator account that belongs to SIMATIC HMI and SIMATIC NET.
- On the Security tab, grant full Remote Access and Remote Activation permissions to the client user.
Windows Firewall Rules: Open TCP port 135 (RPC Endpoint Mapper) and configure a rule allowing sopc_server.exe and opcenum.exe through the firewall.

OpenPCS 7 Server DCOM and Network Configuration Matrix

The following table details system requirements and settings for OpenPCS 7 connectivity:

Configuration ParameterOpenPCS 7 Server SettingClient Workstation SettingConsequence of MisconfigurationOPC Core ComponentsSiemens native (Do not overwrite)Install OPC Foundation RedistributableOverwriting server DLLs disrupts WinCCDCOM IdentityInteractive User or Defined SIMATIC UserLaunching UserServer fails readiness handshake (0x80004005)WinCC Runtime StateFully Active (Activate in WinCC)N/A (Client connects remotely)Server terminates immediately upon launchLocal User GroupsUser in SIMATIC HMI, Distributed COMIdentical account & passwordAccess Denied error 0x80070005Firewall PortsTCP 135 + Dynamic RPC rangeOutbound RPC enabledConnection timeout; server discovery fails

[!NOTE]
Commercial Accuracy Notice: SIMATIC OpenPCS 7 requires a dedicated software package license (6ES7658-0CX58-0YA5). > Client connections consume OpenPCS 7 tag/station authorizations. Always verify client connection limits and license > entitlements against official Siemens catalog documentation.

Verification

Verify that the third-party client connects cleanly to OpenPCS 7:

Local OPC Scout Validation: On the OpenPCS 7 server, open SIMATIC NET OPC Scout V10. Browse local servers, connect to OpenPCS 7, and monitor tags. Confirm clean local acquisition.
Remote Client Connection: Launch the third-party OPC client on the remote PC. Browse the server host via IP/hostname. Confirm that OPCEnum successfully discovers the OpenPCS 7 server CLSID.
Tag Subscription: Add process tags to an active group. Verify that tag values update cyclically with Quality Good without triggering DCOM timeout popups.

Limitations and Operational Precautions

Observe these guidelines when operating OpenPCS 7 with third-party clients:

Avoid Workstation Multi-Tenancy: When OpenPCS 7 is installed on an active WinCC client workstation, configure DCOM identity carefully to ensure client crashes do not disrupt operator faceplate responsiveness.
Prefer OPC UA for Modern Integration: Classic DCOM is notoriously sensitive to Windows security patches (such as Microsoft DCOM hardening updates CVE-2021-26414). For new integrations, deploy the OpenPCS 7 OPC UA Server interface to eliminate DCOM entirely.
Network Routing: Ensure the Terminal Bus network provides low-latency communication (<10 ms) between client and server.

Engineer FAQ

Should I install the OPC Core Components on my OpenPCS 7 server?

No. The Siemens OpenPCS 7 setup installs certified, tested versions of OPC Core Components automatically. Installing generic third-party redistributables can overwrite Siemens DLLs and disrupt WinCC.

What does 'the server did not indicate that it was ready to receive connections' mean?

DCOM launched the server process, but the process aborted before registering its class with DCOM. The most common cause is WinCC Runtime being inactive or DCOM identity permissions being rejected.

Why can't my client browse the list of OPC servers on the machine?

OPCEnum is blocked by Windows Firewall, lacks DCOM launch permissions, or is disabled in Windows Services. Grant Remote Launch/Activation to Everyone in OPCEnum properties.

How do Microsoft DCOM Hardening patches affect OpenPCS 7?

Microsoft security updates require packet-level authentication (RPC_C_AUTHN_LEVEL_PKT_INTEGRITY). Verify that your third-party OPC client supports DCOM packet integrity, or migrate to OPC UA.