Integrating SCALANCE Switches into PCS 7 Maintenance Station via OPC and SNMP

In SIMATIC PCS 7 Maintenance Station (MS), network switches located on the Plant Bus or Terminal Bus (such as SCALANCE X208 or X-308-2) are not configured in CPU Hardware Configuration; instead, they are monitored via Simple Network Management Protocol (SNMP) through the SIMATIC NET OPC Server configured on the Maintenance Station PC. If switch diagnostic screens display only IP addresses and hostnames without hardware information (such as MLFB order numbers, serial numbers, or port status), the issue is typically caused by an incorrect device profile selected in the OPC Server SNMP configuration, disabled SNMP on the switch, or a known SNMP MIB parser defect in base PCS 7 V9.0 that was resolved in PCS 7 V9.0 SP1.

Network Device Monitoring Topology: Fieldbus vs Plant Bus

SIMATIC PCS 7 Maintenance Station provides hierarchical asset management across automation hardware, field devices, and network infrastructure. However, the engineering mechanism used to integrate network switches depends strictly on their network tier:

Fieldbus Switches (PROFINET IO): Switches operating on the fieldbus tier (such as SCALANCE X204IRT or XC208 connecting ET 200 distributed I/O to the S7-400 CPU) are configured directly in STEP 7 HW Config under the controller's PROFINET IO system using their GSDML files. Controller diagnostic drivers (MOD_D1, MOD_SW) automatically generate Maintenance Station diagnostics.
Plant Bus and Terminal Bus Switches: Switches operating on the Industrial Ethernet Plant Bus or Terminal Bus (e.g., SCALANCE X208, X-308-2, XR-300, XM-400) do NOT connect to the CPU PROFINET master. Instead, they are network infrastructure devices. They must be monitored out-of-band via SNMP using the SIMATIC NET OPC Server (SNMP) running on the Maintenance Station or OS Server PC station.

Root Causes of Missing SCALANCE Device Information

When a SCALANCE switch appears in the Maintenance Station overview with its IP address and name but lacks extended asset attributes (MLFB order number, serial number, hardware revision, and port link states):

Device Profile Mismatch: In the OPC Server SNMP configuration tab, each network node must be assigned a specific device profile text file (e.g., Profile_SCALANCE_X200_Vxy.txt for X200 series or Profil_SCALANCE_X300X400_Vxy.txt for X300/X400 series). If a generic profile (such as Profile_MIB-II.txt) is selected, the OPC server can only query basic TCP/IP parameters (sysName, sysDescr) and cannot interpret Siemens-specific enterprise MIB OIDs.
SNMP Community String and Read Access: The SCALANCE switch Web-Based Management (WBM) must have SNMPv1/v2c enabled with the Read Community string matching the OPC configuration (default: public). If community strings differ, the switch rejects SNMP GET requests.
PCS 7 V9.0 Base Version SNMP Defect: PCS 7 V9.0 base release contained a known issue in the WinCC Maintenance Station faceplate scripts where dynamic refresh queries timed out against certain SCALANCE firmware versions. Siemens resolved this behavior in PCS 7 V9.0 SP1 and SIMATIC NET PC Software V14 SP1.

SCALANCE Switch Integration and Profile Reference Matrix

The following table summarizes profile assignments and integration parameters for common SCALANCE switch families:

Switch FamilyExample MLFBNetwork Bus TierIntegration MethodRequired SNMP Device ProfileSCALANCE X-2006GK5208-0BA00-2AA3Plant / Terminal BusSIMATIC NET SNMP OPCProfile_SCALANCE_X200_Vxy.txtSCALANCE XC-2006GK5208-0BA00-2AC2Plant Bus or FieldbusSNMP OPC or PROFINET GSDMLProfile_SCALANCE_XC200_Vxy.txtSCALANCE X-3006GK5308-2FL00-2AA2Plant Bus BackboneSIMATIC NET SNMP OPCProfil_SCALANCE_X300X400_Vxy.txtSCALANCE XM-4006GK5416-4GS00-2AM2Core Plant BackboneSIMATIC NET SNMP OPCProfil_SCALANCE_X300X400_Vxy.txtSCALANCE X-200IRT6GK5204-0BA00-2BA3Fieldbus Tier (IO)STEP 7 HW Config (PROFINET)Configured in HW Config (No SNMP profile required)

Step-by-Step Configuration of SIMATIC NET SNMP OPC Server

To configure SCALANCE switch asset monitoring on the PCS 7 Maintenance Station:

Enable SNMP on SCALANCE Switch:
- Log into the SCALANCE Web-Based Management (WBM) using a web browser.
- Navigate to System -> SNMP.
- Enable SNMPv1/v2c. Set the Read Community string to public (or your plant's standard community string).
- Save and apply changes.
Configure OPC Server in PC Station HW Config:
- In SIMATIC Manager, open the Hardware Configuration of the Maintenance Station PC Station.
- Double-click the OPC Server application module (slot 1 or designated slot).
- Navigate to the SNMP tab.
- Click Add Device.
- Enter the Device Name, IP address of the SCALANCE switch, and the Community string (public).
- In the Device Profile drop-down, select the exact profile matching your switch model:
- For X208: Profile_SCALANCE_X200_Vxy.txt
- For X-308-2: Profil_SCALANCE_X300X400_Vxy.txt
- Save and compile the PC station hardware configuration.
Update Diagnostic Screens and Compile OS:
- In SIMATIC Manager Plant View, right-click the Maintenance Station OS project and select Plant Hierarchy -> Create/Update Diagnostic Screens.
- Run a full OS Compile.
- Download the PC Station configuration via Station Configuration Editor and download the OS project.
Upgrade to V9.0 SP1 if Data Fails to Load:
- If running base PCS 7 V9.0 without service packs, install PCS 7 V9.0 SP1 to ensure full SNMP driver compatibility.

Verification

Verify switch asset monitoring:
1. Open WinCC Runtime on the Maintenance Station.
2. Navigate to the Network / Diagnostics Overview display.
3. Locate and click on the SCALANCE switch icon.
4. In the resulting diagnostic faceplate, verify that the Order Number (MLFB), Serial Number, and Firmware Version fields are fully populated.
5. Click the Refresh button on the faceplate to confirm instantaneous MIB query updates.
6. Simulate a link disconnect on an unused port and confirm that a Maintenance Station maintenance demand alarm is generated.

Limitations and Operational Precautions

Fieldbus vs. Plant Bus Distinction: Never configure Plant Bus or Terminal Bus switches inside the S7-400 CPU Hardware Configuration; doing so causes bus communication timeouts and invalid station alarms.
SNMP Network Security: SNMPv1 and SNMPv2c transmit community strings in clear text. If cyber-security policies forbid SNMPv2c, ensure switches are isolated within a dedicated management VLAN.
Firmware Compatibility: Switch profiles must correspond to the installed firmware generation. When upgrading switch firmware, verify profile compatibility in the Maintenance Station manual.

Engineer FAQ

Should Plant Bus switches be configured in the CPU Hardware Configuration?

No. Only switches operating as PROFINET IO devices on the fieldbus are configured in CPU HW Config. Plant Bus and Terminal Bus switches are integrated exclusively via the SIMATIC NET SNMP OPC Server on the PC station.

Why does the SCALANCE faceplate display IP and Name but leave MLFB blank?

This occurs when an incorrect SNMP profile (such as generic MIB-II) is assigned in the OPC Server properties, preventing the system from polling Siemens enterprise OIDs, or due to unpatched SNMP scripts in PCS 7 V9.0 base.

Where are the default SCALANCE SNMP profiles located on the ES?

Profiles are located in the SIMATIC NET installation directory under <Drive>:\Program Files (x86)\Siemens\SIMATIC.NET\opc2\snmp\profiles\.

What happens if the switch power fails when monitored via SNMP?

The SIMATIC NET SNMP OPC Server detects the communication timeout (SNMP ping failure) and triggers a 'Network node failure' diagnostic alarm on the Maintenance Station.