Adding a Second WinCC Workstation to S7-300 Single-User System

Architecture Overview

Single-user WinCC V7 SCADA stations communicating with a SIMATIC S7-300 CPU over Industrial Ethernet use the SIMATIC NET Named Connection transport rather than raw ISO-on-TCP or TCP/IP. The CP 343-1 Lean (6GK7 343-1CX10-0XE0) on the S7-300 rack terminates the Ethernet connection; the WinCC side terminates the connection on the PC Station's IE General application. When the project is integrated with STEP 7, the connection is configured once in NetPro, downloaded to the PLC, and compiled to the WinCC Tag Management. The single-user design implicitly assumes one PC Station endpoint per connection.

Adding a second workstation (WS#2) requires either:

1. A second PC Station in NetPro with a unique IP, its own S7 connection, and a separate Named Connection in WinCC on WS#2, or
2. Conversion of WS#1 to a Multi-User server and WS#2 added as a WinCC client (no second S7 connection needed).

Path (1) keeps the project as single-user on each machine and is the cleanest fit when the user wants two independent operator stations each holding their own WinCC project copy. Path (2) introduces a server/client hierarchy with shared archives, alarms, and tags.

Prerequisites

CP 343-1 Lean Configuration Review

The CP 343-1 Lean is an Ethernet communications processor for the S7-300 with a single RJ45 port. It supports PG/OP communication, S7 communication, ISO transport, and TCP transport. The cited version 6GK7 343-1CX10-0XE0 ships with firmware V2.2 which is appropriate for SIMATIC NET V12/V13 era stacks. The CP's IP address is assigned either via STEP 7 (HW Config → CP 343-1 Lean → Properties → Ethernet Interface) or via the CP's web interface; STEP 7 is preferred for reproducible configurations.

Confirm the following in HW Config before adding a second PC Station:

• CP is set to IP Protocol (not MAC-only)
• The CP's IP belongs to the same subnet as both WS#1 and WS#2
• Use router is disabled (single subnet)
• Connection resources are set to PG, OP, and S7 communication with the maximum number of OP connections (default 16 on a CP 343-1 Lean is usually sufficient for two operator stations)

Creating a Second PC Station in NetPro

Open the STEP 7 project that contains the S7-300 station and the existing WS#1 PC Station. The S7-300 station in NetPro must contain an S7 connection to WS#1 with the Active connection establishment checkbox configured according to your original commissioning.

1. In NetPro right-click the project, choose Insert New Object → SIMATIC PC Station.
2. Rename the new PC Station to the computer name of WS#2 (the name reported by ipconfig /all or System Properties on WS#2).
3. Open HW Config of the new PC Station and insert a virtual slot 1 IE General module (Application: WinCC → IE General). The IE General represents the IE communication access point of Simatic Net on WS#2.
4. Set the IP address and subnet mask of the IE General to match WS#2's network interface.
5. Save and compile HW Config (Station → Save and Compile).
6. In NetPro select the S7-300 station and insert a new S7 connection to the new PC Station. Use a unique local ID (for example 2; the existing WS#1 connection is typically ID 1).
7. Confirm the partner station, partner interface (the IE General on WS#2), and partner rack/slot 0 are correctly populated.
8. Right-click the new S7 connection → Object Properties → Connection and verify Active connection establishment matches the original WS#1 configuration.
9. Save and compile NetPro. The PC Station's Configuration tab is now populated with an S7 connection.

OS Connection Count on the S7-300 CPU

The S7-300 CPU has a configurable parameter Number of OP connections (sometimes displayed as OS connections). This value defines how many simultaneous operator-station connections the CPU will accept. The default on most S7-300 CPUs is 1 or 2.

Procedure:

1. Open HW Config of the S7-300 station.
2. Select the CPU → Object Properties → Communication.
3. Increase the Number of OP connections field to at least 2. If a WinCC Flexible (or WinCC Comfort) HMI panel is also connected, add it to the count. For two WinCC V7 stations and one panel, set the value to 3.
4. Save, compile, and download the HW Config to the CPU. This will trigger a CPU STOP → START cycle.

WinCC Tag Management on WS#2

The WinCC project that was copied to WS#2 still references the Named Connection transport on the Simatic S7 Protocol Suite. The Named Connection on WS#2 must point to a different S7 connection from the original — namely the new connection created in NetPro with the new PC Station.

1. On WS#2 open the copied WinCC project in WinCC Explorer.
2. Right-click Tag Management → Simatic S7 Protocol Suite → Named Connections and select System Parameter → Logical Device Names (or use the Connection list).
3. For each existing logical connection, set the Connection Name / Application Name to the S7 connection created in NetPro for WS#2 (i.e., the connection targeted at the new PC Station).
4. If you want a strict 1:1 mirror of WS#1's tag structure with the same connection name, you must re-link each connection to the new NetPro S7 connection local ID. The local IDs on the PLC side are written to S7con in the WinCC project directory under \<WinCC project>\S7Con.
5. Save the WinCC project.

Station Configuration Editor on WS#2

The Simatic Net Station Configuration Editor (Start → Simatic → SIMATIC NET → Configuration Console → Station Configuration Editor) is the runtime on the PC that hosts the IE General application for the PC Station. NetPro's PC Station download writes the configuration to this local station.

1. On WS#2, open the Station Configuration Editor. The PC Station name must equal the STEP 7 PC Station object name (i.e., the computer name of WS#2).
2. From NetPro, select the new PC Station → Download to Target Station. The component WinCC Application is detected automatically. The S7 connection becomes active once the IE General module is online and the connection partner is reachable.
3. If the IE General appears with a red status, open Configuration Console and verify the assigned network interface is correct (e.g., the system's primary NIC, not a virtual Hyper-V/TAP adapter).

PG/PC Interface (Set PG/PC Interface)

On WS#2, open the Set PG/PC Interface control panel and select the access point used by the WinCC Named Connection. The typical setting for a Named Connection is:

• Access point of application: S7ONLINE (the default for STEP 7 and WinCC S7 connections)
• Interface parameterization: PC Internal (local) when using Named Connections routed through Simatic Net, TCP/IP → <NIC> when using TCP/IP transport

For Named Connections the access point is typically S7ONLINE set to PC Internal because the actual transport is handed off to the IE General application inside the Simatic Net station. Switching this to TCP/IP → <NIC> would bypass the station and is therefore incorrect for the S7-300/CP 343-1 Lean Named Connection topology.

Multi-User Project Alternative

If both workstations need to share the same picture set, archives, and alarms, the cleanest Siemens-supported design is a Multi-User project rather than two independent single-user projects.

1. Open the WinCC Explorer on WS#1, select Project → Properties, switch the project type from Single-User Project to Multi-User Project.
2. Recompile the project; WinCC will internally split it into a server portion and a client stub.
3. Install a WinCC Server license (RT 128 or larger) on WS#1.
4. On WS#2, install WinCC with a WinCC Client license and configure the client to point to WS#1's server (project path: \\WS#1\<projectname>).
5. Match Windows user accounts and passwords on both machines (the same Windows user must exist on both) and ensure the user has write access to the project directory — WinCC clients write back the local picture cache.

This approach consumes a single OPC/S7 connection to the PLC and avoids the OS connection count problem entirely. The trade-off is that WS#2 depends on WS#1 being online. If both stations must operate independently during a server outage, the two single-user PC Stations design (Path 1) is the correct choice.

Licensing Considerations

Step-by-Step Commissioning

1. Verify network reachability: from WS#2 ping <CP 343-1 Lean IP>. Expected reply <1 ms on a switched Ethernet segment.
2. Open STEP 7 on WS#2 (or from WS#1 with the project on a shared drive). Confirm the new PC Station's name matches WS#2's computer name.
3. Download the new PC Station configuration to the Station Configuration Editor on WS#2.
4. In NetPro download the PLC station's PC connections (download to Connections Only to avoid an unnecessary full download).
5. Open HW Config of the CPU, raise the OP connection count, and download. CPU will STOP → RUN.
6. On WS#2 launch WinCC Runtime. The activation screen should report a single Named Connection Online.
7. Toggle a bit in the PLC (or use a forcing table with care) and verify the value updates on both WS#1 and WS#2.

Verification Checklist

Troubleshooting Matrix

Field-Proven Caveats

Two common pitfalls not covered in vendor quick-start guides:

• The Named Connection name in WinCC is a symbolic label, not a network endpoint. Renaming a WinCC connection does not change which PLC connection is used; the binding to the STEP 7 S7 connection local ID is the only thing that matters.
• When using Industrial Ethernet (II) as the WinCC transport, the connection uses ISO transport directly and bypasses the Station Configuration Editor. Mixing the two transport types inside one project is a known source of intermittent disconnects — pick one transport per project and stick to it.

FAQ