Configuring Physical Switch Topology and Plant Bus S7 Connections Across Multiprojects in PCS 7

In SIMATIC PCS 7 multiprojects containing separate Engineering Station (ES) and Automation Station (AS) projects, configuring S7 connections over an Industrial Ethernet plant bus operates at the logical network layer in NetPro, independent of physical switch ports. To model exact physical switch interconnections (such as mapping a CP 1623 port to a SCALANCE XR324-4M switch), engineers must merge project subnets and utilize the STEP 7 Topology Editor rather than the NetPro connection table.

Logical Communication vs. Physical Topology in SIMATIC PCS 7

When designing plant networks in SIMATIC PCS 7, engineers frequently seek to document physical cable runs—such as connecting an Engineering Station's CP 1623 card directly to Port 1 of a SCALANCE XR324-4M switch:
* The Logical Layer (NetPro): In STEP 7 / NetPro, network lines represent logical subnets (Broadcast Domains / IP subnets). An S7 connection between an ES and a CPU 410-5H controller is established by binding both stations to the same logical "Industrial Ethernet" bus line. NetPro does not model physical cable ports or Ethernet patch panels.
* The Physical Layer (Topology Editor): Modeling exact physical port-to-port interconnections (Port 1 on CP 1623 connected to Port 5 on SCALANCE) is managed exclusively in the STEP 7 Topology Editor, which supports PROFINET diagnostic monitoring and device replacement without an engineering programming device.

The Role of NetPro: Subnet Binding and S7 Connection Configuration

To establish communication between an ES (IPC847E with CP 1623) and an AS (CPU 410-5H):
1. In the ES project, open HW Config for the PC Station, insert the CP 1623, and connect its interface to logical subnet PlantBus.
2. In the AS project, open HW Config for the CPU 410-5H, open the integrated PN/IE or CP 443-1 interface, and connect it to logical subnet PlantBus.
3. In NetPro:
* Select the ES WinCC Application or SIMATIC Manager object.
* In the connection table, insert a new S7 Connection.
* Select the CPU 410-5H as the partner station.
* The connection compiles successfully because both interfaces share the common logical broadcast domain, regardless of how many SCALANCE switches lie physically between them.

Modeling Physical Switch Ports via the STEP 7 Topology Editor

If physical port mapping is required for network diagnostic visualization in the PCS 7 Maintenance Station:
1. Open the project containing the SCALANCE switch in HW Config.
2. Select Options -> Topology Editor.
3. In the Graphic View or Table View:
* Locate the SCALANCE XR324-4M switch object.
* Locate the CPU 410-5H integrated PN port.
* Drag a connection line between Port 1 of the CPU and Port 1 of the SCALANCE switch.
* Define cable length and medium (e.g., Cat6 Copper or Fiber Optic).
4. For PC Stations with CP 1623:
* Standard PC communication processors operating in Industrial Ethernet mode (Layer 2 / S7 protocol) do not operate as PROFINET IO devices; therefore, physical port interconnection in the Topology Editor applies primarily to PROFINET IO field devices and CPU ports.

Merging Plant Bus Subnets Across Separate Multiproject Folders

When the ES and AS reside in separate projects within a Multiproject:
1. Open SIMATIC Manager and view the Multiproject tree.
2. Select the top-level Multiproject folder.
3. Select File -> Save As... or navigate to Options -> Multiproject -> Merge / Unmerge Subnets....
4. Select the Industrial Ethernet tab.
5. In the left-hand pane, locate the PlantBus subnet from the ES project and the PlantBus subnet from the AS project.
6. Click Merge. Both logical networks become unified into a single project-wide plant bus.
7. Open NetPro at the multiproject level: the ES and AS now appear on the same continuous green Ethernet line, allowing cross-project S7 connections and SCALANCE switch management.

Verification

In NetPro, select the ES station: confirm that the S7 Connection to CPU 410-5H displays status Configured / Valid.
Execute Network -> Save and Compile: verify that compilation completes with 0 errors.
Open the Topology Editor: confirm that interconnected switch ports display green status lines.
In SIMATIC Manager, execute a test online connection via PLC -> Diagnostic/Setting -> Operating Mode: confirm that the ES communicates with the controller across the SCALANCE switch.

Limitations and Operational Precautions

Do not attempt to force physical topology connections on CP 1623 ports if the card is running in ISO/S7 mode rather than PROFINET IO Controller mode.
Changing IP addresses or subnet masks during subnet merging requires recompiling and downloading hardware configurations to the automation stations during a scheduled plant window.
Verify SCALANCE switch firmware is compatible with the installed STEP 7 hardware catalog.

Engineer FAQ

Can I specify physical switch ports in the NetPro connection table?
No, NetPro configures logical protocol connections; physical port mapping is performed in the Topology Editor.
How do I connect an ES in Project A to an AS in Project B?
Merge their Industrial Ethernet subnets using Options -> Multiproject -> Merge / Unmerge Subnets.
What tool visualizes physical cable lengths and port connections?
The Topology Editor in STEP 7 HW Config / NetPro.
Does CP 1623 require topology configuration to communicate with CPU 410?
No, standard S7 communication requires only matching logical subnets and IP/MAC configurations in NetPro.
What switch model is SCALANCE XR324-4M EEC?
A high-density modular 19-inch rack-mount Layer 2 industrial Ethernet switch supporting up to 24 ports.
Why is physical topology mapping useful in PROFINET networks?
It enables automated device replacement without a programming device and powers the Maintenance Station topology view.
What protocol does CP 1623 use for plant bus communication?
S7 communication over ISO Transport or TCP/IP protocol.
What happens if two merged subnets have conflicting IP address ranges?
NetPro will issue a subnet collision error and block compilation until IP addresses are resolved.
Where in SIMATIC Manager can I open NetPro for the entire multiproject?
Select the multiproject root folder and click the Configure Network (NetPro) icon on the toolbar.
Does S7 communication require configuring PROFINET IO controller roles?
No, S7 communication operates independently of PROFINET IO controller-device relationships.

Technical References

SIMATIC NET SCALANCE X-300 / XR-300 Operating Instructions
SIMATIC PCS 7 PC Configuration and Communication Manual
Siemens Industry Online Support Entry: Modeling Switch Connections in PCS 7 (Entry ID 299692)
SIMATIC STEP 7 V5.6 Network Configuration with NetPro Manual