PCIe Slot Compatibility and Dual CP 1623 Communications Processor Installation in PCS 7

Yes, installing two SIMATIC NET CP 1623 communications processors (6GK1162-3AA00) across different PCIe slot types—such as one card in a PCIe x1 slot and the second card in a PCIe x4 or PCIe x16 slot—is fully supported and technically compliant. Under the PCI Express specification, PCIe slots are backward and upward compatible, allowing a PCIe x1 physical lane card to operate seamlessly in larger mechanical slots (x4, x8, x16) without signal degradation or performance loss. In SIMATIC PCS 7, both CP 1623 cards will be recognized independently by SIMATIC NET PC Software and assigned distinct component indices in the Station Configuration Editor for redundant plant bus connectivity.

Executive Summary

High-availability SIMATIC PCS 7 architectures frequently require Industrial Ethernet communications processors—such as the SIMATIC NET CP 1623—to handle high-performance, deterministic communications over optical or electrical plant buses to redundant S7-400H controllers. When configuring custom industrial PCs (IPCs) or commercial server workstations for Engineering Stations (ES) or WinCC OS Servers, motherboard backplanes rarely provide multiple identical PCIe x1 slots. Instead, motherboards typically feature a mix of PCIe x1, PCIe x4, and PCIe x16 slots. Hardware engineers frequently question whether installing two CP 1623 cards into mismatched slot types introduces communication instability or driver conflicts. This article confirms PCIe architectural compatibility and details dual CP 1623 configuration in SIMATIC NET.

Architecture and Fundamental Mechanics

The physical, electrical, and software mechanics of the CP 1623 in multi-slot architectures are governed by PCI-SIG and SIMATIC NET standards:

PCI Express Up-Plugging Specification: The PCI Express (PCIe) standard enforces strict mechanical and electrical compatibility. The specification explicitly mandates 'up-plugging'—the ability of any smaller lane device (e.g., x1) to fit and operate inside a larger mechanical slot (x4, x8, x16). A PCIe x1 card only connects to the single lane clock, ground, and data differential pairs; the host motherboard PCIe root complex automatically negotiates the link width down to x1 mode, delivering full bidirectional bandwidth (500 MB/s for Gen2) without electrical damage or timing jitter.
The Hardware Architecture of CP 1623: The CP 1623 (MLFB 6GK1162-3AA00) is an intelligent PCI Express x1 communications processor equipped with an onboard microprocessor and dual RJ45 Industrial Ethernet ports with an integrated 2-port switch. It offloads ISO transport protocols and S7 communication stacks directly to onboard hardware, freeing host PC CPU resources.
Dual-Card SIMATIC NET Driver Handling: In SIMATIC NET PC Software, each physical CP 1623 card operates as an independent PCIe device with unique hardware IRQs and base I/O memory addresses. The driver assigns device names sequentially: CP1623_1 and CP1623_2.
Station Configuration Editor Integration: In the Windows Station Configuration Editor, the two cards are assigned to separate slots (e.g., Index 2 for Plant Bus Redundant Path A, and Index 3 for Plant Bus Redundant Path B). In STEP 7 HW Config and NetPro, Named Connections and S7-REDCONNECT bind to both CPs, enabling bumpless communication failover across redundant subnets.

Step-by-Step Implementation Procedure

Execute the physical installation and software configuration using the following procedure:

Physical Card Installation:
- Power down the industrial PC and disconnect power cables.
- Insert the first CP 1623 into the available PCIe x1 slot.
- Insert the second CP 1623 into the available PCIe x4 or PCIe x16 slot.
- Secure both cards firmly with chassis screws to ensure proper grounding and shielding.
- Connect the plant bus Industrial Ethernet cables (Subnet 1 to Card 1, Subnet 2 to Card 2).
Verify Device Recognition in Windows:
- Power on the PC and boot into Windows.
- Open Windows Device Manager -> expand SIMATIC NET (or Network Adapters).
- Confirm that two distinct entries appear: SIMATIC NET CP 1623 #1 and SIMATIC NET CP 1623 #2, with zero warning triangles.
Configure Station Configuration Editor (SCE):
- Open the Station Configuration Editor from the taskbar tray.
- Click Add on Index 2 -> select CP 1623 -> name it CP1623_1.
- Click Add on Index 3 -> select CP 1623 -> name it CP1623_2.
- Confirm that both components transition to status RUN (green).
Configure HW Config and NetPro on the ES:
- In SIMATIC Manager Component View, open HW Config for the PC Station.
- Add the second CP 1623 from the hardware catalog into Index 3.
- Assign IP addresses and MAC addresses matching the physical cards.
- In NetPro, configure fault-tolerant S7 connections (S7-REDCONNECT) utilizing both CP 1623 interfaces.
- Save, compile, and download the station configuration to the local PC Station.

Verification

Verify dual CP 1623 operation and communication redundancy:

Communication Processor Diagnostics: Open Communication Settings (or SIMATIC NET -> Diagnostics). Verify that both CP1623_1 and CP1623_2 display link status 'Connected' at 100 Mbps or 1 Gbps Full Duplex.
WinCC Channel Diagnosis: Launch WinCC Runtime and open WinCCChannelDiagnosis.exe. Verify that under Named Connections, both communication paths to the redundant AS controllers show status OK.
Physical Cable Pull Redundancy Test: Disconnect the Ethernet cable from the first CP 1623 (in the PCIe x1 slot). Observe WinCC runtime process values. Confirm that process graphics continue updating seamlessly via the second CP 1623 (in the PCIe x4/x16 slot) without tag dropouts.

Limitations and Operational Precautions

Ensure the motherboard BIOS settings do not restrict multi-lane PCIe slots to GPU-only operating modes; some consumer motherboards disable PCIe x16 slots if a non-graphics card is detected, though industrial motherboards (e.g., Siemens SIMATIC IPCs) fully support general PCIe peripherals across all slots. Note that the CP 1623 requires SIMATIC NET HARDNET communication software licenses (e.g., HARDNET-IE S7-REDCONNECT) to operate fault-tolerant connections. Final hardware and license procurement must be validated with an authorized Siemens distributor or the Siemens Industry Mall.

Engineer FAQ

Can a PCIe x1 card damage a PCIe x16 slot?

No. The PCI Express specification explicitly requires slot backward and forward compatibility. The motherboard automatically powers and routes only the single lane used by the x1 card.

Does installing CP 1623 in a PCIe x16 slot cause performance bottlenecks?

No. The CP 1623 communicates at PCIe Gen 1.1 / Gen 2 x1 speed (up to 500 MB/s), which far exceeds the maximum data throughput of dual 1 Gbps Industrial Ethernet ports.

Why install two CP 1623 cards in an Engineering Station or OS Server?

Installing two CP 1623 cards provides physical network redundancy for S7-400H systems, ensuring that a cable break or switch failure on one plant bus subnet does not interrupt supervisory monitoring or engineering downloads.

Does CP 1623 support integrated switching?

Yes. Each CP 1623 features two RJ45 ports with an integrated 2-port switch, allowing daisy-chain line topologies without external switches.

What is the difference between CP 1623 and CP 1613?

The CP 1613 was an older legacy PCI card. The CP 1623 is its modern PCI Express equivalent, delivering identical software functionality with higher hardware processing speed and PCIe compatibility.