Configuring Dual CP 1623 Redundant Network Adapter Switchover in SIMATIC PCS 7

In SIMATIC PCS 7, installing two SIMATIC NET CP 1623 PCI Express cards (6GK1162-3AA00) in an OS Server or Engineering Station does not provide automatic hardware failover by default. For the Plant Bus, automatic bumpless switchover requires configuring a Fault-Tolerant S7 Connection (Named Connection) utilizing SIMATIC NET S7-RedConnect in NetPro, binding both CP 1623 cards across redundant ring subnets. For the Terminal Bus, automatic adapter redundancy requires configuring Network Interface Card (NIC) teaming (e.g. Intel PROSet Adapter Fault Tolerance) within the Windows operating system.

Plant Bus vs. Terminal Bus Redundancy Architecture

In SIMATIC PCS 7 architectures, network communications are strictly divided into two physically or logically isolated networks:
1. Terminal Bus: Connects OS Servers, Engineering Stations, OS Clients, and domain controllers. It carries WinCC server-client traffic, historical data replication, and project engineering downloads.
2. Plant Bus: Connects OS Servers and Engineering Stations to the Automation Stations (S7-400H or CPU 410-5H). It handles cyclic and event-driven process data, alarms (ALARM_8P), and operator setpoint demands.

When an industrial workstation (such as a SIMATIC IPC647D or IPC847D) is equipped with two SIMATIC NET CP 1623 communications processors (6GK1162-3AA00), engineers must understand that Windows cannot magically balance or failover Siemens S7 industrial protocol traffic across two raw network interfaces without explicit protocol-level configuration.

Why Dual CP 1623 Cards Require S7-RedConnect on the Plant Bus

On the Industrial Ethernet Plant Bus, communication between WinCC OS and S7-400H controllers is governed by ISO Transport (Layer 4) or ISO-on-TCP (RFC 1006).

If CP 1623 #1 suffers a hardware failure, broken fiber cable, or switch port failure, automatic failover to CP 1623 #2 requires SIMATIC NET S7-RedConnect:
* In NetPro, the connection between the WinCC Application and the S7-400H CPU is created as a Fault-Tolerant S7 Connection (Named Connection).
* NetPro assigns multiple independent physical communication paths (Path A over CP 1623 #1, Path B over CP 1623 #2).
* S7-RedConnect monitors the health of all physical sub-paths simultaneously.
* If the primary path drops, S7-RedConnect switches communication to the secondary CP 1623 in under 100 milliseconds, completely bumplessly and transparently to WinCC tag management.

Terminal Bus Teaming vs. Plant Bus Multi-Homing

Attempting to use standard Windows Network Adapter Teaming on the Plant Bus with CP 1623 cards is unsupported:
* Terminal Bus: Uses standard commercial TCP/IP traffic. Redundancy is achieved using operating system adapter teaming (Intel PROSet Adapter Fault Tolerance - AFT) or Switch Fault Tolerance (SFT). Teaming binds two physical ports into a single virtual MAC and IP address.
* Plant Bus: The CP 1623 contains its own onboard communication coprocessor running Siemens-proprietary firmware. Windows teaming software cannot bind intelligent coprocessor cards. Redundancy on the plant bus must be handled exclusively through NetPro fault-tolerant routing and S7-RedConnect.

Network Adapter Redundancy Mechanism Matrix

The following matrix compares plant bus and terminal bus redundancy methods for dual network cards:

Parameter / FeaturePlant Bus (Dual CP 1623)Terminal Bus (Standard Dual NICs)Redundancy ManagementNetPro S7-RedConnect ProtocolWindows NIC Teaming (Intel PROSet AFT)Failover Time< 100 ms (Bumpless)1 to 3 secondsAddressing MethodIndependent MAC/IP per CP cardShared Virtual MAC and IP addressSwitch ConfigurationRedundant SCALANCE Ring (HRP/MRP)Standard Spanning Tree / TrunkingWinCC Impact on FailureZero (Tags continue live updates)Momentary client reconnectionRequired Software LicenseS7-RedConnect LicenseIncluded with OS / NIC driver

Step-by-Step Configuration Workflow in NetPro and Station Configurator

To configure automatic failover across two CP 1623 cards on the Plant Bus:
1. Configure the PC Station in HW Config:
- In SIMATIC Manager, open the OS Server or ES PC Station in HW Config.
- Insert CP 1623 into an available virtual slot (e.g. Slot 1). Assign it to Subnet 1 (Plant Bus A) with its physical MAC and IP address.
- Insert the second CP 1623 into another slot (e.g. Slot 2). Assign it to Subnet 2 (Plant Bus B) with distinct MAC and IP addresses.
2. Configure Station Configuration Editor:
- On the physical PC, open the Station Configuration Editor.
- Add both CP 1623 cards into the exact slot positions defined in HW Config.
- Ensure both cards report RUN / OK.
3. Configure Fault-Tolerant Connections in NetPro:
- Open NetPro. Select the WinCC Application in the OS PC station.
- Insert a New Connection: Set Connection Partner to the S7-400H CPU, and Connection Type to Fault-Tolerant S7 Connection.
- In Connection Properties, select Named Connection.
- Under the Route Configuration tab, verify that both CP 1623 cards (Slot 1 and Slot 2) are selected as active local interfaces.
4. Compile and Download:
- Save and Compile NetPro (Check and Compile All).
- Download network connections to the PC Station and the S7-400H controller.
5. Verify Runtime Redundancy:
- Activate WinCC Runtime. Open WinCC Channel Diagnosis: Under Named Connections, verify that two or four sub-paths are listed in state Established / Ready.

Verification

Verify that adapter failover executes cleanly without tag disruption:
1. Open WinCC Runtime on the OS Server: Display a high-speed dynamic trend curve (e.g. flow transmitter updating every 500 ms).
2. Physically disconnect the network cable from Port 1 of CP 1623 #1.
3. Observe WinCC process graphics:
- Confirm that trend curves and process values continue updating without freezing or showing disconnected states (???).
- Confirm no connection-lost alarms appear in WinCC Alarm Logging.
4. Open WinCC Channel Diagnosis: Verify that Sub-Path 1 transitions to disconnected, while Sub-Path 2 remains active and carrying communication.
5. Reconnect the cable: Confirm Sub-Path 1 returns to healthy standby/active status.

Limitations and Operational Precautions

Both CP 1623 cards must connect to physically separate network switches or isolated VLAN rings to ensure switch faults do not take down both adapters simultaneously.
S7-RedConnect requires compatible communications processors in the S7-400 controller (e.g. dual CP 443-1 modules or integrated PROFINET ports on CPU 410-5H).
Commercial licensing note: S7-RedConnect requires software licensing on the PC station; consult an authorized Siemens distributor to confirm procurement schedules.

Engineer FAQ

Can I use two CP 1623 cards without S7-RedConnect?

You can install two CP 1623 cards, but without S7-RedConnect, WinCC can only bind to one card at a time. If that card fails, the system will not switch to the second card automatically; manual reconfiguration in Station Configuration Editor would be required.

Do the two CP 1623 cards need to be on the same IP subnet?

No. Best practice places Plant Bus A and Plant Bus B on separate IP subnets (e.g. 192.168.1.x for CP 1 and 192.168.2.x for CP 2) to ensure strict deterministic routing.

Can CP 1623 and CP 1613 A2 be paired in a redundant configuration?

Yes, provided both cards are installed on an operating system that supports both drivers (such as Windows 7 32-bit). However, mixing PCIe and legacy PCI cards is generally discouraged.