S7 RedConnect with CP 1623 on PC Stations: Configuration

S7 RedConnect and PC Station Architecture Overview

S7 RedConnect is the Siemens software mechanism that allows a PC station (running WinCC, an OPC server, or a user application) to maintain redundant, fail-safe S7 communication with a fault-tolerant SIMATIC S7-400H station. The redundancy is enforced at the application layer (S7 communication via ISO-on-TCP / RFC1006) and is backed by a hardware pair of CP 443-1 modules on the S7-400H side and a hardware pair of CP 16xx modules on the PC station side. Both communication partners must switch their active channel automatically when a CP, a switch port, a cable, or the partner CPU fails.

A PC station in the SIMATIC NET sense is not a generic office PC. It is a software-defined device whose hardware catalog is loaded into the STEP 7 / TIA Portal project: the index slots of the PC station must contain an OPC server, a WinCC application slot, an S7-REDCONNECT application slot, and the CP 1623 / CP 1628 / CP 1616 cards that physically attach the station to the redundant PROFINET (ISO transport) networks. The inbuilt (motherboard) Ethernet ports of a PC are not represented as objects in the hardware catalog of STEP 7 / TIA Portal and therefore cannot participate in S7 RedConnect.

The S7 RedConnect stack is delivered as part of the SIMATIC NET PC software (SOFTNET-S7 / HARDNET-S7 / S7-REDCONNECT). It exposes a virtual S7 connection that the higher-level application (WinCC channel "S7-REDCONNECT", OPC server channel "S7") binds to, and the stack then maintains two physical S7 connections to CP 443-1 #1 and CP 443-1 #2 simultaneously.

Why Built-in Ethernet Ports Cannot Replace CP 1623

Built-in (on-board) Ethernet controllers of a PC station are visible to the operating system as standard NDIS adapters. They are not enumerated by the SIMATIC NET PC configuration console, cannot be assigned to an "IE General" or "IE CP 16xx" interface in STEP 7 / TIA Portal, and therefore cannot be addressed as a S7 communication endpoint by the S7-REDCONNECT driver. The S7-REDCONNECT stack opens its ISO-on-TCP sockets through the Siemens CP 16xx NDIS proxy driver; it has no path to a generic Intel / Realtek / Broadcom NIC.

This is the technical reason the question of "using the inbuilt Ethernet port as a CP 16xx" cannot be satisfied: STEP 7 / TIA Portal will not allow you to drag a CP 1616/CP 1623/CP 1628 into the same index slot as the on-board NIC, and the SIMATIC NET configuration console will not show the on-board NIC as a configurable interface. The on-board ports can still be used in parallel for:

• Engineering access (STEP 7 online, TIA Portal, WinCC Explorer remote)
• Standard OPC UA / Modbus TCP communication without redundancy
• Office LAN / terminal services traffic

If the PC station is virtualized (VMware ESXi / Hyper-V), neither on-board NICs nor PCI-passthrough CP 1623 cards can be used directly; the certified solution is the S7 RedConnect for VMware package, referenced later in this document. The package ships as product 6GK1704-0HB13-0AA0 on the Siemens product support portal at support.industry.siemens.com/cs/de/en/ps/6GK1704-0HB13-0AA0.

Hardware Requirements: CP 16xx Family Selection

The CP 16xx family consists of PCI / PCI-Express cards that implement PROFINET IO and S7 communication on a Siemens ASIC (ERTEC 200 / ERTEC 400). Each card has its own MAC address and is treated as a slot in the PC station. The following table summarizes the current and legacy SKUs:

For S7 RedConnect against an S7-400H the recommended selection is two identical CP 1623 cards (or two CP 1628 cards if the integrated 2-port switch on the card is needed for line topology). The two cards must be of the same article number and the same firmware version; mixing CP 1612 A2 with CP 1623 is not supported by S7-REDCONNECT because the failover timer constants differ.

On the S7-400H side the redundancy requires two CP 443-1 modules. Recommended variants:

S7-400H and CP 443-1 Redundancy Topology

The typical S7-400H with redundant PC station uses two physically isolated PROFINET segments:

• Segment A: H-CPU 0 → CP 443-1 #A → Industrial Ethernet switch A (managed, e.g., SCALANCE XC-208) → CP 1623 #A on PC station
• Segment B: H-CPU 1 → CP 443-1 #B → Industrial Ethernet switch B → CP 1623 #B on PC station

The two segments must NOT share a switch, must NOT share VLAN trunks, and must use independent IP subnets. The CP 1623 #A gets an IP from subnet A (e.g., 192.168.10.11/24), the CP 1623 #B gets an IP from subnet B (e.g., 192.168.20.11/24). The CP 443-1 #A and CP 443-1 #B each have an IP in their respective subnets, and both H-CPUs share a single logical H-system IP that the S7-REDCONNECT stack uses as the destination.

The three PC stations in the referenced project scenario each require their own pair of CP 1623 cards (or a single pair with a CP 1628 + external switch per station) and their own pair of S7-REDCONNECT licenses if running S7-REDCONNECT to the same S7-400H. If the WinCC servers are redundant among themselves (master / standby / standby), each still needs the CP pair because the redundancy is between PC station and H-system, not between PC stations.

SIMATIC NET PC Software Installation

On every PC station that is to take part in S7 RedConnect, install the following Siemens software stack in the listed order:

1. SIMATIC NET PC software (DVD or download). The current release line is SIMATIC NET PC V20, supported on Windows 10 LTSC 2019 / Windows Server 2019 and Windows 11 / Server 2022. Earlier SIMATIC NET V14 SP1 / V16 are still in maintenance and cover legacy CP 1612.
2. CP 1623 / CP 1628 device driver. The driver is delivered on the SIMATIC NET DVD; do not use the Windows inbox NDIS driver. After installation the CP must appear in Device Manager under "SIMATIC NET" → "CP 1623" with a working device ID (PCI \VEN_110A&DEV_4076 for CP 1623, ERTEC 400 ASIC family).
3. STEP 7 / TIA Portal on the engineering station only. The PC station runtime does not need STEP 7; the project is downloaded to the PC station via the "Configuration Console" of SIMATIC NET, which reads the .pcf or the TIA Portal export.
4. S7-REDCONNECT license key. See the licensing section below.
5. WinCC 7.x or WinCC Unified (if the application layer is WinCC). The WinCC "S7-REDCONNECT" channel driver is part of the WinCC DVD; it must be selected explicitly during installation.

The Configuration Console is launched from Start → Siemens Automation → SIMATIC NET → Configuration Console. Each CP 1623 is assigned a mode:

• Configured mode (recommended for S7-REDCONNECT): configuration is downloaded from STEP 7 / TIA Portal; the CP operates strictly per project.
• PG mode: only for engineering, not usable at runtime.
• Unconfigured / DCP: not allowed for RedConnect.

Configuring the PC Station in STEP 7 / TIA Portal

The PC station is configured as a device in the project tree. In TIA Portal (V17 or later), the typical sequence is:

1. Insert PC station: "Devices & Networks → Add new device → PC station" with type "SIMATIC PC Station" (article 6ES7647-x... or unspecified "SIMATIC PC").
2. Add CP 1623 #1: in the device view, drag "CP Industrial Ethernet → CP 1623 (6GK1162-3AA00) V1.x" into slot 1 (index 1) of the PC station. Set its IP address (e.g., 192.168.10.11) and subnet mask, then connect it to subnet A.
3. Add CP 1623 #2: drag a second CP 1623 into slot 2 (index 2) of the same PC station. This is critical - TIA Portal does not enforce that you add a second CP, but S7-REDCONNECT requires it. Set IP 192.168.20.11 and connect to subnet B.
4. Add OPC server / WinCC application: drag "OPC server" or "WinCC RT" into slot 3 / 4 of the PC station.
5. Add S7-REDCONNECT: in the catalog under "Communication → S7-REDCONNECT" drag the entry into the application slot. This adds a virtual connection that points to the H-system IP.
6. Insert S7 connection to the H-station: in "Connections" tab of the OPC / WinCC application, insert a "S7 connection" with partner = the H-station IP. The S7-REDCONNECT driver will then replicate this single connection onto both CP 1623 cards.
7. Compile and download: right-click the PC station → "Compile and download to target device" or, if using Configuration Console on the PC itself, export the PC station configuration to a .pcf file and load it via "Configuration Console → Set PC Station".

For the CP 1616 family (older deployments), Siemens also documents the slot assignment procedure; see the manual entry at SIMATIC NET PC - Using the CP 1616 as a PROFINET IO controller which confirms that CP 1616 must be inserted into slot 1 of the PC station hardware catalog.

Licensing S7 RedConnect

S7-REDCONNECT is licensed per PC station (not per CP, not per connection). A PC station that runs S7-REDCONNECT on its CP pair to one H-station needs exactly one license of the appropriate SKU:

The VMware SKU (6GK1704-0HB13-0AA0) is a software bundle that includes the VM-host-side driver and a per-VM token. Each VM running WinCC or OPC server with S7-REDCONNECT needs its own activation key (transferred to the Automation License Manager on the guest VM).

If the PC station is bare metal with two physical CP 1623 cards, the simpler SKU 6GK1704-0HB03-0AA0 is sufficient. The license is bound to the SIMATIC PC station name (the "PC station name" field in STEP 7 / TIA Portal) and the Microsoft Windows SID of the operating system. Re-imaging the PC requires re-activation via the Web License Manager or a manual transfer with the Automation License Manager.

Network Topology and IP Planning

Use a dedicated IP plan for the redundant segments to avoid routing problems. A conservative example for a single H-station with three PC stations:

The two segments must be physically separated. They must not be bridged by a Layer-2 device. They may share the same IP class only if the management network is on yet a third subnet and the SCALANCE switches are configured as routers (which they are by default if no bridge is configured). In typical Siemens reference architectures a single SCALANCE XC-208 is used per segment in ring mode with HRP or standalone; do not place both segments on the same switch.

Commissioning and Verification Procedure

Follow this sequence once the hardware and software are installed:

1. Verify CP enumeration: in Device Manager on the PC station, confirm two CP 1623 devices with no warning icons. Both must show a "SIMATIC NET Configuration" entry under the device properties.
2. Verify PC station name: the name set in STEP 7 / TIA Portal must match the Windows "Computer Name" or the S7-REDCONNECT stack will not pick up the configuration. Set it via "Configuration Console → Station → Station Name".
3. Verify IP address: ping CP 443-1 #A from the PC station via CP 1623 #A, and CP 443-1 #B via CP 1623 #B. The ping must use the source address of the corresponding CP - Windows will normally use the wrong interface. Use ping -S 192.168.10.11 192.168.10.1 from an admin cmd to force source.
4. Start the S7-REDCONNECT service: open "Services" (services.msc) and verify "SIMATIC NET S7-REDCONNECT" is set to "Automatic" and running. Start it if stopped.
5. Start the OPC server / WinCC: the runtime will log "S7-REDCONNECT: primary connection established via CP 1623 #1" and "secondary connection established via CP 1623 #2" within ~5 s of startup if all is well.
6. Verify in WinCC channel diagnostics: "WinCC Explorer → Tools → Channel Diagnosis → S7-REDCONNECT" must show two green "OK" entries. If only one shows OK the secondary CP is not bound.
7. Failover test: disconnect the Ethernet cable on CP 1623 #A. Within 1-3 s WinCC must continue without losing tag updates. Re-connect, and within 1-3 s the primary channel must restore. Repeat for CP 1623 #B and for the CP 443-1 modules.
8. CPU switchover test: in STEP 7 / TIA Portal, force an H-system switchover via "Online → H-System → Switchover". All WinCC connections must stay green and no data loss must be visible in the archive.
9. Document: save the failover logs (PNIO trace, S7-REDCONNECT log) for the commissioning report.

Verification commands (PC station)

:: Verify CP 1623 binding
set_pn_io -list

:: Show S7-REDCONNECT active connection
C:\Program Files\Siemens\Automation\SIMATIC_NET\opc2\bin\s7rccfg.exe -status

:: Trace S7-REDCONNECT events (requires SNVCT trace permission)
snvltrace -d S7REDCONNECT -l 6 -o C:\logs\s7redconnect.trc

Diagnostic and Troubleshooting Matrix

Frequently Asked Questions