WinCC 7 to S7-400H Redundant Ethernet with CP 1613 / CP 1623

1. Overview: Redundant WinCC 7 ↔ S7-400H Architectures

Connecting a SIMATIC WinCC V7 operator station (OS) to a SIMATIC S7-400H fault-tolerant PLC over Industrial Ethernet requires a Siemens-approved network interface and either the S7-REDCONNECT software layer (for fully transparent link redundancy) or a software redundancy pattern built on the application side. The single most common H-system target is the CPU 414-4H or CPU 417-4H with two synchronized H-CPUs and one or two CP 443-1 on the plant side, mirrored on the PC side by one or two CP 1613 (PCI/PCI-X) or CP 1623 (PCIe) communications processors.

Redundancy on the plant LAN is mandatory for any 400H OS that participates in high-availability or safety-relevant process control. Without it, a single CP, cable, or switch port failure forces the operator station into a communication fault that masks the real process state. The Siemens solution provides seamless switchover in the second range (typical < 1 s) once redundancy is configured, with no scripting and no WinCC-side polling of CPU status.

This article covers the canonical configuration for:

• CP 414-4H / CP 417-4H with two CP 443-1 EX30 (or higher) on rack 0 and rack 1.
• WinCC V7.0 / V7.2 / V7.3 / V7.4 SP1 running on Windows XP Professional 32-bit, Windows Server 2003 32-bit, or Windows 7 Ultimate / Business 32-bit.
• One CP 1613 per CPU (two cards per OS) for full link + CPU redundancy, or a single CP 1623 used as a 2-port switch with the same IP address, or one CP 1613 with S7-REDCONNECT for CPU-level redundancy only.

Reference: SIMATIC S7-400H Fault-Tolerant Systems System Manual, WinCC V7 Communication Manual.

2. Prerequisites

3. Hardware Comparison: CP 1613 vs CP 1623

Operating insight: the CP 1623 is registered in the PC station as a single communications processor with one IP, even though two physical cables land on the back of the card. From STEP 7 NetPro and from WinCC you configure one S7 connection — the OS has only one transport address. The two RJ45 sockets exist purely to give the upstream network an alternate physical path; S7-REDCONNECT handles the link layer on the PC side the same way it does for a single-port CP 1613.

4. Installation Sequence

1. Power down the PC, install the CP 1613 / CP 1623 in a free slot, do not connect any cables yet.
2. Boot Windows, log in with administrator rights.
3. Install SIMATIC NET PC software from the latest SIMATIC NET DVD (the S7-1613 and S7-REDCONNECT drivers are bundled).
4. When the hardware wizard detects the new CP, point it to the INF file shipped on the SIMATIC NET CD — do not let Windows install the in-box Realtek / Intel driver.
5. Reboot, open Station Configuration Editor (Start → SIMATIC → SIMATIC NET → Station Configuration Editor). The CP 1613 / CP 1623 must appear in slot 1 (or whichever index matches NetPro).
6. Assign the card an IP address, subnet mask, and (if used) router. Example for CPU 0:

   CP 1613 / CP 1623 IP : 192.168.0.10
   Subnet mask          : 255.255.255.0
   Router (optional)    : 192.168.0.1

7. Repeat for the second NIC (if used) with a second IP, e.g. 192.168.1.10 — each CP must sit on a different IP subnet so that the 400H sync is not confused by duplicate address detection.
8. Close the Station Configuration Editor; the XDB file in C:\Program Files\Siemens\Automation\Simatic.NET\... is the file WinCC will later reference.

5. NetPro Configuration: Fault-Tolerant S7 Connection

The 400H side of the link is configured in STEP 7 → NetPro inside the S7-400H station. The OS side is configured in STEP 7 → NetPro inside the PC station that lives in the same STEP 7 project. The connection object is a S7 connection with the attribute "fault-tolerant" set.

1. Open the STEP 7 project that contains both the S7-400H station and the PC station.
2. In the PC station, insert a CP 1613 or CP 1623 in the same slot that the Station Configuration Editor is using.
3. Right-click the CP → Insert New Connection → select the partner S7-400H and partner interface CP 443-1 (rack 0 / rack 1).
4. In the connection properties dialog, set:
   • Type: S7 connection
   • Active / Passive: Active (the OS establishes the connection).
   • Fault-tolerant connection: ✓ enabled
   • Connection name: e.g. OS_to_AS_H1
5. For full link redundancy (one OS, two CP 1613 cards, one per CPU), repeat the connection for the second PC CP, and the second S7-400H CP 443-1. WinCC will load-balance tag requests across both connections.
6. Save and Compile OS (Station → Compile). The compiler regenerates the XDB file used by the Station Configuration Editor.
7. Download the PC station configuration to the OS — NetPro will call the Station Configuration Editor and write the XDB.

Reference: S7-REDCONNECT for Industrial Ethernet Manual, section 5.3 "Configuring fault-tolerant S7 connections in NetPro".

5.1 Resulting Object Graph

After step 5, the XDB contains two application endpoints (one per CP) and one logical S7 fault-tolerant connection that owns both. WinCC imports the XDB through the SIMATIC NET Shell and sees a single logical S7 channel whose transport address is the primary CP's IP. REDCONNECT then keeps that channel alive by failing over to the secondary CP within 1–3 switchover cycles (typical < 1 s, worst case 3 s) when the active path drops.

6. WinCC 7 Project Configuration

1. Open the WinCC Explorer. Select Tag Management → SIMATIC S7 PROTOCOL SUITE → TCP/IP.
2. Right-click TCP/IP → System Parameters → Unit. The driver reads the XDB and lists the fault-tolerant connection under Logical Device Name (e.g. S7-REDCONNECT1).
3. Create tag references using the connection name. The tag address format is the standard S7 area addressing, e.g. DB120.DBD0 for a REAL or MW100 for a WORD.
4. In Computer → Properties → Startup, enable "Activate WinCC runtime" and confirm that the S7-REDCONNECT service is set to Automatic.
5. Activate the project. Open the WinCC Channel Diagnosis applet — the S7 connection must show state "OK / RED" with both physical paths reported as active.

Reference: WinCC V7 Communication Manual, chapter 7 "S7-REDCONNECT integration".

7. Redundancy Behavior and Switchover Diagnostics

Three classes of failure must be handled:

The S7-REDCONNECT service writes a diagnostic log to %ProgramFiles%\Siemens\Automation\Simatic.NET\S7REDLOG. Inspect s7redlog.txt to confirm:

• STATE = ACTIVE / STANDBY for both physical connections.
• SWITCHOVER COMPLETE events with timestamps bracketing the network incident.
• No ERROR 0x80xx entries (see REDCONNECT manual for the hex error table).

8. Alternative: Software Redundancy (No S7-REDCONNECT)

If licensing or driver availability makes S7-REDCONNECT impractical, the 400H can still be reached from a single CP 1613 / CP 1623 by configuring two separate S7 connections in NetPro — one to the rack-0 CP 443-1, one to the rack-1 CP 443-1 — and adding a WinCC C-script that monitors the connection status and selects the live one for tag updates. This pattern is called software redundancy:

1. NetPro: create two passive S7 connections, one per H-CPU CP 443-1, both pointing to the same PC CP.
2. WinCC: add both connections under Tag Management → TCP/IP.
3. For each tag, use a C-action that returns the value of the active connection based on the WinCC internal variable @S7_Connection_State.
4. On a connection-down event, force Activate on the standby and re-evaluate the tag every 500 ms until it comes back up.

9. Verification & Commissioning Checklist

1. Both CPUs in the 400H are in RUN with H-sync OK (no SF on the CPU display).
2. CP 443-1 on each rack has link LED on the assigned Ethernet port.
3. PC CP 1613 / CP 1623 shows active in the Station Configuration Editor.
4. NetPro download completed with the message "Configuration loaded successfully".
5. WinCC Channel Diagnosis shows the S7 connection in state OK / RED with two physical paths active.
6. Force the test: pull the Ethernet cable from CP 0 of the active CPU. Within < 1 s the WinCC channel switches to CP 1; no operator tag goes red.
7. Pull the Ethernet cable from the active PC CP 1613. WinCC channel stays OK; check s7redlog.txt for SWITCHOVER COMPLETE.
8. Stop the active CPU (STOP toggle on the CPU). After < 1 s the standby CPU takes over and WinCC keeps the process picture up to date.
9. Restore every fault. Confirm WinCC shows zero unacknowledged alarms related to the S7 channel.

10. Troubleshooting Matrix

Reference for hex error codes: S7-REDCONNECT for Industrial Ethernet Manual, appendix A.

11. Edge Cases and Field Notes

• Single CP 1623, two AS, no OS: because the CP 1623 forwards frames at wire speed when the PC is off, you can use it as a small unmanaged switch between two S7-400H stations for CPU-to-CPU communication (e.g. shared DB on rack 0 read by rack 1). This is documented in the CP 1623 manual section 4.5.
• Two CP 1613 in one OS, one CP 443-1 per H-CPU: this is the canonical "full redundancy" setup. WinCC sees one logical channel but two physical transports; the OS can lose either NIC and the HMI stays live.
• One CP 1613, no REDCONNECT, no script: works for visualization only when the OS can tolerate a 3–5 s freeze on the first failure — not acceptable for control rooms.
• Mixing CP 1613 and CP 1623 on the same OS: supported. The XDB simply lists two different card types; REDCONNECT treats them as two independent transports.
• Firewall on the OS: Windows Firewall must allow the SIMATIC NET services (default install adds rules). On hardened stations, open UDP/TCP 102 (S7 communication) explicitly.
• Time sync: 400H uses SIMATIC time; on switchover the timestamp can step. Run WinCC Time Sync on both physical transports to keep the archive gap-free.

12. FAQ