C135 PCS 7 (PCS7)
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Licensing and Network Requirements for Redundant AS Communication from Standard PCs in PCS 7

Licensing and Network Requirements for Redundant AS Communication from Standard PCs in PCS 7

To establish plant bus communication between standard, non-Siemens commercial PCs (such as generic Engineering Stations or OS Servers) and a redundant AS controller pair (e.g., dual CPU 410-5H or S7-400H with CP 443-1) without Siemens CP 1623 communication processors, you must install the 'SOFTNET-IE S7 REDCONNECT' license on each PC station. Standard BCE (Basic Communication Ethernet), SOFTNET-IE S7 Lean, or standard SOFTNET-IE S7 licenses do not support fault-tolerant 4-way redundant S7 connections. Each PC communicating redundantly over commercial network interface cards requires its own dedicated REDCONNECT license.

Table of Contents

Executive Summary

In SIMATIC PCS 7 process plants, high-availability controllers (S7-400H / CPU 410-5H) use redundant communication paths to guarantee that no single network or CPU failure interrupts supervisory control. When deploying PCS 7 OS Servers or Engineering Stations on commercial server hardware equipped with standard network cards (NICs) rather than Siemens specialized CP 1623 / CP 1628 industrial Ethernet processors, engineers frequently wonder if basic communication licenses suffice. This article clarifies the licensing boundaries of SIMATIC NET, explains why standard BCE and SOFTNET-IE S7 cannot establish fault-tolerant S7 connections, details the SOFTNET-IE S7 REDCONNECT package, and outlines network configuration requirements.

Architectural and System Mechanics

Redundant S7 communication architecture operates under specific protocol and licensing rules:

  • Fault-Tolerant S7 Connection (4-way Redundancy): In a redundant AS configuration, a single logical S7 connection consists of four underlying physical sub-connections (Subnet A/B from PC to Subnet A/B on CPU/CPs). If any single cable, switch, or controller rack fails, the connection switches transparently in milliseconds.
  • HARDNET vs SOFTNET Communication:
  • HARDNET-IE S7 REDCONNECT: Requires dedicated Siemens communication hardware (CP 1623 / CP 1628) with onboard protocol processors. Offloads network processing from the PC CPU.
  • SOFTNET-IE S7 REDCONNECT: Executes protocol stacks in software on the PC host CPU using standard commercial network interface cards (BCE concept).
  • Licensing Non-Compliance of Basic Packages:
  • SOFTNET-IE S7 Lean: Limited to 8 non-redundant S7 connections. Completely rejects redundant S7 connections.
  • Standard SOFTNET-IE S7: Supports up to 64 non-redundant S7 connections, but cannot arbitrate 4-way fault-tolerant connection pairs.
  • BCE (Basic Communication Ethernet): Legacy driver framework for single S7 connections; cannot sustain redundant S7 failover.

Step-by-Step Engineering and Implementation Procedure

Step 1: Audit Communication Architecture in NetPro

  1. Open NetPro on the Engineering Station.
  2. Select the SIMATIC PC Station (OS Server or ES).
  3. Inspect the connection table: redundant connections to AS 410-5H / S7-400H are defined as 'S7 connection fault-tolerant'.
  4. Confirm that the interface type assigned in the PC Station HW Config is 'IE General' (representing standard commercial NICs).

Step 2: Procure SOFTNET-IE S7 REDCONNECT Licenses

Procure one SOFTNET-IE S7 REDCONNECT license for each physical PC station communicating over fault-tolerant S7 connections:
- For example, SOFTNET-IE S7 REDCONNECT V16 (MLFB: 6GK1704-0HB16-0AA0) or the applicable version matching your installed SIMATIC NET release (V16, V17, etc.).

[!NOTE]
Validate exact MLFB and SIMATIC NET version compatibility with your Siemens catalog or distributor quotation prior to purchasing.

Step 3: Install Licenses via Automation License Manager

  1. Open Automation License Manager (ALM) on each target PC station.
  2. Transfer the SOFTNET-IE S7 REDCONNECT license key from the License USB stick to drive C:.
  3. Check license status to ensure no trial or expiration limitations exist.

Step 4: Configure Station Configuration Editor

  1. On the PC station, open the Station Configuration Editor.
  2. Ensure the two physical network adapters assigned to the plant bus are configured as 'IE General' in matching rack slots as defined in STEP 7 HW Config.
  3. In Simatic Shell, select the terminal bus network adapter.
  4. Download the PC station configuration from NetPro.

Verification

To verify redundant communication:
1. Open SIMATIC NET diagnostic tool 'Communication Settings' -> 'Diagnostics' -> 'Connections'.
2. Verify that the fault-tolerant S7 connection reports status 'ESTABLISHED' with all active subpaths operational.
3. In ALM, verify that the SOFTNET-IE S7 REDCONNECT license is actively checked out by the SIMATIC NET runtime process.
4. Disconnect one plant bus network cable; verify that process data in WinCC runtime continues updating without alarm delays.

Limitations and Operational Precautions

Operational precautions:
- SOFTNET-IE S7 REDCONNECT utilizes host CPU processing power. On heavily loaded systems with hundreds of thousands of process variables, Siemens recommends HARDNET (CP 1623) to eliminate CPU communication overhead.
- Standard NICs must have energy-saving modes ('Green Ethernet', 'Energy Efficient Ethernet') disabled in Windows Device Manager to prevent intermittent connection drops.
- Both physical NICs connected to redundant subnets must operate at identical link speeds (100 Mbps or 1 Gbps).

Engineer FAQ

Q: Can I use SOFTNET-IE S7 Lean for redundant controllers?

A: No. SOFTNET-IE S7 Lean strictly supports non-redundant single S7 connections up to 8 connections only.

Q: Is a REDCONNECT license required for OS Clients?

A: No. OS Clients communicate with the OS Server over the terminal bus and do not communicate directly with the AS controller over the plant bus.

Q: What is the difference between HARDNET and SOFTNET REDCONNECT?

A: HARDNET requires Siemens CP 1623/1628 PCI-Express cards with onboard coprocessors. SOFTNET uses standard commercial Ethernet cards with protocol processing performed by the PC CPU.

Q: How many fault-tolerant connections does SOFTNET-IE S7 REDCONNECT support?

A: SOFTNET-IE S7 REDCONNECT supports up to 16 fault-tolerant S7 connections depending on the SIMATIC NET version.

Q: What happens if REDCONNECT license is missing in ALM?

A: SIMATIC NET displays periodic license deficit warning popups, and the system operates in non-licensed trial mode with potential logging restrictions.

Technical References

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Related Tags

REDCONNECT, SOFTNET-IE S7, Redundant AS, SIMATIC NET, Plant Bus Licensing

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