Comparing Basic Communication Ethernet (BCE) and CP 1623 Interfaces on PCS 7 Plant Bus

You can use an ordinary commercial Ethernet card (configured as 'IE General') in a standard PC for SIMATIC PCS 7 plant bus communication using the Basic Communication Ethernet (BCE) framework. However, standard BCE licenses strictly support non-redundant S7 communication to single AS controllers (up to 8 AS stations). For communicating with redundant S7-400H or CPU 410-5H controllers over commercial network cards, you must purchase a 'SOFTNET-IE S7 REDCONNECT' license. Dedicated Siemens CP cards (CP 1623 / CP 1628) with 'HARDNET-IE S7 REDCONNECT' offload protocol processing to an onboard coprocessor, supporting up to 64 fault-tolerant connections.

Executive Summary

When designing PCS 7 Engineering Stations (ES) or Operator Stations (OS), system integrators must decide between using standard commercial network interface cards (NICs) via the Basic Communication Ethernet (BCE) concept or investing in dedicated Siemens Industrial Ethernet communication processors (such as the PCI-Express CP 1623 or CP 1628). Commercial PCs easily accept standard NICs, leading engineers to ask whether expensive CP cards are strictly necessary. This article contrasts the technical capabilities, licensing boundaries, CPU overhead, and architectural limits of BCE versus CP 1623/CP 1628.

Architectural and System Mechanics

Architectural Comparison of BCE and Industrial CP Cards:

Basic Communication Ethernet (BCE / IE General):
Hardware: Standard commercial PCI-Express or onboard Gigabit Ethernet NICs (e.g., Intel I210/I350).
Protocol Processing: Software-based (SOFTNET). Protocol stacks execute entirely on the host PC's CPU, consuming computing cycles during heavy traffic.
Connection Ceiling: Supports up to 8 non-redundant AS single stations.
Redundancy Limitation: Standard BCE does not support fault-tolerant redundant S7 connections. If connecting to S7-400H, the PC requires a SOFTNET-IE S7 REDCONNECT license.
Industrial Communication Processors (CP 1623 / CP 1628):
Hardware: Dedicated Siemens PCI-Express card with an onboard ARM communications processor and integrated 2-port switch.
Protocol Processing: Hardware-based (HARDNET). Offloads 100% of the S7 protocol stack and time-stamping from the host CPU.
Connection Ceiling: Supports up to 64 fault-tolerant redundant S7 connections.
High Availability: Hardware-level failover between redundant plant bus subnets without Windows driver intervention.

Step-by-Step Engineering and Implementation Procedure

Step 1: Evaluate System Architecture and Availability Requirements

Select the appropriate communication interface:
- Scenario A: Small plant, single AS controller (non-redundant CPU 414/416), <= 8 controllers. Use Standard NIC with BCE / SOFTNET-IE S7.
- Scenario B: Redundant controllers (S7-400H / CPU 410-5H) using commercial PC hardware. Use Standard NICs with SOFTNET-IE S7 REDCONNECT.
- Scenario C: Medium to large plant, redundant controllers, high tag volume, > 8 controllers, mission-critical OS Servers. Use Siemens CP 1623 with HARDNET-IE S7 REDCONNECT.

Step 2: Configure IE General in STEP 7 HW Config (For BCE)

Open the SIMATIC PC Station in HW Config.
In the catalog, navigate to SIMATIC PC Station -> CP -> Industrial Ethernet -> IE General.
Insert IE General into the designated PC slot.
Assign the plant bus IP address and subnet mask.

Step 3: Configure Station Configuration Editor

On the PC station, launch the Station Configuration Editor.
Add an IE General component in the identical slot number configured in HW Config.
Bind the component to the physical Windows network adapter connected to the plant bus.

Step 4: Install Required Licenses in Automation License Manager

For single AS: Transfer SIMATIC NET SOFTNET-IE S7 license to drive C:.
For redundant AS: Transfer SOFTNET-IE S7 REDCONNECT license to drive C:.
For CP 1623: Transfer HARDNET-IE S7 REDCONNECT license to drive C:.

Verification

To verify plant bus communication:
1. Open the SIMATIC NET diagnostic tool 'Communication Settings' -> 'Diagnostics'.
2. Verify that active S7 connections report status 'ESTABLISHED'.
3. In Automation License Manager, verify that the communication license shows active check-out without deficit warnings.
4. Start WinCC Graphics Runtime; confirm process values update without communication alarms.

Limitations and Operational Precautions

Operational precautions:
- When deploying BCE on commercial NICs, disable all energy-saving features (Energy Efficient Ethernet, Green Ethernet, sleep modes) in Windows Device Manager.
- Standard commercial network cards do not support hardware time-stamping of alarms with 1ms resolution; high-accuracy sequence of events (SOE) requires CP 1623 or ET 200SP HA time stamping.
- Do not use the same physical network card for both the terminal bus and the plant bus; physical network separation is mandatory in PCS 7.

Engineer FAQ

Q: Can I use an ordinary HP or Dell PC for PCS 7 plant bus communication?

A: Yes, by configuring the network card as 'IE General' in STEP 7 and installing the appropriate SIMATIC NET license.

Q: Is a BCE license sufficient for redundant S7-400H controllers?

A: No. Standard BCE does not support fault-tolerant redundant S7 connections; redundant controllers require a SOFTNET-IE S7 REDCONNECT license.

Q: What is the primary technical advantage of a CP 1623 card?

A: CP 1623 features an onboard microprocessor that offloads 100% of communication protocol handling from the host PC CPU and supports up to 64 redundant connections.

Q: How many connections does standard BCE support?

A: Standard BCE supports up to 8 non-redundant AS connections.

Q: What network speed is required for the plant bus?

A: 100 Mbps or 1 Gbps full-duplex switched industrial Ethernet.

Technical References

Related Tags

BCE, CP 1623, SOFTNET-IE S7, REDCONNECT, Plant Bus

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Comparing Basic Communication Ethernet (BCE) and CP 1623 Interfaces on PCS 7 Plant Bus