Overview: PCS 7 Communication Architecture and the Role of BCE
The SIMATIC PCS 7 process control system uses a layered network model with three logical buses: the terminal bus (OS/server/engineering station LAN), the plant bus (automation system LAN), and the field bus (PROFIBUS DP / PROFINET to remote I/O and field devices). Operator stations, engineering stations, and the automation systems (AS) communicate over Industrial Ethernet, but they require specific PC interface cards and licenses to participate in the SIMATIC S7 protocol family (S7 communication, S7 routing, ISO-on-TCP, TCP, and PROFINET IO).
The BCE (Basic Communication Ethernet) is the entry-level PC interface used in PCS 7. It is essentially an "IE General" Ethernet port with a SIMATIC-specific license that turns it into a usable PCS 7 OS/ES interface. Higher-end applications use the CP 1623 and CP 1628 communication processors, which provide hardware-assisted protocol processing and redundancy support.
The question of whether a BCE card can be integrated into an "HP Ordinary PC" (any commercial off-the-shelf PC with an Ethernet port) is the most common point of confusion when commissioning PCS 7 on non-SIMATIC hardware. The short answer: yes, the Ethernet hardware is interchangeable, but the SIMATIC software stack and license must still be installed, and the PC must meet the documented performance and operating-system prerequisites.
BCE (Basic Communication Ethernet) Card Fundamentals
The BCE is a software license and configuration profile, not a dedicated NIC. From a hardware perspective, any standard 100/1000 Mbit/s Ethernet controller recognized by Windows (Intel, Broadcom, Realtek, etc.) can host a BCE. From a software perspective, the BCE profile adds the SIMATIC NET runtime required for S7 communication and OS/AS data exchange on the terminal bus and plant bus.
BCE Capabilities
- Connects a single OS, ES, or OS server to the plant bus.
- Supports up to 8 underlying automation systems (single AS configuration only).
- Provides ISO-on-TCP, TCP, and S7 communication services required by WinCC, PCS 7 OS, and the engineering tool.
- Software protocol stack runs on the host CPU (no dedicated communication processor).
- Does not support redundant AS (S7-400H) connections without a CP 1623/CP 1628.
BCE Limitations
- No hardware-assisted communication, so the host CPU handles all protocol processing.
- No support for PROFINET IO controller/device functions (PROFINET CBA only with Softnet).
- No redundant plant bus interface in the standard BCE profile.
- Single OS license per BCE port; multiple BCE ports require additional licenses.
CP 1623 and CP 1628 Industrial Communication Processors
The CP 1623 (6GK1162-3AA00) and CP 1628 (6GK1162-8AA00) are PCI Express communication processors designed specifically for SIMATIC PCS 7 and SIMATIC NET installations. They are identical in form factor and base function but differ in their supported redundancy scenarios.
CP 1623 — Standard Communication Processor
The CP 1623 is the workhorse PC interface card for PCS 7 OS, ES, and OS server stations. It implements the SIMATIC NET protocol stack on dedicated hardware, offloading communication from the host CPU.
- Order number: 6GK1162-3AA00 (CP 1623, PCIe x1).
- Supports up to 64 AS connections (single station or redundant AS-S7-400H).
- Provides ISO, TCP, and S7 communication services.
- Recommended for OS servers handling many AS connections.
CP 1628 — Hardened Communication Processor
The CP 1628 adds extended diagnostics and is the preferred choice for redundant OS servers and PCS 7 V9.x installations.
- Order number: 6GK1162-8AA00 (CP 1628, PCIe x1).
- Same AS connection count as CP 1623 (up to 64).
- Enhanced diagnostics through SIMATIC NET OPC and station configurator.
- Mandatory in many PCS 7 V9 redundant OS server configurations.
BCE vs CP 1623 vs CP 1628: Capability Comparison
| Feature | BCE | CP 1623 | CP 1628 |
|---|---|---|---|
| Hardware | Standard NIC (Intel/Broadcom/Realtek) | PCIe card 6GK1162-3AA00 | PCIe card 6GK1162-8AA00 |
| Protocol processing | Host CPU | Onboard ASIC | Onboard ASIC + extended diagnostics |
| Max AS connections | 8 (single only) | 64 (single or redundant) | 64 (single or redundant) |
| S7-400H redundant AS | No | Yes | Yes |
| Redundant plant bus | No | Yes (with second CP) | Yes (with second CP) |
| License required | BCE license (per OS/ES) | Included with SIMATIC NET CP 1623 driver CD | Included with SIMATIC NET CP 1628 driver CD |
| PROFINET IO controller | No | No | No |
| Typical use | Small OS/ES on standard PC | OS server, large OS, redundant AS | Redundant OS server, PCS 7 V9 |
Licensing Requirements: BCE, Softnet, and SIMATIC PC
The physical Ethernet port is not the licensing unit in PCS 7 — the SIMATIC NET runtime is. You must purchase and activate a license for the protocol stack regardless of which NIC you install. Three license flavors are commonly encountered:
BCE License
The BCE license is the minimum entry license for an OS/ES to talk to the plant bus. It is sold as a single OS license and includes the SIMATIC NET S7/IE communication runtime. It does not enable PROFINET IO controller functionality.
Softnet-S7 / Softnet-IE
Softnet licenses enable the PC to act as an S7 client or server with full S7 communication services. Softnet is required when the PC needs to act as an OPC server for S7 data, perform S7 routing, or participate as a S7 client outside of the basic PCS 7 OS/ES role.
SIMATIC PC License Bundles
When a SIMATIC industrial PC (IPC) is purchased with PCS 7 pre-installed, the BCE/Softnet license is typically included in the bundle. On standard PCs, the license must be purchased separately and activated through the Automation License Manager (ALM).
Hardware Compatibility: SIMATIC vs Standard PC
Siemens qualifies PCS 7 on specific SIMATIC IPC platforms (IPC227G, IPC547G, IPC647D, IPC847D, etc.). These are validated configurations with guaranteed driver support, Windows version compatibility, and BIOS settings.
A standard commercial PC (e.g., HP EliteDesk, Dell OptiPlex, Lenovo ThinkCentre) can be used when:
- The Ethernet controller is on the SIMATIC NET compatibility list for the target PCS 7 version.
- The Windows version is on the supported list (Windows Server 2016/2019/2022, Windows 10 LTSC for engineering stations).
- The PC has the CPU resources to handle the protocol stack (see CPU section below).
- The BIOS settings enable SR-IOV only when explicitly supported by the OS configuration.
Ethernet Controller Considerations
The BCE profile is essentially "IE General" — it does not require a specific chipset. However, two practical caveats apply:
- Offload engines: Some Intel i219/i225/i226 chipsets use hardware checksum offload. SIMATIC NET S7 communication generally works with checksum offload, but jumbo frames and TCP segmentation offload should be disabled on the plant bus interface to avoid fragmented ISO-on-TCP PDUs.
- Multiple BCE instances: If the OS/ES needs two BCE interfaces (e.g., one on terminal bus, one on plant bus), each NIC must be configured as a separate BCE instance in the SIMATIC NET Configuration Console, and each requires its own BCE license.
CPU and Performance Considerations
Because the BCE runs the SIMATIC NET protocol stack on the host CPU, PC performance is a real constraint. Approximate CPU load guidelines:
| Configuration | Recommended CPU | RAM | Notes |
|---|---|---|---|
| ES single station, ≤2 AS | Intel Core i5 (4 cores) | 16 GB | Minimal load |
| OS single station, 8 AS (BCE limit) | Intel Core i7 (4–6 cores) | 16 GB | Archive + alarm logging on same host |
| OS server with CP 1623 | Xeon E3 / Core i7 | 32 GB | CP offloads, CPU mostly free for WinCC |
| Redundant OS server pair with CP 1628 | Xeon E-2200 / equivalent | 32 GB | OS redundancy + process value archive |
| Engineering station (multi-project) | Xeon W / Core i9 | 32–64 GB | Compiler + CFC/SFC + bulk download |
Configuration in PCS 7 Engineering Software
Step 1 — Install the SIMATIC NET Runtime
On a standard PC, install SIMATIC NET PC software from the installation media matching the PCS 7 version (e.g., SIMATIC NET V16 for PCS 7 V9.0, V17 for V9.1). The install prompts for:
- Communication protocols (S7, PROFINET, OPC UA).
- Station Configuration Editor (SCE) components.
- Automation License Manager integration.
Step 2 — Configure the BCE in the Station Configuration Editor
Open the Station Configuration Editor (Start → SIMATIC → SIMATIC NET → Configuration → Station Configuration Editor) and add a BCE module:
- Right-click Station → Add component → select BCE from the module catalog.
- Assign the BCE instance to the physical Ethernet adapter (use MAC address binding, not the Windows adapter name, to avoid issues after driver updates).
- Set the BCE mode to "IE General" (the only mode supported for OS/ES plant bus communication).
- Compile and download the PC station configuration.
Step 3 — Configure the S7 Connection in NetPro / HW Config
In PCS 7 Engineering (HW Config or NetPro), add the OS/ES station and define the S7 connection to the AS:
- Insert a new S7 connection from the OS/ES PC station to the AS CPU.
- Set the connection type to S7 connection.
- Enter the IP address of the BCE-bound NIC on the plant bus subnet.
- Configure the connection resource (TSAP) on the AS side — typically the default slot 1 TSAP for S7-400.
- Download the connection configuration to both the PC station and the AS.
Step 4 — Activate the License
Open the Automation License Manager and verify the BCE license is recognized. If the license is not detected, the S7 channel in WinCC will report "Internal error" and the OS will not start in runtime.
Verification and Diagnostics
Verification Checklist
- BCE instance in Station Configuration Editor shows "RUN" green status.
- SIMATIC NET diagnostics (Start → SIMATIC → SIMATIC NET → Commissioning → Diagnostics) shows the S7 connection as established.
- WinCC channel diagnosis (WinCC Explorer → Channel Diagnosis → S7) shows "OK" for all configured AS connections.
- Automation License Manager shows the BCE license as valid (not in the "Missing licenses" view).
- Ping test from the PC station to the AS CPU IP address returns < 10 ms on the plant bus subnet.
- OS runtime starts and the process picture displays live values from all configured AS.
Common Diagnostic Output
When the BCE is configured correctly, the S7 channel diagnostic shows:
Connection: AS01_PlantBus
Status: OK
Established since: 2024-05-12 08:14:23
Last error: --
Reconnect attempts: 0
Diagnostic Tools
| Tool | Purpose | Location |
|---|---|---|
| Station Configuration Editor | BCE/CP instance status | SIMATIC NET → Configuration |
| SIMATIC NET Diagnostics | S7 connection status | SIMATIC NET → Commissioning |
| WinCC Channel Diagnosis | Runtime channel state | WinCC Explorer → Tools |
| Automation License Manager | License validation | Start → Siemens Automation |
| Windows Event Viewer | Driver/runtime errors | Application & System logs |
Troubleshooting Matrix
| Symptom | Probable Cause | Action |
|---|---|---|
| OS reports "License not found" | BCE/Softnet license not activated | Reinstall license via Automation License Manager; check license USB dongle or OLM key |
| S7 connection state "Down" in diagnostics | BCE instance not running or wrong NIC bound | Check Station Configuration Editor; rebind to correct MAC address |
| OS freezes periodically under high load | CPU undersized for BCE + archive | Move to CP 1623 or upgrade CPU; check WinCC archive configuration |
| Only some AS connect (works for 6 of 8) | Approaching BCE 8-AS limit or subnet issue | Reduce AS count or upgrade to CP 1623/CP 1628 (64 AS) |
| Redundant AS pair not connecting | BCE does not support S7-400H redundancy | Replace BCE with CP 1623 or CP 1628 |
| Connection drops after Windows update | NIC driver update changed NIC binding | Rebind BCE to MAC address; pin NIC driver version |
| Ping works but S7 fails | Firewall blocking ISO-on-TCP port 102 | Disable Windows Firewall or add TCP/102 inbound rule on plant bus interface |
| Long latency on plant bus | Switch not QoS-aware or duplex mismatch | Set switch port to 100 Mbit/s full duplex; enable QoS for SIMATIC frames |
Plant Bus Design Notes
The plant bus is the Ethernet segment that connects the AS to the OS/ES. PCS 7 uses the plant bus for:
- OS-AS data exchange (process values, alarms, operator commands).
- ES-AS engineering download and online diagnostics.
- S7 routing from the ES through the plant bus to PROFIBUS DP / PROFINET subnet.
- Time synchronization between OS servers and AS.
Best-practice plant bus design when using BCE:
- Use a dedicated VLAN for the plant bus, separate from the terminal bus.
- Deploy managed switches with QoS prioritization for SIMATIC frames (DSCP 46 or 802.1p priority 6).
- Hard-set Ethernet speed and duplex on both the BCE NIC and the switch port.
- Disable energy-efficient Ethernet (EEE / Green Ethernet) on the plant bus NIC.
- Limit multicast/broadcast on the plant bus VLAN to avoid AS CPU overload.
Frequently Asked Questions
Can I use a BCE communication card on an ordinary HP PC with PCS 7?
Yes. The BCE profile is a software license, not a dedicated NIC. Any standard Ethernet controller recognized by Windows can host a BCE, provided the SIMATIC NET runtime and BCE license are installed via the Automation License Manager. The PC must meet the CPU and operating-system prerequisites for the target PCS 7 version.
How many automation systems can a BCE connect to?
A BCE supports up to 8 underlying automation systems in a single-station configuration only. For more than 8 AS, or for redundant S7-400H AS connections, use a CP 1623 (6GK1162-3AA00) or CP 1628 (6GK1162-8AA00), both of which support up to 64 AS connections.
Do I need a Softnet license if I have a BCE license?
It depends on the role. A BCE license is sufficient for an OS/ES station performing standard S7 communication on the plant bus. If the PC must act as an OPC server for S7 data, perform S7 routing, or run a Softnet-based PROFINET application, a Softnet-S7 or Softnet-IE license is required in addition to the BCE.
Can a BCE be used with a redundant S7-400H automation system?
No. The BCE profile does not support redundant AS connections. For S7-400H redundant AS pairs, you must use either a CP 1623 or CP 1628 communication processor in the OS server.
Why does my OS show "Connection failed" even though ping works?
Most often this is the Windows Firewall blocking ISO-on-TCP port 102, which the S7 protocol uses. Add an inbound rule for TCP/102 on the plant bus NIC, or disable the firewall on the plant bus interface. Other causes include a missing BCE license, wrong TSAP, or the BCE instance bound to the wrong NIC in the Station Configuration Editor.