Overview: Profibus Communication Processors for Industrial PCs
When a SIMATIC WinCC Runtime station, an engineering workstation, or a third-party SCADA host must communicate with SIMATIC S7 controllers or distributed I/O over PROFIBUS, the host computer requires a dedicated communication processor (CP) module plus the matching SIMATIC NET PC software. The CPs are split into two architectural families: HARDNET modules that carry an onboard protocol controller and SOFTNET modules that offload the PROFIBUS stack to the host CPU. The choice between CP 5622 (SOFTNET) and CP 5623 (HARDNET) is the most common selection decision for new WinCC V7/V8 and WinCC Professional installations today, and it is determined by the number of PROFIBUS connections, master/slave role, bus load, and the form factor available on the host PC.
For a Windows 10 host running WinCC Runtime Professional with PROFIBUS connectivity, both CP 5622 and CP 5623 are released by Siemens. CP 5622 covers the typical WinCC use case (up to 8 PROFIBUS/MPI connections per WinCC station), while CP 5623 is required only when the application exceeds that envelope or needs class-2 master services, FDL, or routing/PG functions with high determinism.
Architectural Difference: HARDNET vs SOFTNET
The HARDNET/SOFTNET split is the single most important technical distinction in the Siemens PC module family and is documented in the SIMATIC NET PC software manual and the Siemens Industry Online Support FAQ 109815705 ("Which PC modules / CPs are approved for which SIMATIC NET software?").
SOFTNET Processors (CP 5612, CP 5622, CP 5711)
- Use the host PC's CPU and memory to run the PROFIBUS protocol stack.
- Lower hardware cost; no firmware image on the module itself beyond the physical layer and a small bus interface.
- Supported roles: DP master class 1, DP slave, MPI, S7 communication (depends on the licensed SIMATIC NET variant installed).
- Maximum number of DP slaves and S7 connections is limited by the licensed SOFTNET edition (e.g., SOFTNET-DP, SOFTNET-S7).
- Latency is influenced by Windows scheduling; not recommended for very tight deterministic loops.
HARDNET Processors (CP 5613 A3, CP 5623)
- Contain an onboard ASIC/microcontroller that runs the PROFIBUS protocol stack independently of the host CPU.
- Support DP master class 1 and class 2, FDL, S7 communication, PG/OP routing, and open IE/PB link functionality (depending on licensed variant).
- Deliver deterministic bus access even when the host CPU is fully loaded by WinCC, the HMI, or a database.
- Higher per-unit cost and longer lead time; firmware updates shipped as SIMATIC NET upgrades.
| Attribute | SOFTNET (CP 5622) | HARDNET (CP 5623) |
|---|---|---|
| Bus protocol engine | Host CPU (Windows process) | Onboard ASIC/microcontroller |
| DP master class 1 | Yes (license permitting) | Yes |
| DP master class 2 | No | Yes |
| DP slave | Yes | Yes |
| S7 communication / FDL | Yes | Yes |
| Determinism under host CPU load | Reduced | High |
| Typical WinCC connection count | Up to 8 PROFIBUS/MPI | Up to 8 PROFIBUS/MPI |
| Form factor | PCIe x1 | PCIe x1 |
| Recommended for WinCC RT | Yes (typical) | Yes (high-load/multi-PLC) |
SIMATIC NET PC Module Family for Windows 10 Hosts
Siemens has shipped four PROFIBUS CP families for industrial PCs. Only the active, on-sale variants should be specified for new projects; legacy PCI cards are still supported but are typically not available for new procurement.
| Article number | Module | Bus | Form factor | Family | Status for new projects |
|---|---|---|---|---|---|
| 6GK1561-2AA00 | CP 5612 | PROFIBUS / MPI | PCI (5 V) | SOFTNET | Phased out, still in stock at distributors |
| 6GK1561-3AA01 | CP 5613 A3 | PROFIBUS / MPI | PCI (5 V) | HARDNET | Phased out, still in stock at distributors |
| 6GK1562-2AA00 | CP 5622 | PROFIBUS / MPI | PCIe x1 | SOFTNET | Current; recommended for new WinCC RT |
| 6GK1562-3AA00 | CP 5623 | PROFIBUS / MPI | PCIe x1 | HARDNET | Current; recommended for high-load |
| 6GK1571-1AA00 | CP 5711 | PROFIBUS / MPI | USB 2.0 | SOFTNET | Current; commissioning and small stations |
Selecting Between CP 5622 and CP 5623: Decision Tree
- Confirm the host form factor. If only a PCIe x1 slot is open, both CP 5622 and CP 5623 fit. If only USB is practical (no internal slot, panel-mount PC), specify CP 5711.
- Count required PROFIBUS/MPI connections from WinCC. WinCC V7/V8 and WinCC Professional cap a single station at 8 PROFIBUS/MPI connections. If the count is ≤ 8, the SOFTNET CP 5622 is sufficient.
- Identify the role required on the PC. If WinCC is strictly a client/HMI (no PG routing, no class-2 master), use CP 5622. If the PC must also serve as a programming device (PG), as a PROFIBUS class-2 master, or as an IE/PB link gateway, move to CP 5623.
- Check host CPU headroom. WinCC RT archives, alarm logging, OPC, and visualization on the same CPU as the SOFTNET stack can starve the stack under load. If the WinCC archive database is large or trending is heavy, prefer HARDNET.
- Validate against SIMATIC NET version. Both CPs are supported by current SIMATIC NET PC software. The licensed "S7-PM-S" / "S7-DP-S" / "S7-FDL" / "S7-Routing" components must be present.
WinCC Runtime Professional Compatibility
WinCC V7/V8 and WinCC Professional (TIA Portal) ship with the SIMATIC NET channel unit and require a PC CP only if PROFIBUS is the selected network. The relevant facts engineers need:
- Approved modules for WinCC V7/V8: CP 5612, CP 5622 (SOFTNET) and CP 5613 A3, CP 5623 (HARDNET), plus CP 5711 for engineering or small single-PLC stations.
- Connection limit per WinCC station: 8 PROFIBUS/MPI connections (WinCC V7/V8 and WinCC Professional). Beyond that, an additional CP must be installed (each module provides its own connection count).
- Driver: "SIMATIC S7 Protocol Suite" channel, with the "PROFIBUS" unit selecting the CP via the S7ONLINE access point.
- Operating system: Windows 10 (64-bit) is supported by current SIMATIC NET versions and by current WinCC Professional releases; verify the exact SIMATIC NET edition against the WinCC compatibility list before commissioning.
Part Number Reference and Bundled Licenses
When ordering, remember that the CP module is hardware only. The corresponding SIMATIC NET software license must be ordered separately and installed on the host:
| Function | SIMATIC NET license article no. (typical) | Notes |
|---|---|---|
| SOFTNET-DP slave (single CP) | 6GK1704-1LW70-3AA0 | Enables DP slave on CP 5622 |
| SOFTNET-S7 (single CP, 1 connection) | 6GK1704-1LW71-3AA0 | WinCC PROFIBUS HMI connection |
| SOFTNET-S7 (single CP, up to 4 connections) | 6GK1704-1LW72-3AA0 | Mid-size WinCC |
| HARDNET-FDL | 6GK1716-1CB70-3AA0 | Free-layer FDL on CP 5623 |
| HARDNET-DP master | 6GK1716-1CB71-3AA0 | DP master class 1 + 2 on CP 5623 |
| HARDNET-IE/PB Link | 6GK1716-1CB74-3AA0 | Gateway IE ↔ PB on CP 5623 |
License numbers above match the conventional SIMATIC NET V18/V19 generation; always cross-check the current catalog and the WinCC compatibility list in the Siemens Industry Online Support portal before placing a PO.
Installation Procedure on a Windows 10 IPC
- Power down the IPC, open the chassis, and seat the CP into a free PCIe x1 slot (CP 5622 / CP 5623) or plug the CP 5711 into a USB 2.0/3.0 port.
- Connect the 9-pin D-sub PROFIBUS connector to the trunk or drop cable. The CP 5622/CP 5623 ships with a PROFIBUS D-sub connector that includes a 4-pin DIP switch for terminating resistance (ON at both ends of a segment, OFF everywhere else).
- Power on the host and install the matching SIMATIC NET PC software edition. The Configuration Console will then enumerate the new CP under "Modules".
- Open SIMATIC NET Configuration Console, set the CP's Station Address (PROFIBUS node number, 1–126, must be unique on the segment), and set the S7ONLINE access point to the correct CP.
- In TIA Portal or STEP 7, add the WinCC station's CP to the PROFIBUS network view, set the bus parameters (187.5 kbps to 12 Mbps), and configure the WinCC S7 connections.
- Restart the WinCC Runtime service and verify the connections from the WinCC channel diagnosis ("Status of Connections").
Verification and Commissioning Checks
After installation, perform the following deterministic checks before handing the station over to operations:
- Module visibility: In SIMATIC NET Configuration Console, the CP appears in the module list with the correct article number and firmware version. If it shows yellow, the driver is missing or the slot is wrong.
- Bus status: LED on the CP D-sub housing must show steady green for "active, no error". A flashing red LED indicates bus fault or duplicate station address.
- Live list: In Configuration Console, the "PROFIBUS Live List" lists all reachable nodes including the CPU and any other DP slaves on the segment.
- WinCC connection status: All configured S7 connections must show "Connected" in WinCC channel diagnosis; the per-connection time stamp must update with each scan cycle.
- PG/OP routing test (if applicable): From STEP 7, run "Accessible Nodes" over the CP and confirm that the target S7 CPU is reachable through the WinCC station's CP 5623.
Troubleshooting Matrix
| Symptom | Likely root cause | Resolution |
|---|---|---|
| CP 5622/5623 not listed in Configuration Console | Driver not installed, wrong slot, or BIOS does not enumerate the PCIe card | Reinstall SIMATIC NET, reseat the card, enable the slot in BIOS |
| Live list returns only the local station | PROFIBUS cable reversed, terminator not ON at segment ends, or wrong baud rate | Check D-sub pinout, set terminating resistors ON at both ends, set master and slave baud rate to the same value |
| WinCC reports "Cannot find S7ONLINE access point" | S7ONLINE assignment missing or pointing at a different CP | Open Configuration Console and assign S7ONLINE to the active CP |
| CP LED steady red, WinCC connection times out | Duplicate PROFIBUS address on the segment | Run Live List, identify the duplicate address, reassign one node |
| Connection establishes but data is stale / cyclic break | CPU over-load on the host (SOFTNET) or bus errors | Move to CP 5623, lower WinCC archive rate, check PROFIBUS cable shielding and grounding |
| More than 8 connections required | WinCC station limit reached | Install a second CP, or split the application across multiple WinCC stations |
Field Notes and Best Practices
- Order the SIMATIC NET license at the same time as the CP. The CP will install and enumerate on Windows 10, but WinCC channels will fail to open until the matching SOFTNET/HARDNET license is installed. Procurement delays on the license frequently delay commissioning.
- Match firmware to SIMATIC NET version. CP 5622 and CP 5623 ship with field-loadable firmware that is updated by the SIMATIC NET installer. Mixing a newer CP firmware with an older SIMATIC NET version can cause "module firmware mismatch" warnings.
- Use the PCIe variant for new IPCs. The CP 5622/CP 5623 are the PCIe successors to the legacy CP 5612/CP 5613 A3 (PCI) and share the same SIMATIC NET drivers, making drop-in migration easier.
- Avoid CP 5711 for production WinCC RT. The USB CP 5711 is excellent for commissioning, diagnostics, and engineering laptops but is not the preferred runtime card for a 24/7 production station because USB stack priorities are not deterministic on Windows.
- Document bus parameters. Record the baud rate, segment length, repeater count, and terminating-resistor positions on the cabinet drawing. Most field failures on PROFIBUS are cabling or termination issues, not module failures.
Related Standards and Further Reading
- PROFIBUS overview, PI (PROFIBUS & PROFINET International): www.profibus.com/technologies/profibus
- Siemens Industry Online Support FAQ 109815705 – "Which PC modules / CPs are approved for which SIMATIC NET software?": support.industry.siemens.com → 109815705
- Communications services of the PROFIBUS CMs (S7-1200 CM 1243-5 reference architecture): TIA Portal documentation → PROFIBUS CMs
- Siemens SIMATIC NET product portal: www.siemens.com → PROFIBUS
What is the practical difference between CP 5622 and CP 5623?
CP 5622 is a SOFTNET module (PCIe) that runs the PROFIBUS protocol stack on the host CPU. CP 5623 is a HARDNET module (PCIe) that runs the stack on an onboard controller. For WinCC Runtime Professional with up to 8 PROFIBUS/MPI connections, CP 5622 is sufficient; CP 5623 is required for DP master class 2, FDL, PG/OP routing, IE/PB link gateway functions, or high CPU load on the host.
Can CP 5622 act as a PROFIBUS master?
Yes, but only as a DP master class 1 with a SOFTNET-DP license. Class-2 master services and FDL are HARDNET-only and require CP 5623 with the corresponding HARDNET license.
How many PROFIBUS connections does WinCC V7/V8 or WinCC Professional support?
Each WinCC station supports up to 8 PROFIBUS/MPI connections. If the project requires more, install a second CP and split connections across the two modules; each CP provides its own connection count.
Is the CP 5711 USB adapter suitable for WinCC RT production?
CP 5711 is a SOFTNET-DP USB adapter intended for engineering laptops, diagnostics, and small single-PLC stations. For 24/7 production WinCC Runtime, specify a PCIe CP (CP 5622 or CP 5623) for deterministic, slot-based I/O.
Which SIMATIC NET version is required for CP 5622 / CP 5623 on Windows 10?
Use the SIMATIC NET PC software edition that matches the installed WinCC version (V7/V8 or WinCC Professional) and the host OS. The Configuration Console must recognize the CP and the S7ONLINE access point must point to it before the WinCC channel can establish S7 connections.