CP1623 vs CP1625: Selecting Siemens NICs for PCS 7 Networks

Overview: CP1623 and CP1625 in a PCS 7 Context

Selecting the correct PCI Express network interface card (NIC) is a frequent point of confusion when engineering stations (ES), operator stations (OS), and SIMATIC PCS 7 controllers must coexist on a single plant network. Two part numbers dominate this decision: the 6GK1162-3AA00 CP 1623 and the 6GK1162-5AA00 CP 1625. Both cards occupy a PCIe slot, both carry the Siemens SIMATIC NET firmware stack, and both are intended for industrial PCs, yet they target fundamentally different OSI layers.

CP 1623 is a communications processor for Industrial Ethernet used at the PCS 7 plant bus level. CP 1625 is a communications processor for PROFINET engineered for the S7-1500 software controller and TIA Portal. The two are not interchangeable, and at the time of writing, the CP 1625 is not included in the released module list for PCS 7 V9.1 SP2, which constrains the choice to CP 1623 or CP 1628 for any PCS 7 engineering station that must communicate on the plant bus.

This reference consolidates the published Siemens guidance, the PCI Express slot requirements that govern migration from the legacy CP 1613 A2, and the architectural reasoning behind the PCS 7 plant bus / terminal bus separation so that an automation engineer can specify the correct part number on the first attempt.

Hardware Identity and PCI Express Slot Requirements

Both cards are full-height, half-length PCIe x1 devices intended for industrial PCs and SIMATIC panel PCs. The mechanical envelope, however, hides a meaningful migration constraint relative to older part numbers.

When replacing a CP 1613 A2 with a CP 1623, the host PC must expose a free PCI Express slot; the older PCI or PCI-X mechanical slot used by the CP 1613 A2 is no longer electrically compatible. This requirement is documented in Siemens Knowledge Base article 50710358 - What are the requirements for changing from CP1613 A2 to CP1623? Verify PCIe availability before quoting either CP 1623 or CP 1625 in a retrofit bid.

Protocol Stack Comparison

The functional divergence between the two cards lives in the protocol stack that the firmware presents to the operating system and to the engineering tools.

The CP 1623 binds to the Windows NDIS stack as a standard Industrial Ethernet adapter and exposes ISO-on-TCP plus TCP/IP sockets. It is the conduit for S7 communication between the PCS 7 ES, OS, AS, and the SIMATIC station manager. The CP 1625 instead binds to the PROFINET driver layer; it does not behave like a generic NIC for IT traffic and must be configured from TIA Portal rather than from the Windows network control panel.

PCS 7 Architecture: Plant Bus Versus Terminal Bus

PCS 7 strictly separates the engineering network into two physical or logical layers. Misunderstanding this separation is the root cause of nearly every CP 1623 versus CP 1625 question on Siemens support. The two layers are described in Entry ID 72887082 - PROFINET in PCS 7 Guidelines and Blueprints.

• Plant Bus (Terminal Bus in older PCS 7 manuals): An Industrial Ethernet network that interconnects engineering stations (ES), operator stations (OS), the SIMATIC station manager, the asset management server, and the AS CPUs. It carries S7 communication, time synchronization, OPC, WinCC archive data, and project engineering downloads. The PC-side NICs permitted on this bus are CP 1623 and CP 1628, both with PCIe host bus connectors, and both supporting Industrial Ethernet protocols only.
• Terminal Bus (Field Bus): A PROFINET network that interconnects the AS CPUs with distributed I/O (ET 200SP, ET 200MP), drives (SINAMICS via PROFINET), motor starters (SIMOCODE), and field instrumentation. CPUs connect to the terminal bus through their integrated PROFINET interfaces or through dedicated rack-mounted PROFINET communications processors such as CP 443-1 on the S7-400 / AS 410 side.

The selection matrix below emerges directly from this architecture:

Selection Guide: When to Specify Each Card

Specify CP 1623 when:

1. The PC is a PCS 7 engineering station, operator station, or SIMATIC station manager on the plant bus.
2. The plant bus exchanges S7 communication, OPC UA / OPC DA, archive replication, or NTP time with the AS 410 controllers.
3. The host PC has only free PCI Express slots (no PCI or PCI-X).
4. The plant bus requires standard Windows TCP/IP applications in parallel with PCS 7 traffic.

Specify CP 1625 when:

1. The PC hosts a S7-1500 Software Controller (CPU 1505S / CPU 1507S) that must exchange PROFINET IO data with distributed field devices.
2. The project is engineered in TIA Portal, not PCS 7, and the PC requires deterministic PROFINET RT or IRT communication.
3. The PROFINET interface must be isolated from the Windows NDIS stack for performance or cycle-time reasons.

Why CP 1625 Is Not Supported in PCS 7 V9.1 SP2

The current released module list for PCS 7 V9.1 SP2 enumerates the approved PC-side communications processors. According to Entry ID 109754965 - Released modules for PCS 7 V9.1 SP2, the CP 1625 is not among the supported modules. The PC-side options for the plant bus remain CP 1623 and CP 1628 (PCI Express) plus legacy CP 1613 A2 and CP 1616 where existing hardware is retained.

Practically, this means a project that mixes PCS 7 plant bus traffic with S7-1500 software controllers must:

1. Install two distinct NICs in the same industrial PC: one CP 1623 (or CP 1628) bound to the plant bus, and one CP 1625 bound to the S7-1500 software controller PROFINET line.
2. Configure the CP 1623 from the Windows network control panel and the SIMATIC NET configuration tools used by PCS 7.
3. Configure the CP 1625 from TIA Portal, project the S7-1500 software controller, and bind its PROFINET interface to the CP 1625 only.
4. Keep the two networks physically or logically separated (different VLAN or different switch infrastructure) to prevent PROFINET RT frames from contending with plant bus S7 traffic.

This dual-NIC topology is the only sanctioned way to combine PCS 7 plant bus communication with PROFINET IO controller functionality on a single PC as of the V9.1 SP2 release.

Installation and Configuration Sequence

1. Verify the PCIe slot. Power down the industrial PC, open the chassis, and confirm an empty PCIe x1 (or larger) slot is free. PCI and PCI-X slots will not accept a CP 1623.
2. Seat the card. Insert the CP 1623 or CP 1625 into the slot, secure the bracket, and reconnect power.
3. Install SIMATIC NET or TIA Portal driver package. For CP 1623 in a PCS 7 station, install the PCS 7-approved SIMATIC NET version. For CP 1625 in a TIA Portal station, install the TIA Portal component "PROFINET driver for CP 1625" matching the TIA Portal major version.
4. Configure the connection in the engineering tool. In PCS 7 (component view), bind the plant bus interface to the CP 1623 MAC address. In TIA Portal (device view), assign the CP 1625 as the PROFINET interface of the S7-1500 software controller.
5. Configure IP parameters. Set a static IPv4 address from the PCS 7 plant bus subnet for the CP 1623. Leave PROFINET device names and IP addresses assigned via DCP for the CP 1625 PROFINET segment.
6. Verify link and diagnostics. Use the SIMATIC station manager and the CP 1623 web-based diagnostics page to confirm link state. Use TIA Portal "Online & Diagnostics" on the CP 1625 to confirm PROFINET IO device reachability.

Migration Path from Legacy Cards

The CP 1613 A2 (PCI / PCI-X) and CP 1616 (PCI / PCI-X) predecessors are still found in long-lived PCS 7 V8.x stations. When those stations are refreshed to PCS 7 V9.x or when the host PC is replaced, the PCIe constraint becomes binding:

If the replacement PC has no PCIe slot, the migration cannot proceed with the CP 162x family and an industrial PC with PCIe must be sourced. Reference Knowledge Base article 50710358 for the formal PCIe requirement.

Verification Checklist After Commissioning

1. From the ES, ping the CP 1623 IP address of the OS and confirm S7 connection establishment to each AS 410.
2. From WinCC Explorer on the OS, verify that all S7 connections report status "connected" and that the redundancy partner (if applicable) is reachable.
3. From the TIA Portal project hosting the S7-1500 software controller, go online and confirm that the CP 1625 reports the assigned PROFINET device name.
4. From TIA Portal, compile and download the PROFINET topology; verify that every configured IO device reaches "connected" state without diagnostic interrupts.
5. Capture a Wireshark trace on the plant bus (with a span port) and confirm S7 frames carry ISO-on-TCP (port 102) traffic; capture a PROFINET trace on the terminal bus and confirm RT frames at the configured send clock (typically 1 ms).
6. Validate that no PROFINET frames appear on the CP 1623 port and no S7 frames appear on the CP 1625 port - the two networks must remain isolated.

Troubleshooting Matrix

Summary and Field-Proven Caveats

• CP 1623 is the sanctioned PC-side NIC for the PCS 7 plant bus; CP 1625 is the sanctioned NIC for the S7-1500 software controller on PROFINET.
• Both cards require a PCI Express slot - PCI and PCI-X legacy slots are incompatible, even though the older CP 1613 A2 physically fits.
• CP 1625 is not in the released module list for PCS 7 V9.1 SP2; do not specify it as the sole plant bus NIC in a PCS 7 station.
• A single industrial PC can host both cards simultaneously to combine PCS 7 plant bus communication with an S7-1500 software controller PROFINET line, provided the two networks are physically or logically separated.
• Always confirm the engineering tool version (PCS 7 component view or TIA Portal device view) supports the specific CP firmware and host driver level before commissioning.

Frequently Asked Questions