Fixing SIMOTION I-Device and Device Proxy PROFINET Name Collision

Problem Overview

A SIMOTION D425 motion controller configured in SIMOTION SCOUT V5.3.1.4 acts as a PROFINET I-Device toward an S7-1516F-3 PN/DP safety PLC in a TIA Portal V15.1 Update 3 project. The same SIMOTION controller must also be visible to a TP1200 Comfort HMI panel for diagnostics, operator control, and slot-browsing. Because the TIA Portal project is maintained separately from SCOUT (the SCOUT TIA integration is intentionally not used), the engineer must add the SIMOTION D425 twice to the TIA Portal device and network view: once as an I-Device, generated from the SIMOTION GSD file (GSDML-V*-SIXMO*-*), and once as a Device Proxy, so that the HMI can browse the SIMOTION slot structure without further configuration. Each instance references the same physical controller.

During project compilation, TIA Portal raises the following error against both the I-Device and the Device Proxy entries:

GSD device_1, D425MA-C-A41.PNxIO, D425MA-C-A41.PNxIO:
The PROFINET device name d425ma-c-a41.pnxio is not unique.

The error identifies the duplicate PROFINET station name that is implicitly inherited by both the imported GSD I-Device and the internally created Device Proxy. Removing either one of the two device entries allows the compile to complete successfully, confirming that the duplicate name, not the network topology, is the root cause. The project cannot be loaded to any controller until the collision is resolved.

Root Cause Analysis

PROFINET devices require a unique station name on every PROFINET subnet. The station name is the L2 identifier used during the Discovery and Configuration Protocol (DCP) exchange and is loaded into the device during PROFINET commissioning. TIA Portal enforces uniqueness at compile time because duplicate names cause unrecoverable address-assignment conflicts when the controller is brought online.

In the configuration described in the source case, two TIA Portal device objects both represent the same physical SIMOTION D425:

1. I-Device GSD import. The I-Device functionality is exposed through a GSD file generated by SCOUT. When this GSD is installed, the imported device defaults its PROFINET device name to the value supplied in the GSD, which is typically derived from the SCOUT device name, for example d425ma-c-a41.pnxio.
2. Device Proxy. The Device Proxy is a TIA Portal-only construct that mirrors the I-Device slot structure so that the HMI and other clients can browse the SIMOTION I/O without needing their own GSD import. The Proxy also defaults to the same PROFINET device name because it represents the same physical node.

When TIA Portal compiles the project, the PROFINET IO linker checks the list of all PROFINET stations in the project for duplicate device names. Both objects reference the same physical device and inherit the same default name, so the linker raises the uniqueness violation. Compilation cannot continue until one of the two objects is renamed, placed on a separate subnet, or replaced with a Shared I-Device configuration.

Why does the default name contain a dot?

The default PROFINET device name generated by SCOUT for the SIMOTION D425 takes the form <device-name>.PNxIO. The trailing .PNxIO is a SCOUT convention that distinguishes the PROFINET interface from the station name. While PROFINET station names technically allow the dot character as a separator per the PROFINET specification (IEC 61784-2), in TIA Portal V15.1 this character has caused DCP routing issues in some firmware revisions, and Siemens industry support recommends avoiding dots and any other non-alphanumeric characters other than the dash and underscore.

Why does removing one of the devices not fix the underlying need?

The I-Device is required for the cyclic data exchange between the SIMOTION D425 and the S7-1516F-3. The Device Proxy is required so that the TP1200 Comfort can browse the SIMOTION slot structure and exchange diagnostic or acyclic data. Neither can be omitted without losing a required communication path. The correct resolution preserves both objects while ensuring that they no longer compete for the same station name on the same subnet.

PROFINET Naming Rules and Architecture Constraints

Per the PROFINET specification (IEC 61784-2) and Siemens documentation:

Although dots are technically permitted, Siemens support and field experience indicate that they cause DCP issues with SIMOTION D4x5 firmware V5.x and with many third-party PROFINET tools. The Linux-based firmware on SIMOTION D4x5 (and other newer controllers) treats the dot as an internal namespace separator, which can produce unexpected truncation when the IO Controller issues a DCP identify. Some PROFINET tools also parse station names with strict RFC 1123 hostname conventions and reject dots. The PROFINET device name is independent of the IP host name, so using dots creates confusion in DNS-aware tooling.

Solution Approaches

Four documented approaches resolve the collision. Each has different implications for topology, safety, and commissioning effort.

Siemens industry support ultimately advised the engineer in the source case to use approach 1 (separate subnets). For new projects, approaches 1, 2, or 3 are preferred over approach 4 because they address the underlying architectural cause rather than the symptom.

Solution 1 — Separate PROFINET Subnets for PLC and HMI

The cleanest solution is to give the SIMOTION D425 two PROFINET interfaces and assign each IO Controller (the S7-1516F-3 and the TP1200 Comfort) to its own subnet. Because each PROFINET subnet enforces name uniqueness independently, the same station name can legitimately appear on two different subnets. This avoids any collision check inside TIA Portal and reflects the physical topology.

Topology diagram

S7-1516F-3 PN/DP              TP1200 Comfort
(IO Controller 1)             (IO Controller 2)
      |                              |
      | X1                           | PN/IE
      |                              |
+-----+------------------------------+-----+
|  Subnet A: 192.168.0.0/24 | Subnet B: 192.168.1.0/24  |
|  PROFINET name: d425-if1 | PROFINET name: d425-if2    |
+-----+------------------------------+-----+
      | PNxIO (X1)                  | PNxIO (X2)
      |                            |
+-----+----------------------------+
|  SIMOTION D425                  |
|  X1: 192.168.0.10               |
|  X2: 192.168.1.10               |
+---------------------------------+

Required hardware on SIMOTION D425

The SIMOTION D425 has two PROFINET interfaces onboard (X1 and X2). X1 is the system interface, X2 is the free PROFINET interface. Both can be configured as PROFINET IO Device interfaces. For older D425 variants or firmware V4.x, confirm with SCOUT that both interfaces are available. If only one is shown, install or enable the second interface in the device configuration, or add a CBE30 communication board for an additional port.

Step-by-step configuration

1. In SCOUT: Open the SIMOTION D425 project. Navigate to Properties > PROFINET IO > PN-IO Interface. Confirm that two interfaces (PNxIO and PNxIO-2) are available and enabled.
2. In SCOUT: Export the GSD file for the I-Device: Options > Export GSD. Save the GSDML file and the associated bitmap to a known folder.
3. In TIA Portal V15.1: Options > Manage general station description files (GSD) > install the exported GSDML. Wait until the device appears in the hardware catalog under Other field devices > PROFINET IO > Drives > SIMOTION.
4. In TIA Portal: Drag the SIMOTION I-Device from the catalog onto Subnet A. Connect it to the S7-1516F-3 PN/DP port X1.
5. In TIA Portal: Open the I-Device's PROFINET interface properties. Set the IP address to 192.168.0.10 and the PROFINET device name to d425-if1. Confirm.
6. In TIA Portal: Right-click the SIMOTION I-Device > Create Device Proxy. TIA Portal creates a Proxy device automatically.
7. In TIA Portal: Drag the new Device Proxy onto Subnet B. Connect it to the TP1200 Comfort's PROFINET port. Do not delete the Proxy from the network view; the Device Proxy must exist as a separate object so TIA Portal can route slot-browse data to the HMI.
8. In TIA Portal: Open the Proxy's PROFINET interface properties. Set the IP address to 192.168.1.10 and the PROFINET device name to d425-if2. This is a different name on a different subnet, so the uniqueness check passes.
9. In TIA Portal: Compile the project (both HW Config and the HMI target). Both compilations should complete without the duplicate-name error.
10. In SCOUT: Open Online > Accessible Nodes. Confirm that both interfaces of the D425 respond. Assign the same IP addresses and PROFINET names in SCOUT so that the runtime matches the TIA Portal configuration.

Solution 2 — Shared I-Device Configuration

An I-Device can be shared between two higher-level IO Controllers. This is documented in the TIA Portal help system and on the Siemens documentation portal as "Shared I-Device". With this approach, a single physical PROFINET line carries both controllers, but only one is the IO Controller for a given submodule at any time.

How Shared I-Device works

The I-Device (here the SIMOTION D425) presents its submodules to one or more IO Controllers. Each IO Controller sees only the submodules assigned to it. The I-Device itself is the IO Device toward both IO Controllers, which means:

• The I-Device has one PROFINET station name on one subnet.
• Each IO Controller builds its own Application Relationship (AR) with the I-Device.
• Submodules can be assigned to one IO Controller, multiple IO Controllers, or none.

Shared I-Device is supported by S7-1500 CPUs from firmware V2.6 onward, and by S7-1500 F-CPUs from the same firmware level. Earlier firmware accepts the I-Device but does not negotiate a second AR with the same I-Device, which causes the configuration to compile but fail at runtime.

Step-by-step configuration

1. In SCOUT: Configure a single PROFINET interface on the D425 for shared use. Export the GSD.
2. In TIA Portal: Install the GSD and drag the SIMOTION I-Device onto the shared PROFINET subnet. Connect both the S7-1516F-3 PN/DP port and the TP1200 Comfort PROFINET port to the same physical line, typically via a managed PROFINET switch that supports LLDP forwarding.
3. In TIA Portal: Open the I-Device properties > Operating mode tab. Set Shared I-Device to Enabled.
4. In TIA Portal: For each submodule slot in the I-Device, assign ownership. Submodules for cyclic drive data go to the S7-1516F-3; diagnostic submodules can be assigned to the TP1200 Comfort or to both.
5. In TIA Portal: Compile and load. Both controllers build ARs to the same I-Device.

This approach avoids name collision entirely because only one device object exists for the SIMOTION in TIA Portal. The HMI and the PLC both connect to the same physical station through the same GSD import. The complexity moves from naming to submodule ownership rules.

For more detail on the Shared I-Device topology combined with PROFIsafe, see Shared I-Device and PROFIsafe on the Siemens TIA documentation cloud.

Solution 3 — F-Proxy for PROFIsafe Communication

If the communication involves PROFIsafe telegrams between the S7-1516F-3 and a safety-related slot on the SIMOTION (for example a SINAMICS safety-integrated drive), the F-Proxy acts as the interface between the F-CPU and the drive. The F-Proxy allows transparent routing of PROFIsafe telegrams from the F-CPU via the SIMOTION I-Device to the SINAMICS drive.

Reference configuration documents

• SIMOTION & SINAMICS I-device F-proxy in the TIA Portal — Configuration Manual (PDF, Siemens Support, Attachment ID 50207350).
• Shared I-Device and PROFIsafe — TIA Portal V20 documentation cloud.
• Configuration example for I-device F-Proxy — TIA Portal V20 documentation cloud.

F-Proxy and the I-Device name collision

The F-Proxy is itself a TIA Portal construct that exists in addition to the I-Device GSD. Adding an F-Proxy to the SIMOTION D425 can trigger the same name collision if the F-Proxy defaults to the same PROFINET station name as the I-Device. The resolution is identical: the F-Proxy should be placed on a separate subnet, or the I-Device should be configured as a Shared I-Device with the F-Proxy sitting on a second AR.

Step-by-step configuration of the F-Proxy

1. In TIA Portal: After installing the SIMOTION GSD and adding the I-Device, right-click on the SINAMICS drive beneath the SIMOTION in the device tree.
2. Select "Create F-Proxy". TIA Portal creates the F-Proxy device object that represents the safety-related slot to the F-CPU.
3. Place the F-Proxy on the same PROFINET subnet as the F-CPU (S7-1516F-3). The F-Proxy uses its own PROFINET station name, distinct from the SIMOTION's name. If the F-Proxy inherits the SIMOTION's name, rename it explicitly, for example d425-fproxy.
4. In the F-CPU's safety program: Use the F-Proxy's PROFIsafe address assignment to address the drive's safety telegram. The PROFIsafe destination address is assigned in the drive parameters, typically via SCOUT or SINAMICS Starter, and must match the F-Proxy configuration.
5. Compile and load. Verify that the F-Proxy's PROFINET name is unique on its subnet.

Solution 4 — Renaming and Avoiding Special Characters

If topology constraints prevent separate subnets, the engineer can manually rename one of the conflicting device objects. The risk is that the runtime configuration (loaded into the SIMOTION via SCOUT) must match the project configuration (loaded into TIA Portal). Any drift causes DCP failures at startup.

Procedure

1. In TIA Portal, open the I-Device's PROFINET interface > Properties > Ethernet addresses.
2. Replace the default name (d425ma-c-a41.pnxio) with a name that contains only lowercase letters, digits, dash, and underscore. Example: d425-if1.
3. Repeat for the Device Proxy, using a different name, for example d425-if2. Note that if both objects are on the same subnet, the two names must still be unique, so this rename alone does not resolve the collision. It only cleans up the name.
4. In SCOUT, load the same names into the SIMOTION runtime. Online > Accessible Nodes > Assign PROFINET name.

This approach is cosmetic only when both objects remain on the same subnet. It does not address the underlying uniqueness violation, and it cannot produce a working configuration on its own.

Verification and Online Diagnostics

After applying the chosen solution, run the following verification steps.

Compile-time checks

1. In TIA Portal: Project tree > Devices & Networks > right-click the project > Compile > All. Confirm no duplicate-name errors.
2. Open the Project tree > Devices & Networks > Network view > PROFINET IO diagnostics. Confirm each device has a unique station name.
3. Open the Project tree > Devices & Networks > Network view > Topology view. Confirm the cabling matches the physical plant.

Online diagnostics

1. In TIA Portal: Online > Accessible nodes. The D425 appears once per configured PROFINET interface. Each instance reports the correct IP and PROFINET name.
2. In SCOUT: Online > Accessible nodes. Confirm SCOUT sees the same IP and name.
3. On the S7-1516F-3: Online & Diagnostics > PROFINET IO > Diagnostics. Confirm the SIMOTION I-Device is in AR with the F-CPU.
4. On the TP1200 Comfort: Control Panel > Network > PROFINET. Confirm the panel sees the SIMOTION via the Device Proxy slot browse.

PROFINET trace with Wireshark

For deep verification, capture PROFINET frames with Wireshark and a managed switch configured for port mirroring. Filter on the DCP identify and identify-resp frames to confirm that the device responds with the expected PROFINET station name. The expected filter:

dcp.identity or dcp.get-set

Inspect the DeviceProperties > NameOfStation field in each frame. The NameOfStation should match the name configured in TIA Portal and SCOUT exactly, including case.

Diagnostic buffer entries on SIMOTION

If the SIMOTION D425 rejects the assigned name, the diagnostic buffer records entries with the following identifiers:

Troubleshooting Matrix

Best Practices and Version Compatibility

1. Use Shared I-Device when topology allows. A single physical PROFINET line is easier to cable, easier to diagnose, and avoids the duplicate-name trap entirely.
2. Reserve separate subnets for HMI traffic when bandwidth isolation is required. Heavy HMI polling does not contend with the cyclic drive data on the IO Controller subnet.
3. Adopt a station naming convention. For SIMOTION multi-interface plants, use <device-tag>-if<n> (e.g. d425-if1, d425-if2). Avoid dots, slashes, colons, and any non-DNS-compliant characters.
4. Document the topology in the network view. Add a comment to each PROFINET interface with the subnet name, gateway, and intended IO Controller.
5. Match project and runtime names every time. After any TIA Portal change that touches PROFINET names, reload SCOUT and re-assign the name on the device, or use TIA Portal's Assign PROFINET device name function from the online menu.
6. Use the SIMOTION I-Device export with caution. Each SCOUT export generates a new GSDML revision. Install the new version before deleting the old one; otherwise the slot mapping of existing I-Device objects can break.
7. Verify the F-CPU firmware supports Shared I-Device. S7-1500 F-CPUs from firmware V2.6 onward support Shared I-Device as both IO Controller and I-Device. Earlier firmware does not.
8. Keep PROFINET device names in lowercase. Although PROFINET is case-insensitive, Linux-based firmwares (SIMOTION D4x5 V5.x onward) treat mixed case inconsistently in some DCP frames. Lowercase avoids surprises.
9. Avoid mixing I-Device and Proxy on the same subnet. This always causes the duplicate-name collision. If the architecture demands a single subnet, use Shared I-Device exclusively.
10. Document the GSDML version used. Maintain a record of the GSDML revision installed in TIA Portal alongside the SCOUT version, so that slot mapping regressions can be traced to a specific GSDML upgrade.

Version compatibility matrix

Key parameters reference

Frequently Asked Questions