Fix TIA Portal V13 IP Subnet Conflicts on TP1500 Comfort

Problem Overview

A migrated TIA Portal project targeting a SIMATIC TP1500 Comfort panel compiles cleanly in TIA Portal V11 with Runtime (OS) version 11. After the runtime is updated to OS version 13.0.1, the same project — with no changes to the IP configuration — refuses to compile and throws the following error in the compile log:

The IP address is in the same subnet as the interface X1

The original project had two PROFINET ports configured with the option "not networked" (no IP stack). The error appears immediately after the upgrade, before the panel is even downloaded. No edits were made to the port properties between V11 and V13.

This article documents the root cause, the supported solution confirmed by Siemens technical support, and the verification procedure.

Affected Products and Versions

The TP1500 Comfort is a member of the SIMATIC HMI Comfort Panel family. Its base unit always includes PROFINET port X1; additional ports (X2, X3) are exposed depending on the order code suffix (e.g. integrated second PROFINET interface, PN/PN coupler).

Root Cause Analysis

TIA Portal V13 introduced stricter validation rules for PROFINET interface configuration on Comfort Panels than V11 enforced. The rule that bites this specific project is:

Each physical PROFINET interface on a multi-port HMI must resolve to a unique IP subnet. Two interfaces whose address + mask combination lands in the same network prefix will fail compilation.

In V11 the "not networked" checkbox effectively disabled the IP routing path for that port, which meant the compiler did not perform subnet-overlap validation against it. The V13 compiler, however, treats a "not networked" port as an interface on a default address space and will flag a subnet conflict the moment a second interface is configured with any IP address.

The panel in question had both PROFINET ports configured with:

• Subnet mask: 255.255.255.248 (CIDR /29, 6 usable hosts per subnet)
• IP addresses: two distinct host addresses inside the same /29 network
• Networking: "not networked" enabled on both

Even though the two IP addresses differed, they both resolved to the same /29 network prefix under V13 validation, and the compiler rejected the project before the runtime image could be generated. V11 never performed this check, which is why the same configuration shipped for years without incident.

Solution

Siemens technical support confirmed the fix in writing. The procedure is:

1. Open the device configuration of the TP1500 Comfort in TIA Portal V13 (Project Tree → Devices → [TP1500 Comfort] → Device Configuration).
2. Select the X1 port symbol in the device view.
3. In the Properties inspector, expand PROFINET Interface [X1] → General → IP Protocol.
4. Record the IP address and subnet mask currently assigned.
5. Repeat steps 2–4 for the X2 (and X3, if present) port.
6. Change at least one interface's subnet mask so that its (IP AND mask) result differs from the other interface's network address.

Siemens support's specific recommendation in the original case was to change the subnet mask octet from 248 to 255 on the affected interface, so the mask moved from 255.255.255.248 (/29) to 255.255.255.255 (/32). A /32 mask gives the interface its own single-host network, which guarantees no overlap regardless of the partner IP. In practice, an equally clean and more conventional choice is 255.255.255.0 (/24), which produces a 254-host cell subnet and clearly separates the two PROFINET networks.

Once the masks are no longer overlapping, recompile. The error disappears and the project builds to completion.

Step-by-Step Procedure

1. Open the device configuration

• In the TIA Portal project tree, expand Devices.
• Double-click [TP1500 Comfort] to open the device view.
• The graphical representation of the panel shows the X1, X2, and (where populated) X3 ports along the bottom of the device silhouette.

2. Audit current IP settings

Click each port symbol and record:

Both interfaces resolve to 192.168.0.0/29 — this is the conflict.

3. Re-mask one interface

For X2, change the subnet mask to 255.255.255.0. The result:

Wait — that still overlaps at the network boundary because /29 is fully contained in /24. The clean fix is to either:

• Move X2 to a different physical subnet (e.g. 192.168.1.2 with mask 255.255.255.0), or
• Apply distinct /29 networks (X1 = 192.168.0.0/29, X2 = 192.168.0.8/29), or
• Apply the Siemens-recommended /32 mask (255.255.255.255) on the interface that does not need to be in a larger cell.

4. Recompile

From the menu: Compile → Software (rebuild all). Confirm the compile log no longer lists any IP/subnet errors.

Verification

After recompiling, run the following checks before downloading to the panel:

1. Compile log clean — no occurrences of IP address is in the same subnet as the interface.
2. Device view inspection — both port symbols in the device view show their IP and subnet mask without warning triangles.
3. Network scan with PRONETA (free Siemens network diagnostics tool):
   • Connect a service laptop to the engineering port.
   • Run PRONETA → Network analysis → scan the segment.
   • Confirm the TP1500 Comfort appears once per active port, with the configured IP.
4. Download and ping — download the project to the panel and use ping <panel-IP> from a service PC to confirm L3 reachability on each port.
5. PROFINET diagnostics — from TIA Portal, right-click the panel → Online & Diagnostics → PROFINET diagnostics. The device should report no configuration errors.

Subnet Mask Reference

Why the V13 Stricter Rule Exists

At the industrial-networking layer, two IP interfaces on the same physical device resolving to the same subnet creates an ambiguous L2 routing situation. When an ARP request is broadcast, both ports will answer (or one will, unpredictably), and the kernel's routing table will not have a deterministic winner. PROFINET's real-time channel (RT/IRT) is particularly sensitive to this, because deterministic forwarding depends on knowing exactly which physical port owns a given MAC.

V11 was permissive because the original "not networked" UI state was conceived as a benign configuration placeholder — the panel's IP stack effectively skipped validation for that port. As Comfort Panels grew in capability and customers started routinely using both X1 and X2 for live networks (e.g., one to the PLC, one to a SCADA gateway), Siemens tightened the validation in V13 so that misconfigurations were caught at compile time rather than at commissioning.

Best Practices to Prevent Recurrence

1. Document port roles at project creation. Decide up front: which port talks to the controller, which talks to the engineering / MES layer, which is unused.
2. Always assign a real subnet mask to every port. Avoid "not networked" as a permanent placeholder; treat it as a temporary state during initial commissioning only.
3. Run a dry compile before upgrading TIA Portal. Copy the project to a sandbox, upgrade, and recompile. Surface every V13 enforcement change before touching the live project.
4. Use PRONETA for pre-commissioning verification — it scans PROFINET segments and reports duplicate IPs and overlapping subnets regardless of TIA Portal version.
5. Track firmware/runtime versions explicitly. Store the OS image version in the project documentation. V11 → V13 is a non-trivial jump; expect behavior changes in graphic handling, scripting, and network validation.
6. Engage Siemens support early when a migration breaks an unchanged configuration. The original case was resolved with a single Siemens support contact in one session.

Related Configuration Checks

Diagnostics Quick Reference

Frequently Asked Questions