Troubleshooting C240PN to IM151-3PN PROFINET Communication Faults

PROFINET communication failures between a Siemens SIMOTION C240PN motion controller and an ET200S IM151-3PN distributed I/O station are a classic commissioning fault pattern. The symptom usually surfaces inside TIA Portal V13 SP1 Update 9 as a "Device unknown" status, mismatched online/offline configuration, and persistent SF (System Fault) LEDs on the IM and its I/O modules even after the station name has been written successfully through the accessible nodes view.

This reference walks through the documented root cause, the diagnostic procedure to isolate it, and the exact hardware configuration and download sequence that resolves the fault on C240PN firmware V4.4 HF6 with IM151-3PN firmware V7.0.5 and GSD/GSDML V7.0.

1. Problem Details

1.1 System Under Test

• Controller: SIMOTION C240PN, MMC card labeled V4.4 HF6
• Engineering software: TIA Portal V13 SP1 Update 9, with Scout TIA plug-in
• PROFINET IO Device: ET200S IM151-3PN (6ES7 151-3BA23-0AB0 family), firmware V7.0.5
• GSD file in catalog: V7.0 (compatibility with V7.0.5 firmware verified)
• Sub-modules inserted in IM151-3PN:
  • PM-E power module: 6ES7 138-4CA01-0AA0
  • DI digital input: 6ES7 131-4BD01-0AA0 (qty 2)
  • AI analog input: 6ES7 134-4FB01-0AB0 (qty 1)
• IP subnet: 192.168.0.0/24 (192.168.0.XXX addressing)
• Connection interface used during test: X11 (Ethernet service/engineering port on C240PN)

1.2 Observed Symptoms

1. "Device unknown" status in the TIA Portal network view for the IM151-3PN, even after assigning the PROFINET device name manually through Accessible devices.
2. Online/offline mismatch icon between the C240PN controller and the IM151-3PN station in the network view.
3. Persistent warning on every "Go online" operation:

   "Going online: the HW configuration of the PLC_1 was changed but it was not compiled and loaded yet. The shown diagnostics is possibly inconsistent or wrong."

4. SF LEDs active on the PM-E module and on the AI module, even though the PM-E should be in the cleared state once PROFINET name assignment and AR (Application Relationship) establishment succeed.
5. Accessible nodes view does see the IM151-3PN, but the diagnostic buffer reports an inconsistent or wrong result after going online.

1.3 What Does NOT Trigger the Fault

• Running TIA Portal / Scout TIA in a virtual machine is not a root cause; tests confirm virtualized installations reproduce and resolve the fault identically.
• Windows 10 as the engineering OS is not a confirmed root cause when the procedure in Section 5 is followed.
• The minor GSD/firmware mismatch (GSD V7.0 used against IM151-3PN firmware V7.0.5) is not the source of the failure.

2. Root Cause Analysis

The root cause is a mismatch in the project image stored on the SIMOTION C240PN relative to the configuration the TIA Portal engineering station is trying to download. Three contributing factors converge to produce the visible symptoms:

2.1 Incorrect Catalog Folder for GSD/GSDML Devices

When the IM151-3PN is inserted from the Distributed I/O > ET200S catalog folder, TIA Portal instantiates the device from its internal HSP / hardware catalog representation, not from the installed GSD/GSDML file. This is a known subtle point: catalog entries are not GSD files. The proper location for GSD- or GSDML-based devices is:

Hardware catalog > Other field devices > Additional Field Devices > PROFINET IO > ET200S

If the device is taken from the Distributed I/O tree, the GSDML referenced by the catalog entry may not match the IM151-3PN firmware that physically responds on the wire, producing "Device unknown" once the AR is attempted.

2.2 Download Path Confusion Between TIA Portal and Scout TIA

For a SIMOTION controller hosted inside TIA Portal, the canonical download path for hardware configuration is the Scout TIA plug-in, not the TIA Portal "Download to device > Hardware configuration" command. When the hardware is loaded through the TIA Portal path, the TIA Portal project image and the Scout TIA project image on the MMC can desynchronize. The controller then returns the persistent warning:

"HW configuration of PLC_1 was changed but it was not compiled and loaded yet."

This is the dominant cause of the SF LEDs on the PM-E and the AI module: the AR establishment partially succeeds for station discovery but the slot configuration delivered to the head module does not match what the inserted I/O modules can accept.

2.3 Non-DNS-Compliant PROFINET Station Name

PROFINET station names must follow DNS naming rules (RFC 1123) — letters, digits, and hyphens only, no underscores, no leading digits in the label. A station name written to the IM that violates this rule is accepted by some tools but rejected by the controller's AR establishment, again producing "Device unknown" in the diagnostic buffer even when accessible nodes can ping the device.

3. Diagnostic Procedure

Before changing anything, isolate each factor. The recommended sequence takes about 10 minutes on a fully wired bench.

3.1 Step 1 — Confirm Accessible Nodes

1. Open TIA Portal project, expand the project tree, right-click the C240PN and select Go online > Accessible devices.
2. Confirm the IM151-3PN is listed with its MAC and the station name you assigned.
3. If the device is missing, verify X11 cable, subnet mask (255.255.255.0), and that PG/PC interface is set to the correct Intel/Realtek adapter.

3.2 Step 2 — Verify the GSD/GSDML Origin

1. Right-click the IM151-3PN device in the network or device view, choose Properties > General > Catalog Information.
2. Confirm the source line states GSDML-Vx.x-... rather than HSP or internal catalog.
3. If the catalog line does not reference a GSDML, delete the device and re-insert it from Additional Field Devices.

3.3 Step 3 — Inspect Online/Offline Difference

1. Open the Topology view of the PROFINET subnet.
2. Right-click the IM151-3PN port and select Compare offline/online.
3. Examine the diff report. Typical mismatches reported in this scenario:
   • Slot 1 PM-E expected, slot 1 empty online
   • Slot 2 DI expected, slot 2 different article number online
   • Slot 4 AI expected, slot 4 unsupported module online

3.4 Step 4 — Read the SIMOTION Diagnostic Buffer

1. In Scout TIA, connect to the C240PN, open Target system > Diagnostics buffer.
2. Filter for entries tagged PROFINET IO and Station failure.
3. Record the slot mismatch and the expected vs. actual article number reported in the buffer.

3.5 Step 5 — Validate the Station Name

1. In Accessible devices, click the IM151-3PN row, then Flash LED to physically verify you are talking to the correct head module.
2. Read the assigned PROFINET name. If it contains underscores, leading digits, or non-ASCII characters, rewrite it to a DNS-compliant form such as im151pn or et200s-line1.

4. Affected Versions and Compatibility Matrix

Component	Tested Version	Compatible Versions	Notes
SIMOTION C240PN	V4.4 HF6 (on MMC)	V4.4 HFx, V4.5	Scout TIA V4.4 HF6 confirmed working in replication
IM151-3PN head module	Firmware V7.0.5	V7.0.x, V8.x (ET200S)	6ES7 151-3Bx2x-0AB0 family
GSDML installed in TIA	V7.0	V7.0.x	Minor mismatch with V7.0.5 firmware tolerated
TIA Portal	V13 SP1 Update 9	V13 SP1 Upd 4..9, V14 SP1	Scout TIA plug-in required for SIMOTION
Scout TIA	V4.4 HF6	V4.4 HFx	Must match the MMC firmware major.minor
Engineering PC OS	Windows 7 / 10	Win 7, Win 10, VM-isolated Win 7	Not a root cause

5. Solution — Step-by-Step Procedure

The fix has three parts, in order: (A) put the project on a clean baseline, (B) download through Scout TIA, (C) verify the AR is established and SF LEDs clear.

5.1 Part A — Clean Baseline on the C240PN

1. Power down the C240PN.
2. Set the mode selector to MRES and hold it while powering back on.
3. Wait until the STOP LED is on, then return the selector to STOP.
4. (Optional but recommended) Delete user data on the MMC: in Scout TIA, Target system > Delete user data on card. This guarantees a clean configuration memory before the next load.

5.2 Part B — Correct Download Sequence

1. In TIA Portal, in the project tree, compile the hardware configuration:

   PLC_1 > right-click > Compile > Hardware (Compile all)

2. Do not use Download to device > Hardware configuration from TIA Portal. Switch to Scout TIA.
3. In Scout TIA, go online with the C240PN (X11 interface).
4. Click Save and compile, then Target system > Load > Download project to target system. Accept the download prompt.
5. Once download completes, go offline in Scout TIA.
6. Return to TIA Portal and go online. The persistent "HW configuration changed but not compiled and loaded" warning should no longer appear.

5.3 Part C — Station Name and AR Verification

1. Use a DNS-compliant station name for the IM151-3PN, e.g. im151pn or et200s-line1.
2. From TIA Portal Accessible devices, write the new name to the IM head module.
3. Compile and download the project again (Part B) so the C240PN's IO controller knows the new name.
4. Wait for the IM151-3PN BF LED to extinguish. The SF LED on the PM-E and on the AI module should clear within 3-5 seconds of AR establishment.

6. Verification

After the fix, perform the following four checks. All four must pass before the station is signed off.

6.1 Check 1 — Diagnostic Buffer Is Clean

1. In Scout TIA, open the diagnostic buffer.
2. Confirm the most recent PROFINET entry is Station return with the IM151-3PN station name and IP.
3. No Station failure, Slot mismatch, or Device unknown entries should remain.

6.2 Check 2 — LED Status

LED	Expected State	If Not
IM151-3PN BF (bus fault)	OFF	Name/IP mismatch — re-assign name, recompile
IM151-3PN SF (system fault)	OFF	Slot configuration mismatch — recheck module order
IM151-3PN ON	Green, steady	No 24 V supply to PM-E
PM-E SF	OFF	Station not yet in AR — wait or re-load
AI module SF	OFF	Module pulled or wrong article number in slot
DI module SF	OFF	Same as AI

6.3 Check 3 — Online Slot View

1. In TIA Portal, with the C240PN online, right-click the IM151-3PN and select Online & diagnostics.
2. Open the Module information tab. Slots 1..4 should display:
   • Slot 1: PM-E (6ES7 138-4CA01-0AA0)
   • Slot 2: DI (6ES7 131-4BD01-0AA0)
   • Slot 3: DI (6ES7 131-4BD01-0AA0)
   • Slot 4: AI (6ES7 134-4FB01-0AB0)
3. No slot should display a red status bar or Wrong module.

6.4 Check 4 — Cyclic I/O Is Updating

1. In Scout TIA, open a watch table on the SIMOTION I/O mapping.
2. Force a digital input and confirm the corresponding I-address flips within the PROFINET update cycle (default 1 ms).
3. Read the AI raw value and confirm it tracks a 4-20 mA source.

7. Hardware and Module Reference

7.1 IM151-3PN Head Module

Parameter	Value
Article number (typical)	6ES7 151-3BA23-0AB0 / -3BA23-0AB1
PROFINET interface	2-port switch, integrated
Update time, min	1 ms
Max number of I/O modules	63 (depends on power budget)
Supported GSDML	V7.0, V7.0.5, V8.x
Diagnostic interrupts	Yes (pull / plug, module failure, channel fault)

7.2 PM-E Power Module 6ES7 138-4CA01-0AA0

Parameter	Value
Function	Electronic load power supply for downstream modules
Nominal input	24 V DC
Output voltage	24 V DC to backplane
Max load current	5 A
Diagnostic	SF LED (group fault), 24 V OK LED

7.3 DI Module 6ES7 131-4BD01-0AA0

Parameter	Value
Channels	4 DI (PNP, sourcing)
Nominal input voltage	24 V DC
Input delay, typ.	3 ms (0.5 / 3 / 15 / 20 ms configurable)
Diagnostics	Wire break (per channel, optional)
Module width	15 mm

7.4 AI Module 6ES7 134-4FB01-0AB0

Parameter	Value
Channels	2 AI (differential / U / I / RTD / TC)
Resolution	15 bits + sign
Conversion time per channel	≤ 20 ms (depends on integration time)
Input ranges	±10 V, 0..10 V, ±5 V, 0..5 V, 1..5 V, 0/4..20 mA, RTD Pt100 / Pt1000, TC type J/K
Diagnostic	SF LED, overflow / underflow, wire break, short circuit

8. Commissioning Workflow Diagram

9. Common Pitfalls and Edge Cases

9.1 Mixing GSD Versions Across the Same Subnet

If your project contains two IM151-3PN stations, both with different firmware revisions, install both GSDML files. TIA Portal will let you use the wrong GSDML for the wrong station if the article number is the same — the resulting AR is accepted by the controller but rejected by the head module at the slot level.

9.2 Long Station Names with Dots and Underscores

PROFINET names are labels inside a single DNS zone. Allowed characters: a-z, A-Z, 0-9, hyphen. Underscores produce inconsistent behavior across SIMOTION firmware revisions: V4.4 HF6 may accept, V4.5 rejects, V4.3 always rejects.

9.3 X11 vs X12 Service Interfaces

On C240PN, the X11 port is the engineering/service port. The X12 port is the PROFINET IO controller port. Accessible devices must be performed through X11; the controller's own IO AR is established on X12. If you mix them, the controller reports its own name as accessible and the IM never returns from "Device unknown".

9.4 Partial Slot Configuration After Pull/Plug

Pulling a module while online and re-inserting a different module of the same width (for example, swapping a DI for another DI) updates the physical slot but not the configured slot map. Re-do Part B (Scout TIA download) to push the new configuration to the controller's image.

9.5 Compare Offline/Online Always Saves an Additional File

The message "Offline/online comparison completed successfully. Result is saved in additional files" is informational, not an error. The diff XML lives next to the project file. TIA Portal opens it from Project tree > Common data > Logs.

10. Diagnostic Buffer Entry Index

When the controller logs PROFINET events, the following indexes are useful for filtering the Scout TIA diagnostic buffer:

Event ID	Meaning	Recovery Hint
0x0102	Station return (AR up)	None — informational
0x0103	Station failure (AR down)	Check cable, name, slot
0x0104	Slot mismatch	Reconcile hardware catalog with physical module
0x0105	Device unknown	GSDML not installed or wrong name
0x0106	Module pulled	Reinsert or recompile
0x0107	Module inserted (wrong)	Compare with configured article number

11. Alternative Tools and Migration Paths

11.1 Scout Standalone (Without TIA Portal)

If the TIA Portal > Scout TIA round trip continues to fail, the project can be migrated to Scout Standalone (the pre-TIA variant of Scout). The project can be opened, downloaded, and run, but the WinCC HMI integration must be re-built using SIMATIC WinCC flexible or TIA WinCC separately. This is a fallback, not a first choice, because it splits the engineering environment.

11.2 TIA Portal V14 / V15 / V16

Newer TIA Portal versions are more tolerant of the catalog/HSP/GSDML issue, but the Scout TIA is still the canonical download path. If the customer is willing to upgrade the MMC firmware, the V4.5 SIMOTION runtime is a long-term supported path.

11.3 PROFINET Network Diagnostics with Primary Setup Tool

The Siemens Primary Setup Tool (PST) can be used to assign the IM151-3PN station name outside of TIA Portal. This is helpful when the SIMOTION controller is not yet fully booted but you need to prepare the head module for AR establishment.

12. Related Siemens Documentation

• SIMOTION C240PN Operating Instructions — hardware description, X11/X12 port usage, MRES sequence.
• ET200S IM151-3PN Manual — pinout, GSDML versions, diagnostic LED meanings.
• TIA Portal V13 SP1 Update 9 Release Notes — known issues and fixes for PROFINET IO commissioning.
• Scout TIA V4.4 HF6 Readme — canonical download path for SIMOTION hardware configuration.
• PROFINET Commissioning and Diagnostics — Application Note for station name rules, AR establishment, and the offline/online compare workflow.