Resolving CPU315-2 PN/DP Missing in STEP 7 V5.4 SP5 Wizard

The Siemens SIMATIC S7-300 CPU 315-2 PN/DP with order number (MLFB) 6ES7 315-2EH14-0AB0 is a direct successor to 6ES7 315-2EH13-0AB0. STEP 7 V5.4 SP5 was released before the 2EH14 hardware variant entered mass production, so the New Project Wizard and the underlying hardware catalog do not list the newer MLFB. The wizard silently filters catalog entries that the installed STEP 7 service pack cannot fully configure, which is why a technician creating a fresh project only sees the older 2EH13 (and even fewer 2EH14 entries) and concludes that the CPU is unsupported. The CPU is in fact supported, but only when paired with STEP 7 V5.5 or higher, or with the older 2EH13 firmware revision under STEP 7 V5.4 SP5.

This article explains the compatibility window, identifies the exact firmware threshold (V3.2.7) that decides whether V5.4 SP5 or V5.5 is required, and documents three field-proven recovery paths: substitute the predecessor MLFB, manually insert the 2EH14 from the hardware catalog, or upgrade the engineering software.

Problem Details

Symptom

When opening File > 'New Project' Wizard in SIMATIC Manager with STEP 7 V5.4 SP5 installed, the CPU selection list does not include the SIMATIC S7-300 CPU 315-2 PN/DP variant 6ES7 315-2EH14-0AB0. The closest entries visible are:

• 6ES7 315-2EH13-0AB0 — CPU 315-2 PN/DP, 256 KB work memory, 1st interface PROFINET, 2nd interface DP master/slave.
• Older 6ES7 315-2xx1x-0AB0 variants without PROFINET (DP only).

The CPU physically present on the rack, when identified through PLC > 'Accessible Nodes' (Accessible Nodes) or via PG/PC interface, reports the 2EH14 MLFB and firmware V3.x, but SIMATIC Manager refuses to add it to a freshly created project.

Affected Environment

Identification Steps

1. Connect the PG to the CPU's MPI/DP or PROFINET interface.
2. In SIMATIC Manager, choose PLC > 'Accessible Nodes'.
3. Read the Order Number field on the diagnostic node that appears.
4. Open PLC > 'Module Information' > 'Diagnostic Buffer' to capture the firmware release. The line beginning with Firmware reports something like V3.2.7 or V3.3.0.

Root Cause Analysis

STEP 7 hardware support is delivered through the Hardware Catalog (HW Config catalog tree) and through Hardware Support Packages (HSP) loaded into the project. Each Service Pack of STEP 7 extends the catalog with MLFBs released up to that point in time. The catalog is bound to STEP 7 build, not to firmware:

• STEP 7 V5.4 SP5 was published before the 6ES7 315-2EH14-0AB0 became generally available, so the MLFB is not in its baseline catalog.
• The threshold V3.2.7 is the firmware revision where Siemens restructured the module-internal GSD/object model. STEP 7 V5.4 SP5 can read firmware up to V3.2.6 with the older catalog entry, but cannot reliably describe modules starting with V3.2.7 because the parameter image no longer matches what the wizard expects.
• STEP 7 V5.5 (and its service packs up to and beyond SP4) added catalog entries for both the 2EH13 and the 2EH14, plus the F-Configuration Pack release line that handles safety projects.

Because the New Project Wizard is a convenience dialog that scans the catalog for currently-installable CPUs, an MLFB absent from the catalog simply never appears as a selectable option. The wizard does not perform a feature negotiation — it only lists MLFBs whose catalog descriptions were registered when STEP 7 was installed.

Direct-Successor Rule

Siemens permits configuring a newer CPU with older STEP 7 only when the CPU is a direct successor of an MLFB already present in the installed catalog. The 2EH14 is the direct successor of the 2EH13, so the following is theoretically allowed:

1. Insert a 6ES7 315-2EH13-0AB0 from the V5.4 SP5 catalog.
2. Right-click the CPU slot > 'Replace Object' > 'CPU 315-2 PN/DP 2EH14'.

The replacement succeeds only when the target firmware is below V3.2.7. With V3.2.7 or higher, STEP 7 V5.4 SP5 raises Error 13:0107 — configuration data not suitable for target firmware during download or online comparison.

Compatibility Matrix

Solution Paths

Three field-proven recovery paths exist. Choose based on your operational constraints (downtime tolerance, software-update policy, available licenses, and whether the firmware is below or above V3.2.7).

Path A — Use the Predecessor MLFB 6ES7 315-2EH13-0AB0

Applicable when the on-site CPU is the older 2EH13, OR when you can temporarily downgrade the firmware on a 2EH14 to a revision below V3.2.7. STEP 7 V5.4 SP5 supports the 2EH13 with the full feature set, and projects written against it can be downloaded without errors.

1. Open the New Project Wizard and select 6ES7 315-2EH13-0AB0 from the CPU list.
2. Complete the wizard with your rack/Slot-2 I/O configuration.
3. In HW Config, verify the PROFIBUS and PROFINET interface settings match the physical wiring.
4. Download the project to the CPU.

Path B — Manually Insert the 2EH14 From the Catalog

Applicable when you must keep the 2EH14 MLFB and have firmware below V3.2.7. The New Project Wizard hides MLFBs not in the default catalog, but the catalog tree itself in HW Config often contains additional entries that the wizard filter omits.

1. Create a new project and open HW Config.
2. In the hardware catalog tree, navigate to SIMATIC 300 > CPU 300 > CPU 315-2 PN/DP > 6ES7 315-2EH14-0AB0.
3. If the entry is absent, install the latest Hardware Support Package (HSP) for V5.4 SP5 from the Siemens support site. HSPs extend the catalog without changing the STEP 7 build number.
4. Drag the 2EH14 onto Slot 2 of rack 0.
5. Save, compile, and download.

If the entry is still missing after the HSP install, the installed HSP set is older than the MLFB revision — proceed to Path C.

Path C — Upgrade STEP 7 to V5.5 (Recommended)

Applicable when firmware is at or above V3.2.7, when safety projects use S7 Distributed Safety, or when the plant standardization policy requires modern engineering software.

1. Order or download STEP 7 V5.5 with the latest Service Pack (SP4 or higher at the time of writing).
2. If the project includes F-CPU safety logic, also install the matching F-Configuration Pack. The S7 Distributed Safety V5.4 SP5 → V5.5 SP13 migration path is officially supported as long as the project was last compiled in V5.4 SP5. Open the project in V5.5, recompile, and verify all F-block signatures before downloading to a productive F-CPU.
3. Open the upgraded project in SIMATIC Manager V5.5. The New Project Wizard now lists both the 2EH13 and the 2EH14.
4. Replace any inserted placeholder CPUs (from Path B) with the proper 2EH14 catalog entry.

Step-by-Step Procedure — Verify Replacement CPU Compatibility

Use this procedure when the on-site CPU is the 2EH14 with firmware at or above V3.2.7 and you must decide whether Path A or Path C is the shortest recovery.

1. Connect the PG to the CPU PROFINET interface (X1) or MPI/DP (X2) using the PG cable 6ES7901-0BF00-0AA0 (PROFINET) or 6ES7901-0BB00-0AA0 (MPI/DP).
2. Open SIMATIC Manager V5.4 SP5, choose PLC > 'Accessible Nodes'.
3. Confirm the order number shows 6ES7 315-2EH14-0AB0.
4. Open PLC > 'Module Information' > 'Diagnostic Buffer'.
5. Find the firmware entry. If the firmware string reads V3.2.6 or lower, Path A is feasible after a clean replace-object operation. If it reads V3.2.7 or higher, Path A is blocked and you must use Path C.
6. Capture the diagnostic buffer to a text file (Save as...) before any firmware action, so you have a pre-change baseline.

Step-by-Step Procedure — Manually Replace the CPU in HW Config

1. Open the existing STEP 7 V5.4 SP5 project.
2. Open HW Config and double-click the CPU 315-2 PN/DP entry currently on Slot 2.
3. From the Order Number dropdown, choose the 2EH14 variant, then click OK.
4. STEP 7 prompts to load the new catalog description. Accept.
5. Save & Compile (Station > Save and Compile).
6. If the project previously had the 2EH13 and the replace operation succeeded, the configuration is now consistent with the on-site hardware. Download and run.
7. If Save and Compile returns error 13:0107, the firmware on the physical CPU is at or above V3.2.7 and V5.4 SP5 cannot host the new configuration. Switch to Path C.

Step-by-Step Procedure — Upgrade Engineering Software to STEP 7 V5.5

1. Back up the V5.4 SP5 project to a network share or removable media.
2. Install STEP 7 V5.5 on the PG. The installer accepts V5.4 as the prerequisite.
3. Apply the latest Service Pack (SPx). Read the SP readme for HSPs that must be installed alongside.
4. If safety programs are present, install the S7 Distributed Safety V5.5 option pack and the matching F-Configuration Pack. Projects compiled in V5.4 SP5 can be opened and recompiled without losing F-signatures.
5. Open the archived project in V5.5. The Catalog tree now shows 6ES7 315-2EH14-0AB0.
6. Use CPU > 'Replace Object' on Slot 2 to swap the placeholder 2EH13 for the 2EH14 if needed.
7. Compile, download, and verify against the on-site CPU. The diagnostic buffer should no longer raise the 13:0107 event.

For the official Siemens documentation on the safety migration path, refer to Migrating projects from S7 Distributed Safety V5.4 SP5 to STEP 7 Safety Advanced.

Firmware Handling — Up or Down

The firmware threshold V3.2.7 is the deciding factor. Two firmware-related operations are common in the field:

• Update a 2EH13 with newer firmware: allowed and supported through the SIMATIC firmware-update tool. After the update, the project may need to be recompiled with a STEP 7 version that knows about the new firmware.
• Downgrade a 2EH14 firmware to <V3.2.7: technically possible through the firmware-update tool, but Siemens does not officially support downgrading an S7-300 CPU. Field reports show mixed results and a residual risk that the CPU enters a non-recoverable state. Only perform a downgrade in a lab or off-line environment, never on a productive plant.

Verification

After applying any of the three paths, perform the following verification sequence:

1. Catalog consistency: In HW Config, the Slot 2 module must display the same MLFB that is printed on the physical CPU front panel. Mismatch indicates the wizard or replace-object step did not complete.
2. Online compare: PLC > 'Compare' > 'Online/Offline' must report No differences for all configuration blocks.
3. Download: A clean download without 13:0107 or 13:010B errors confirms the catalog and firmware agree.
4. Diagnostic buffer: PLC > 'Module Information' > 'Diagnostic Buffer' should be empty of start-up errors. A repeating Module incorrect / module not known entry means the catalog description still does not match the firmware.
5. Cyclic scan: Place the CPU in RUN. The mode selector should show a steady green RUN LED, with the SF (group error) LED dark and the BF (bus fault) LEDs dark on both interfaces.
6. PROFINET name assignment: For PN/DP operation, verify the PROFINET device name resolves on the controller side using Accessible Nodes or a third-party PROFINET tool. A missing device name is the most common first-day failure on PROFINET systems.

Troubleshooting Matrix

Engineering Notes & Field Caveats

• The direct-successor rule is enforced by the catalog, not by STEP 7. Skipping a generation (e.g., replacing a 2EH13 directly with a 2EH15 if such existed) is blocked even when the user interface appears to allow the drag.
• The CPU 315-2 PN/DP supports both PROFINET IO controller and PROFINET IO device modes on the X1 interface; the older 2EH13 firmware revisions had a limited IO-device implementation. Projects that rely on PN-device functionality should prefer Path C (V5.5) regardless of firmware level.
• The X2 interface on both 2EH13 and 2EH14 is a combined MPI/PROFIBUS-DP master/slave port. DP master operation requires the PROFIBUS DP option in HW Config; this option is present in V5.4 SP5 but its parameters were extended in V5.5.
• STEP 7 V5.4 SP5 does not support TIA Portal project import. If the long-term migration target is TIA Portal (V13 and above), the upgrade to V5.5 is a necessary stepping stone because the V5.5 SPx project archives are what TIA Portal's converter accepts.
• Older 2EH13 CPUs shipped with firmware V2.x. The V3.x line introduces new PN diagnostics that V5.4 SP5 displays as "unknown diagnostic" entries. The diagnostic itself is harmless; the warning is purely a UI quirk that disappears with V5.5.

Related Components Often Missed in the Same Migration

When upgrading engineering software to address the CPU 315-2 PN/DP issue, also verify the following related components in the rack. They are common sources of side-effect failures during a V5.4 SP5 → V5.5 migration:

• CP 343-1 (6GK7 343-1EX30) — PROFINET IO controller; benefits from the same firmware and HSP updates.
• IM 151 / IM 153 (PROFIBUS / PROFINET interface modules for ET 200S / ET 200M) — newer revisions require the matching GSD/GSDML.
• SM 334 analog I/O — calibration constants are stored per channel; backup before any CPU replace.
• F-CPU safety blocks — recompile after V5.5 upgrade; re-sign with the new F-Configuration Pack.

Frequently Asked Questions