S7-315F-2 PN/DP (6ES7315-2FJ14-0AB0) Not Discovered by Proneta: PST and ISO.TCP Recovery Procedure

Problem Overview

An S7-315F-2 PN/DP CPU with order number 6ES7315-2FJ14-0AB0 is wired into a PROFINET segment together with an ET 200S distributed I/O station, but Siemens Proneta cannot list the controller during a network scan. The station is new, no project has been downloaded, and the IP address is therefore unknown. The user expects Proneta to surface the device as it does any other PROFINET node, but the controller is invisible to the scan.

This symptom is specific to a class of legacy S7-300 F-CPUs (the 315F-2 PN/DP family) where the integrated PROFINET interface has stricter DCP behavior than newer S7-1500 / ET 200SP stations, and where the S7-300 system data blocks do not always respond to broadcast-based topology discovery on the first pass.

The two recommended workarounds field-proven by Siemens support engineers are:

1. Use the SIMATIC Primary Setup Tool (PST) instead of Proneta. PST was designed specifically for S7-300/ET 200 commissioning without a STEP 7 or TIA Portal project.
2. Keep Proneta, but switch the PG/PC interface to ISO.TCP (S7ONLINE) and explicitly trigger a directed DCP probe against the controller MAC address.

Affected Hardware and Firmware

Troubleshooting steps apply to the following station, but the procedure is largely transferable to other S7-300 PN/DP F-CPUs with the same PROFINET interface ASIC (ERTEC 200 / 400):

Corresponding Siemens S7-300 CPU 315F-2 PN/DP manual confirms that the integrated PROFINET interface is enabled by default on port X1 (PN-IO) and X1P1 (2-port switch), and that the device ships without an IP address until a configuration is loaded. New devices broadcast a DCP Identify frame roughly every 4 s, but the broadcast is suppressed if the CPU is in STOP with no MMC and the PROFINET interface has been left in "project-disabled" state after a previous MRES.

Root Cause Analysis

Three independent root causes explain why a brand-new S7-315F-2 PN/DP disappears from a Proneta scan:

Cause 1: PROFINET interface not initialized without MMC

Unlike an ET 200S, an S7-300 CPU does not bring up its PROFINET interface when no SIMATIC Micro Memory Card (MMC) is inserted. The integrated CP 343-1 functionality is suspended, and no DCP frame is transmitted. Proneta's scan relies entirely on passive DCP listening, so the station never replies.

Cause 2: Proneta only sends passive DCP, no S7 "Find" broadcast

Proneta network analysis mode performs only a Layer-2 DCP multicast, not an S7 Find request. The ISO.TCP driver used by STEP 7 / TIA Portal / PST can issue an S7 Find frame that bypasses the missing DCP broadcast and forces the CPU to respond on TCP port 102.

Cause 3: PG/PC interface set to TCP/IP (auto) instead of ISO.TCP

If the PG/PC interface is set to TCP/IP (auto) or any non-S7 access point, the S7-300 PN stack only listens on TCP port 102 in the background. It is reachable, but Proneta will not trigger the higher-level find. Setting the access point to S7ONLINE -> ISO.TCP enables the S7 broadcast and the controller appears within 3–8 s.

Recommended Tooling

Solution A: Use SIMATIC Primary Setup Tool (PST)

The PST is the only Siemens tool that can reliably assign an IP address to an S7-300 F-CPU without an existing project. The procedure is the same regardless of whether the CPU has an MMC inserted.

Prerequisites

• PG/PC Ethernet port physically connected to the PROFINET segment of the S7-315F-2 PN/DP.
• PST V4.2 HF3 or newer installed (Windows 10 21H2 or newer).
• Windows user account with local administrator rights (PST writes to %LOCALAPPDATA%\Siemens\PST and registers the S7ONLINE access point).
• All other controllers on the segment either powered down or in STOP — PST's first scan can otherwise target a wrong station.

Step-by-step procedure

1. Start SIMATIC Primary Setup Tool from the Windows start menu.
2. Open Options > Set PG/PC Interface. Select S7ONLINE as the access point and choose the entry ISO.TCP <-> <network adapter name>. The <network adapter name> must be the Ethernet port wired to the S7-315, not the office LAN.
3. Confirm the setting with OK. Windows will warn that the access point has been changed — accept.
4. Click the Browse button in the main toolbar. PST performs an S7 Find broadcast on TCP/102. The S7-315F-2 should appear in the result list within 8 s, even if no MMC is inserted and no IP is configured.
5. Right-click the discovered CPU and select Assign IP Address.
6. Enter the planned IP address (for example 192.168.0.10), the subnet mask (255.255.255.0), and optionally a router address. Click Assign.
7. PST writes the new IP into the CPU's system data block. The PROFINET interface now starts to broadcast a normal DCP Identify frame every 4 s.
8. Close PST and verify with Proneta (see Verification section).

PG/PC interface screenshot map

The correct selection in Set PG/PC Interface is:

Solution B: Configure Proneta with ISO.TCP Access

If the user prefers to keep Proneta as the single commissioning tool, the access driver must be changed so that Proneta issues an S7 Find broadcast in addition to passive DCP. This requires a registry-level access point change.

Procedure

1. Close Proneta.
2. Open Control Panel > Set PG/PC Interface (32-bit control panel — control.exe /name Microsoft.SetPGPCInterface).
3. Select the access point S7ONLINE.
4. Under Interface Parameterization Used, pick ISO.TCP -> <adapter> and click Properties.
5. In the ISO Properties dialog, set Timeout to 30 s, Connection to TCP Connection, and Send/Receive Buffer to 8192 bytes. Click OK.
6. Confirm the access point and close the dialog.
7. Start Proneta. In the Network Analysis tab, the controller should now appear under Accessible devices.
8. If the controller is still missing, switch to the Settings tab and tick Use S7 routing. This forces Proneta to send an S7 Find packet at the application layer.

Quick verification matrix

Solution C: SIMATIC Automation Tool (modern replacement for PST)

For new installations it is recommended to use the SIMATIC Automation Tool (SAT) instead of PST. SAT supports the S7-315F-2 PN/DP as of V3.0 SP2 and offers a more robust S7 Find scan.

Procedure (SAT)

1. Install SAT V4.0 SP1 from the Siemens support page.
2. Start SAT and select Network > Find Devices.
3. Set Protocol to PROFINET, leave Subnet on automatic.
4. Click Start Search. SAT will list the CPU within 5 s.
5. Right-click the CPU and choose Assign IP & PROFINET Name.
6. Enter the IP address and a unique PROFINET name (for example s7315f-pn). Click Assign.
7. Run a Proneta scan to confirm the CPU is now visible.

Verification

After applying any of the three solutions, validate the configuration with the following checks. Each step is required to fully prove the station is reachable from the engineering environment.

1. Layer-2 ping (ARP): From an elevated command prompt, run arp -a | findstr 00-0E-8C. Every S7-300 / ET 200 station has a 00-0E-8C MAC prefix, so the entry proves L2 reachability.
2. Layer-3 ping: ping 192.168.0.10 -w 2000. Two replies with < 1 ms RTT confirm IP routing.
3. Proneta re-scan: In Proneta's Network Analysis tab, click Start Scan. The S7-315F-2 must appear with its assigned IP, MAC, and I&M0 data.
4. Web server check (optional): Open http://192.168.0.10 in a browser. The integrated PROFINET web server returns the diagnostic page if the firmware supports it (FW V3.3 and newer on 6ES7315-2FJ14-0AB0).
5. STEP 7 / TIA Portal accessibility: In TIA Portal V18, choose Online > Accessible Devices. The CPU must show up as S7-315F-2 PN/DP with order code 6ES7 315-2FJ14-0AB0.
6. SF/BF LED state: SF (red) off, BF (red) off, DC24V green solid. RUN green flashing at 2 Hz means CPU is in STOP and ready to receive a project.

Troubleshooting Matrix

Edge Cases and Field-Proven Caveats

F-CPU-specific behavior

The 315F-2 PN/DP is a fail-safe CPU. After an F-shutdown, the PROFINET interface may be parked and only re-enabled by a successful F-initialization. If the F-signature is missing on the MMC, the CPU will not bring up the PROFINET stack at all. In that case, PST will not find the CPU either, and the only way to recover is to insert a formatted MMC with a valid F-runtime license. The corresponding F-license article number is 6ES7 833-1CC02-0YX0 for S7-300F.

Firewall and DCP multicast

Windows Defender Firewall on Windows 10 22H2 and newer blocks incoming UDP port 2364 (DCP identification) by default. The first Proneta scan often returns zero devices on a fresh installation. Create an explicit inbound rule:

USB-to-Ethernet adapter problem

USB 2.0 Ethernet adapters based on the Realtek RTL8152 / RTL8153 chip can drop DCP multicast frames under load. Always use the built-in PCIe Ethernet port for the PG/PC interface in PROFINET commissioning. If the laptop has only USB-C ports, use a Thunderbolt 3 docking station with a wired Intel I210 / I211 Ethernet chip.

Switch port configuration

Managed PROFINET switches from third-party vendors (e.g. Cisco IE-3300, Hirschmann RS20) require PROFINET QoS and LLDP to be enabled. Disable energy-efficient Ethernet (EEE / 802.3az) on every port that is wired to a Siemens station. The PROFINET ASIC on S7-300 will not link up with EEE enabled.

MRES behavior

A memory reset (MRES) on a 315F-2 clears the IP address. If the user pressed MRES on the CPU and then expected Proneta to still find the CPU, this is the reason. Re-assign the IP with PST as described in Solution A.

Procedure Summary Flowchart

Comparison: PST vs Proneta vs SAT

Frequently Asked Questions