Overview
This procedure rebuilds a SIMATIC S7-300 station that uses the CP 342-5 PROFIBUS communications processor and an integrated CPU 315-2DP after a backup-battery replacement event. The reported symptom set is classic: SF lit red on the CP 342-5, STOP lit amber, and WinCC reporting Cannot connect to API_AMX30 with error codes 0xFFDF_411C / 0x0000_7000. Because the engineering workstation only ships with COM PROFIBUS V3.3 and COML7 V2.12 (no STEP 7, no NCM S7), the workflow must follow the legacy configuration path that preceded HW Config and NetPro.
The goal is to: (1) confirm whether the user program survived in the Flash memory card, (2) re-author the PROFIBUS master/slave database (LDB) using COM PROFIBUS, (3) re-author the S7-300 station hardware using COML7, (4) write the configuration to the 5 V Flash card, (5) bring the CPU to RUN, and (6) re-establish the WinCC V5.1 <-> CP 5613 <-> S7-300 connection.
Hardware Identification and Specifications
Confirm every catalog number before configuring. Mixed-version modules will silently reject a configuration built for a different article number.
| Module | Catalog Number | Role in this Station |
|---|---|---|
| CPU 315-2DP | 6ES7 315-3Fx-0AB0 | Central processor; integrates PROFIBUS DP master on the first IF port |
| CP 342-5 | 342-5DA02-0XE0 (6GK7342-5DA02-0XE0 family) | Additional PROFIBUS DP master/slave communications processor |
| CP 343-2 | 343-2AH00-0XA0 (6GK7343-2AH00-0XA0) | AS-Interface master link to the ASi field network |
| Flash memory card | 6ES7951-0KG00-0AA0 (MC 951 / 128 KB / 5 V) | Non-volatile load memory for project + system data |
| Backup battery | 3.6 V Lithium (per CPU manual) | Retains RAM when 24 V removed |
| PC adapter | CP 5613 (6GK1561-3AA00 / -3AA01) | PCI PROFIBUS/MPI card on the engineering PC |
The Siemens Industry Online Support portal hosts the CP 342-5 manual set (manual order number 6GK7342-5DA02-0XE0 family). For module replacement procedures, refer to CP 342-5 / CP 342-5 FO Equipment Manual (PDF).
Symptom Analysis: Battery-Failure Aftermath
The reported LEDs and WinCC error cluster match a CPU that has lost its user program. The decision tree below identifies the root cause before any re-configuration work begins.
- Backup battery exhausted. The CPU 315-2DP retains RAM (work memory + load memory) from the 3.6 V backup cell. When the cell drops below its end-of-life voltage, RAM data is no longer guaranteed.
- 24 V removed (planned or accidental). Without either a healthy backup cell or a non-volatile image on the Flash card, work memory is cleared and the CPU goes to STOP with no OB1 execution.
- Memory reset performed. MRES wipes RAM and forces a fresh cold start. If the only program copy lived in RAM, it is now gone.
- CP 342-5 has nothing to bind to. Because CP 342-5 (DP) requires FCs/FBs in the user program to allocate connection resources (the DP_SEND/DP_RECV FBs), an empty CPU leaves the CP unable to enter data-exchange. Hence SF (group fault) lit red and STOP amber.
- WinCC connection target missing. The OPC channel cannot open an S7 connection to API_AMX30 because no S7 connection is loaded in the CPU. The error code 0xFFDF_411C / 0x0000_7000 reflects an S7 connection-establishment failure at the application layer.
CP 342-5 LED Diagnostic Reference
Use the LED pattern to differentiate hardware failure from missing program. Compare the table against the observed SF red and STOP amber.
| LED | Color | State | Meaning | Action |
|---|---|---|---|---|
| SF | Red | On | Group fault; configuration error or no communication FB loaded | Check diagnostics buffer; reload program |
| BF | Red | On | Bus fault on PROFIBUS DP segment | Check wiring, terminators, slave addresses |
| RUN | Green | On | CP in cyclic operation | None |
| RUN | Green | Flashing | CP ready, no active data exchange | Check partner configuration |
| STOP | Yellow | On | CP not configured or CPU in STOP | Configure CP; bring CPU to RUN |
| STOP | Yellow | Flashing | CP waits for CPU startup | Confirm CPU is in RUN |
If only BF is lit, the configuration problem is on the PROFIBUS side. If SF + STOP are lit with the CPU also in STOP, the program is almost certainly missing.
Required Software Tools and Compatibility
| Tool | Version | Function | Notes |
|---|---|---|---|
| COM PROFIBUS | V3.3 | Builds the PROFIBUS DP master/slave database (LDB / system data) from GSD files | Predecessor of HW Config / NCM S7 |
| COML7 | V2.12 | Configures the S7-300 station (rack, modules, addresses) and exports to memory card | Predecessor of HW Config for S7-300 only |
| WinCC | V5.1 | HMI/SCADA runtime with OPC channel and S7 driver | Connects via CP 5613 to MPI/DP |
| OPC Server | (bundled with WinCC V5.1) | Exposes WinCC tags via OPC DA | Used for cross-vendor access |
| CP 5613 driver | SIMATIC NET 05/2000, S79220-A5406-F000-01 | PCI PROFIBUS/MPI interface driver | Set PG/PC interface to CP 5613 (PROFIBUS) |
Memory Card Strategy
The 6ES7951-0KG00-0AA0 is a 128 KB 5 V Flash card (MC 951 family). It stores the user program, system data (SDBs), and COML7 / COM PROFIBUS configuration. Two paths are possible.
Path A — Borrow a card from a sister station
- Power down all three sister stations.
- Open the CPU 315-2DP cover, eject the Flash card from a known-good station using the ejector.
- Insert it into the affected CPU.
- Power up and observe the CPU mode selector: leave in STOP until the CPU has read the card.
- Move the selector to RUN; the CPU performs a warm restart from the Flash image.
Path B — Rebuild from scratch with COM PROFIBUS + COML7
Use this path when no sister station is available, or when the project source has been lost.
Step-by-Step: Configure PROFIBUS with COM PROFIBUS V3.3
- Launch COM PROFIBUS. Create a new project; select the master as SIMATIC S7-CP 342-5 DP with article number 6GK7342-5DA02-0XE0.
- Assign master PROFIBUS address. Default is 2; the CPU 315-2DP integrated port typically uses address 2; the CP 342-5 should use a unique address (commonly 3) on the same segment.
-
Import GSD files for every DP slave connected to CP 342-5. From the Device catalog, choose Install GSD and select each vendor's
*.GSD/*.GSEfile. The Siemens legacy sitewww.aut.sea.siemens.comreferenced in the original request is deprecated; use the current Siemens Industry Online Support portal to download GSD files. - Configure slave I/O. Drag each slave onto the bus, set its PROFIBUS address, and select the I/O modules that match the physical hardware (input bytes, output bytes, consistency). Note that CP 342-5 supports a maximum of 16 slots and up to 244 bytes input / 244 bytes output per slave.
- Define the master-slave data exchange. For a CP 342-5 acting as both master (on its segment) and slave (to the CPU 315-2DP integrated port), enable the DP slave mode checkbox and map the data areas. See the Siemens application note Configure CP342-5 as DP Slave to a CP 342-5 as DP Master (PDF).
- Compile and export. Generate the LDB (system data) and save to a directory that COML7 can import.
Step-by-Step: Configure the S7-300 Station with COML7 V2.12
- Start COML7. Choose File > New. Select the S7-300 station profile.
- Build the rack. Place the CPU 315-2DP in slot 2, the CP 342-5 in slot 4 (or any free slot; CP 342-5 occupies 16 digital inputs / 16 digital outputs in the PII/PIQ area), and the CP 343-2 in a free slot. The slot rules follow the S7-300 mechanical layout: power supply (PS) in slot 1, CPU in slot 2, I/O from slot 4 onward.
- Set module parameters. Open each module's properties dialog and enter the PROFIBUS address configured in COM PROFIBUS, the diagnostic interrupt behavior, and the clock-memory byte (if used).
- Import the LDB. From Options > PROFIBUS > Import, point to the file generated by COM PROFIBUS. COML7 merges the DP database into the station's system data blocks (SDB).
- Define MPI/DP routing. The CPU 315-2DP's first interface is the MPI/DP combined port. Enable DP master mode on it if HMI panels or the CP 5613 also communicate through this port.
- Configure S7 connections. Although COML7 predates NetPro, it does support Connection configuration. Create the connection used by WinCC (connection name API_AMX30 from the OPC error report). Specify S7 connection, partner = the CPU's MPI or DP address, and the local end as the CPU 315-2DP itself. Set the access point to S7-ONLINE.
- Compile to memory card image. Use Station > Save to Memory Card. Select drive and confirm. The Flash card is then ready to insert into the CPU.
Programming the Memory Card
- Insert the Flash card into the programming device's external prommer (e.g. PG 740 / Field PG with prommer slot) or, if the CPU supports card programming, place the CPU in STOP with the card inserted and trigger Save to MC from COML7.
- Verify the file size matches the expected system-data size. The MC 951 card with 128 KB should comfortably hold a 300-station program plus the DP database.
- Eject the card, power down the affected CPU, insert the card, and power up.
- Confirm that the CPU performs a warm restart from the card. If the CPU still goes to STOP, read the diagnostic buffer via the CP 5613 MPI cable and an online tool (the legacy S7-DOS or STEP 7 if any version is obtainable).
Bring the CPU to RUN and Verify
- Set the mode selector to STOP, then to RUN. The CPU should run a warm restart.
- Observe the CP 342-5 LEDs. Expected: SF off, BF off, RUN solid green or flashing (flashing = ready but no DP data exchange yet), STOP off.
- From WinCC, open the WinCC Explorer, right-click the S7 Driver connection API_AMX30, and choose Connection Status. The status must read OK.
- If the status remains Disconnected, open the Set PG/PC Interface applet and verify that CP 5613 (PROFIBUS) is the active access point and that the bus profile matches the CPU MPI/DP baud rate (default 187.5 kbps; 1.5 Mbps if the network has been re-profiled).
WinCC V5.1 OPC Channel Setup (Reference)
WinCC V5.1 connects to S7 via the SIMATIC S7 Protocol Suite channel. Confirm:
- The channel unit TCP/IP or PROFIBUS (MPI) is selected — for CP 5613 use PROFIBUS (MPI).
- The connection API_AMX30 points to the CPU's MPI address (default 2) or DP address.
- On the OPC Server side, the same connection name is registered with the matching partner address.
Error-Code Interpretation
The reported error 0xFFDF_411C / 0x0000_7000 originates from the WinCC S7 driver when a connection cannot be established. Although exact bit decoding depends on the driver build, the typical mapping is:
| Code Component | Typical Meaning | Mitigation |
|---|---|---|
| 0xFFDF_ | WinCC driver class prefix (vendor-specific) | Treat as "connection layer error" |
| 411C | Connection establishment rejected (no partner resource) | Confirm connection is loaded in CPU |
| 7000 | Sub-function "no active partner" / job pending | Bring CPU to RUN; verify partner online |
If the codes change after the CPU enters RUN but OPC still fails, capture the diagnostic buffer of the CPU via MPI and look for Communication error entries. The S7-300 diagnostic buffer records any SFB / SFC call failure with its event ID and the connection ID.
Troubleshooting Matrix
| Symptom | Likely Cause | Verification | Action |
|---|---|---|---|
| SF red, STOP amber, CPU in STOP | No user program in CPU | Insert Flash card from sister station | Reload program via COML7 |
| SF red only | DP configuration error | Read diagnostic buffer | Recompile COM PROFIBUS LDB |
| BF red | Cable / slave address / terminator fault | Measure bus voltage, check DIP switches | Repair segment |
| CPU in RUN, OPC still disconnected | Connection not loaded / wrong MPI address | Check NetPro connection in COML7 | Recreate API_AMX30 connection |
| Flash card not accepted | Wrong article number or file format | Verify MC 951 has project files | Reprogram card with COML7 |
| DPdemo download link dead | Legacy Siemens FTP decommissioned | Use current Siemens Support | Download current DPdemo or use PROFINET demo |
Field-Commissioning Notes
- Memory-reset side effect. MRES erases RAM. Confirm that the Flash card contains the project before invoking MRES — otherwise the only copy of the program is lost.
- Battery orientation. Insert the lithium cell with polarity matching the silkscreen on the CPU. Reversed polarity can damage the charging circuit.
- CP 342-5 article matching. CP 342-5 variants (-DA02, -DA03, -DG00) are firmware-incompatible. Replacing one with another variant requires rebuilding the COM PROFIBUS project with the new GSD.
- Legacy software availability. COM PROFIBUS V3.3 and COML7 V2.12 are no longer distributed by Siemens. Local archives on the engineering PC, OEM support, or a Siemens regional representative are the practical sources.
-
Migration path. When modernizing, replace COM PROFIBUS + COML7 with STEP 7 V5.x (HW Config + NetPro) or TIA Portal. The configuration can be rebuilt from the legacy
*.S7Pproject if it can be located.
Verification Checklist
- CPU 315-2DP in RUN, no SF on CPU front.
- CP 342-5: RUN green, BF off, SF off, STOP off.
- CP 343-2: APF off, SF off, RUN on.
- WinCC V5.1 connection API_AMX30 reports Connected.
- OPC Server lists tags of API_AMX30 without quality Bad.
- DP slaves visible on the segment (PROFIBUS monitor tool, e.g. Amprolyzer or BT200).
- Diagnostic buffer of the CPU clean of new communication errors after 1 hour of operation.
Why does the CP 342-5 show SF red and STOP amber after a battery replacement?
The CP 342-5 relies on user-program FBs (DP_SEND / DP_RECV) to bind to DP slaves. After the backup battery was exhausted and a memory reset performed, the CPU lost its user program, leaving the CP unable to enter data-exchange. Reload the project via the Flash card or rebuild it in COML7 + COM PROFIBUS.
Can I configure the CP 342-5 without STEP 7?
Yes, with the legacy toolset COM PROFIBUS V3.3 (for the DP master/slave database) and COML7 V2.12 (for the S7-300 station hardware and S7 connections). Both predate STEP 7 and remain functional on Windows NT / 2000 with SIMATIC NET 05/2000.
Where do I download GSD files for legacy DP slaves today?
The www.aut.sea.siemens.com link referenced in older manuals is decommissioned. Use the current Siemens Industry Online Support portal, search for the slave article number, and open the Downloads tab. For non-Siemens slaves, request the GSD from the slave vendor.
How do I decode error 0xFFDF_411C / 0x0000_7000 from WinCC?
This is a WinCC S7 driver connection-establishment failure. 0x411C indicates the connection resource on the CPU is missing or unreachable; 0x7000 means no partner is currently active. Bring the CPU to RUN with a loaded connection database, and verify the CP 5613 baud rate matches the MPI/DP segment.
Can I borrow the Flash card from one of the three identical sister stations?
Only if all three stations run the same project (same module layout, same DP slave map, same S7 connections including API_AMX30). If they differ, the borrowed card will produce a configuration-error diagnostic on insertion. Verify by comparing CPU article numbers and DP slave addresses before swapping.