Backing Up S7-300/S7-400 PLC Projects in Simatic Manager

Overview

Backing up an S7-300 or S7-400 PLC project from SIMATIC Manager (Step 7 V5.x) is a recurring commissioning and maintenance task. Unlike S7-1200/S7-1500 projects in TIA Portal, classic S7-300/400 stations are not a single self-contained file on the CPU. The CPU stores compiled blocks, system data, and diagnostics buffers, but it does not retain symbolic names, network comments, or the hardware configuration tree as human-readable source. Any backup strategy must therefore be chosen with full awareness of what is — and is not — recoverable from the device.

This reference covers the three practical backup paths engineers use in the field:

1. Station Upload to PG – reverse the online connection to pull every block out of the CPU.
2. Accessible Nodes Browse – recover a CPU whose IP/address is unknown or whose project file is missing.
3. Original Project + Online Sync – the recommended path when an engineered archive exists, using upload as a delta-update tool.

The procedures apply to Step 7 V5.5 / V5.6 + SPx, SIMATIC Manager, and the optional Automation Maintenance Manager (AMM) add-on. Special notes are included for F-CPUs such as the 317F-3 PN/DP referenced in the field report.

Prerequisites

What an S7-300/400 Backup Actually Contains

Before touching the upload button, an engineer must understand the storage split between the PG project and the CPU flash/MMC. The table below summarises what survives a CPU → PG upload and what is lost.

Field-proven consequence: an upload is a last-resort backup, not a primary one. A greenfield backup that starts from the original engineered project is always preferable.

Method 1 – Station Upload to PG (Standard Backup)

Use this when you have online visibility of the CPU and want to mirror its current image into a new SIMATIC Manager project.

1. Open SIMATIC Manager and select File → New Project. Give the project a name that mirrors the plant naming convention (e.g. PLT01_LINE3_S7300_BKP_2024-05-22).
2. From the menu choose PLC → Upload Station to PG….
3. Select the target network interface. For an Ethernet-attached CPU (e.g. 317F-3 PN/DP), pick the TCP/IP interface that is bound to the correct network adapter. For MPI/PROFIBUS, select the appropriate PC Adapter.
4. Step 7 broadcasts on the selected subnet and lists every reachable node (PN CPUs and CP 343-1 Lean/Advanced/PN). Highlight the target CPU and confirm.
5. SIMATIC Manager creates a SIMATIC 300 Station (or 400) containing the S7 program, System Data, and an empty HW Config placeholder. Save and archive the project (File → Archive) to a .zip.

Verification after upload

1. Go Online → Compare Blocks. The dialog should report “Online and Offline identical” for every block. Any difference indicates a partial upload or a block that was not released (CRST / wrong CPU password).
2. Open the Module Information (right-click CPU → PLC → Module Information) and cross-check the firmware version, serial number, and slot configuration against the plant asset list.
3. Trigger PLC → Diagnostic Buffer to confirm the upload itself did not insert spurious stop events.

Method 2 – Upload via Accessible Nodes (Unknown IP / No Online Project)

This is the path required when the CPU's IP address is unknown, when a project archive has been lost, or when an engineer is dispatched to a site with only the laptop and a cable.

1. Open SIMATIC Manager and switch to the Accessible Nodes view (PLC → Accessible Nodes or click the binoculars toolbar icon).
2. Step 7 enumerates every S7 node it can hear on the selected PG/PC interface. For an Ethernet scan this works even if the CPU's IP is on a different subnet, because the discovery uses the DCP (Discovery and Configuration Protocol) broadcast on the local segment.
3. Right-click the discovered CPU and choose Upload to PG/PC…. SIMATIC Manager creates a fresh project containing the station as described in Method 1.
4. If the CPU is listed with “?” for the IP, you can still reach it: double-click the row, read the MAC address, then assign a temporary IP from the Target System → Ethernet Node dialog or by using PLC → Ethernet → Assign IP Address.

Method 3 – Original Project + Online Synchronisation (Recommended)

Whenever a known-good engineered project exists, use it as the seed and let the upload refresh only the deltas. This preserves symbolic names, hardware comments, and the NetPro configuration.

1. Retrieve the original archive (typically a .zip from the engineering server). De-archive it in SIMATIC Manager (File → Retrieve…).
2. Open the project, expand the S7 program, and go Online → Connect to Target System.
3. Run PLC → Compare Blocks (Online/Offline). SIMATIC Manager marks blocks that differ. For each block, choose Update block from online system if the in-CPU version is authoritative, or Download to target system if the PG version is the master copy.
4. For HW Config: open the station, click Online → Hardware Diagnostics, then Station → Upload to PG. This refreshes the slot assignment without overwriting comments and the catalog order you already have on the PG.
5. Save the project and re-archive with a timestamped filename.

Configuring the PG/PC Interface

The Set PG/PC Interface applet is the single most common failure point for S7-300/400 uploads. Configure it before any other step.

1. Open Start → Siemens Automation → Set PG/PC Interface (or run S7EPARDA.exe from the Step 7 install path).
2. Select the access point S7ONLINE (STEP7).
3. Choose the interface that physically connects to the CPU:
   • TCP/IP → your Ethernet adapter (for PN/PN-X/CP 343-1)
   • PC Adapter (MPI) or PC Adapter (PROFIBUS) → for MPI/PROFIBUS
   • Internal – Local → only for S7PLCSIM
4. For Ethernet: assign a static IP to the Windows network adapter in the same subnet as the CPU (e.g. CPU 192.168.0.10 / 24 → PC 192.168.0.20 / 24). Disable any second active adapter on the same machine; Step 7 binds to the first one it finds and often picks the wrong one.
5. For PN CPUs without a configured IP (factory state 0.0.0.0): use the Accessible Nodes → Assign Ethernet Node dialog with the CPU's MAC address (printed on the front label, format 08-00-06-xx-xx-xx).

Resolving “Unable to Reach the Module” Errors

The 317F-3 PN/DP error reproduced in the field report is the canonical symptom of a mismatched PG/PC interface. The following diagnostic ladder resolves it in >95 % of cases.

Special Handling for F-CPUs (e.g. 317F-3 PN/DP)

An F-CPU carries additional constraints that affect backup strategy.

• F-signature: Every safety block carries a signature derived from the F-library version. The signature is stored only in the PG project, not in the CPU. After an upload, Step 7 will report a signature mismatch; accept the F-signature change in Safety → Adjust to bring the project back into a consistent state.
• F-runtime groups: These are compiled and stored in system data. Upload restores them as a blob but cannot decompile the OB 35/OB 123 F-runtime source.
• CPU password: F-CPUs always require a password for read/write. Use PLC → Access Rights → Setup to confirm the password; the upload will fail with “No password or wrong password” if the PG does not know it.
• Know-how protection on FBs: Encrypted F-blocks are stored encrypted in the CPU. The upload returns the encrypted form; the source on the PG remains the only readable copy.

Integrating AMM for Scheduled, Auditable Backups

AMM is the right tool when a maintenance team needs recurring backups of dozens of S7-300/400 stations.

1. Launch SIMATIC Automation Maintenance Manager and create a new maintenance project.
2. Add a station entry for each CPU, specifying its IP / PROFIBUS address, the rack, and slot, and the rack/station template used to interpret the SDBs.
3. Define a backup job: choose Backup type = Complete (full upload), Schedule = Daily 02:00, and a target path on the engineering file share.
4. Enable Versioning so that AMM keeps a history of uploads and a delta log. Each backup produces a *.arc archive and an XML inventory.
5. Optionally enable Compare with reference; AMM will e-mail the operator when an in-CPU image diverges from the engineering reference (e.g. after an unauthorised download).

Archiving and Long-Term Storage

SIMATIC Manager's File → Archive uses a PkZip-compatible container. Recommended practices:

• Archive both the project tree and a separate export of the symbol table (Options → Symbol Table → Export) so a corrupted archive can still be hand-rebuilt.
• Store archives in a versioned directory \fileserv\projects\S7300\<line>\<YYYY-MM-DD>\.
• Capture the upload log (e.g. the online.log written by AMM) and attach it to the archive – it provides the audit trail that the file matches the running CPU at a specific timestamp.
• Re-test restoration at least once a year: extract the archive on a clean VM, install Step 7, de-archive, and confirm the project opens and that Compare Blocks (Online/Offline) matches a known-good CPU.

Troubleshooting Matrix

FAQ