S7-314C-2 DP CPU Program Upload: Cable, Software, and Firmware

1. Overview: Recovering Programs from the S7-314C-2 DP (6ES7 314-6CF02-0AB0)

The SIMATIC S7-300 CPU 314C-2 DP, order number 6ES7 314-6CF02-0AB0, ships with firmware V2.0 and predates the TIA Portal generation of engineering tools. The hardware remains serviceable in 2024 and 2025, but the software path is the bottleneck. A user attempting to upload the project with STEP 7 Micro/WIN (S7-200 only), STEP 7 Lite, or a USB/PPI Master Cable will fail to make any logical connection. The correct path is STEP 7 V5.5 (SP2 or later) or V5.6 plus a USB PC Adapter or CP 5711 with MPI/DP protocol. TIA Portal access is reached only after a firmware update to V3.3 (or by swapping the CPU for a 6ES7 314-6CH04-0AB0).

This article walks through hardware identification, cable selection, software selection, the connection procedure, an optional firmware update to make the CPU TIA Portal friendly, the practical question of MMC migration between the -0CF02 hardware and its successor, verification, and a troubleshooting matrix.

2. Hardware Identification and Order Number Decoding

Decode the MLFB (Machine-Readable Product Designation) before selecting a toolchain. The 6ES7 314-6CF02-0AB0 string breaks down as follows:

Key derived facts for the 6ES7 314-6CF02-0AB0:

• Work memory: 64 KB program / 64 KB data; load memory via MMC.
• Integrated I/O: 24 DI (24 V DC), 16 DO (0.5 A), 4 AI (0-10 V / 0-20 mA / Pt100), 2 AO (0-10 V / 0-20 mA).
• Integrated technology: 4 high-speed counters up to 60 kHz, 1 SSI encoder interface, frequency measurement, pulse-width modulation.
• Two DB9 ports: Port 1 (X1) MPI/DP master, Port 2 (X2) DP slave/master.
• Micro Memory Card (MMC) slot, 8 MB maximum.
• Firmware release at delivery: V2.0; can be upgraded to V3.3 via the OS update procedure.
• Bit timing: 1 ms OB1 minimum (process image update default 1 ms; can be tightened to 0.5 ms).

3. Software Toolchain Compatibility Matrix

Selecting the wrong engineering tool is the most common cause of a failed upload. Use the table below as a single source of truth. The version numbers reflect the catalogs and EDD files bundled with the installer.

4. Communication Cable and Adapter Selection

The single biggest practical trap is using the wrong cable. The S7-200 USB/PPI Master Cable 6ES7 901-3DB30-0XA0 speaks only PPI, an S7-200 protocol. The S7-300/400 CPU 314C-2 DP expects MPI or DP on its Port 1. TIA Portal V11/V12 has no MPI Online Access node, which is why the COM port appears in PG/PC settings but the TIA Online tree shows nothing.

Recommended for a modern service laptop: 6ES7 972-0BA12-0XA0 (A2) or 6GK1571-1AA00 (CP 5711). The CP 5711 is more robust on USB 3.0 hubs and over long MPI bus runs; the A2 is cheaper and well proven for non-industrial service benches. Both are recognized by STEP 7 V5.5/V5.6 and the older Set PG/PC interface applet.

4.1 Cable Selection Flowchart

5. STEP 7 V5.5 Connection Procedure

The procedure assumes a Windows 10/11 PC, STEP 7 V5.5 SPx or V5.6, and a USB PC Adapter A2 or CP 5711. Administrative rights are required for the COM port and driver installation.

1. Install STEP 7 V5.5 from the official Siemens DVD or the licensed download. Apply the latest Service Pack (K5.5.x for V5.5; K5.6.x for V5.6). Confirm the install via Help → About in SIMATIC Manager.
2. Install the PC Adapter driver. On Windows 10/11, right-click the installer in compatibility mode Windows 7 if the auto-launch fails. Reboot before plugging the adapter.
3. Plug the USB PC Adapter. Windows enumerates it as a virtual COM port; the exact COM number appears in Device Manager under Ports (COM & LPT) → SIMATIC PC Adapter USB A2 (COMx).
4. Open Set PG/PC Interface (Control Panel applet). Select PC Adapter (MPI/DP) > PC Adapter (MPI). Click Properties.
5. Configure the MPI tab:
   • Transmission rate: 187.5 kbps (default, safe for any S7-300/400).
   • Highest station address: 31.
   • Time-out: 30 s for the first connection.
   • PG/PC is the only master on bus: leave unchecked if any other DP master is online.
6. Connect the adapter to the CPU's MPI/DP port (Port 1, left DB9 on the front). Hand-tighten the connector screws; a loose connector is the most common cause of intermittent connect/disconnect.
7. Open SIMATIC Manager. In Options → Set PG/PC Interface, verify the same selection as in step 4.
8. Click PLC → Upload Station to PG. The wizard scans the MPI bus, displays the CPU and its order number, and offers to upload to a new S7 project.
9. Confirm the order number is 6ES7 314-6CF02-0AB0. If the wizard reports a different or unknown order number, abort and verify cabling and MPI address. The default MPI address of a brand-new CPU is 2.
10. After upload, open PLC → Module Information to read the firmware version. The Module tab reports the firmware; cross-check against the catalog to decide if a firmware update is needed.

5.1 PG/PC Interface Parameter Reference

The Set PG/PC Interface window for the PC Adapter (MPI) is controlled by a small set of values. The values for a typical first-time connect to a CPU 314C-2 DP are:

PC Adapter (MPI)
  Local connection: COM3 (USB A2, virtual)
  Transmission rate: 187.5 kbps
  Highest station address (HSA): 31
  Timeout: 30 s
  PG/PC only master: unchecked (default)
MPI network:
  My address: 0 (PG is typically address 0)
  Highest station address: 31

6. TIA Portal Connection Limitations and Workarounds

Although the source CPU is visible from STEP 7 V5.5, it does not appear in the TIA Portal V11-V16 hardware catalog as a configurated device. The root cause is that TIA Portal's catalog for S7-300 lists only 6ES7 314-6CH04-0AB0 (FW V3.3) and later part numbers. Two workarounds are possible:

1. Migrate the STEP 7 V5 project into TIA Portal. From TIA V14 SP1 onwards, the menu Project → Migrate a STEP 7 V5 project brings the program into a TIA project. The target CPU is the closest supported one (6ES7 314-6CH04-0AB0, FW V3.3); the migration produces a compatible project you can compile for the newer hardware.
2. Keep the project in STEP 7 V5.5/5.6. This is the safe and conservative path. New development of code is straightforward; document and version the project on the V5 side. TIA Portal is only required if the user has standardized on TIA for new lines.

The "Online Access" view in TIA Portal lists COM/USB, Ethernet (PROFINET) and TCP/IP routes. There is no native MPI node in TIA Portal's online tree for V11/V12. The 6GK1571-1AA00 CP 5711 shows as a virtual COM port and is recognized in PG/PC interface, but only STEP 7 V5 sees it as a live MPI partner; TIA Portal needs the Ethernet side (CP 343-1 Lean or full) for online access on S7-300.

7. Firmware Update via Memory Card (OS Update)

The Siemens Support entry ID 12019198 — Operating System Updates for CPU 314C-2 DP documents the procedure and the supported firmware targets. The 6ES7 314-6CF02-0AB0 can be updated to firmware V3.3 using the OS update card method. The procedure takes 1-3 minutes, requires a STOP selector switch position, and must not be interrupted.

1. Download the firmware update file S7300_CPU314C2_V33.zip from the Siemens Support portal under article ID 12019198. Unzip; the file inside is named FWUPDATE.S7S.
2. Copy FWUPDATE.S7S to a freshly formatted MMC (no other files on the card). A 2 MB MMC (6ES7 953-8LL00-0AA0) or larger is required.
3. Verify the CPU is in STOP. The selector switch on the CPU front must be in the STOP position; MRES is not used for an OS update.
4. Insert the MMC into the CPU and power cycle the S7-300 rack (PS OFF, PS ON).
5. During startup, the CPU reads the file and runs the update. The SF, BF, and DC5V LEDs cycle; the update takes 1-3 minutes depending on the source version.
6. When the SF LED goes out and the STOP LED remains solid, the update is complete. The CPU may restart automatically and run in STOP.
7. Remove the update card, connect STEP 7, and confirm the new firmware in Module Information. The value on the Module tab must show V3.3.

7.1 Firmware Update State Machine

The updated CPU with firmware V3.3 is still functionally the same hardware (still identified as 6ES7 314-6CF02-0AB0), but it is now accepted by TIA Portal V13 SP1 and later. New features enabled by V3.3: support for the integrated web server on a CP 343-1, enhanced diagnostic buffer, optimized block handling, and S7-Communication PUT/GET over the integrated interface.

8. Memory Card Migration Strategy

The question "can I take the MMC out of the old CPU, put it in a new -0CH04, and continue working" has a precise answer from the Siemens compatibility matrix:

• The MMC is electrically and logically the same for both 6ES7 314-6CF02-0AB0 and 6ES7 314-6CH04-0AB0. The card is just a serial flash, not a security element.
• The program stored on the MMC is in the same S7-300 binary format across both CPUs. A program created in STEP 7 V5.5 and downloaded to the MMC will run on either CPU as long as the firmware is compatible.
• The reverse path — a TIA Portal project downloaded to the MMC — requires the new CPU with firmware V3.0+. The old -0CF02 with firmware V2.0 will refuse the block set (download to PG error: "Firmware does not support this block type" or "Invalid block on memory card").
• Migrating the program in one direction: old → new works. New → old does not, unless the project was originally a STEP 7 V5.5 project that is then downloaded via the new CPU to the MMC.

8.1 MMC Compatibility Table for S7-300

Recommended procedure for a service swap from -0CF02 to -0CH04:

1. Upload the program from the old CPU with STEP 7 V5.5 (Save As a new S7 project). Confirm the order number read back from HW Config matches 6ES7 314-6CF02-0AB0.
2. Archive the original MMC with the user's project as a backup. Copy the contents to a labeled folder on the laptop.
3. Install the new CPU (6ES7 314-6CH04-0AB0, FW V3.3) on the rack. Power up; the CPU starts with no project.
4. Insert the old MMC into the new CPU. The CPU will boot from the card and continue in RUN if the program on the card is consistent with the hardware configuration stored on the card.
5. If the HW Config on the MMC references the -0CF02 module instead of the -0CH04, the CPU will report a "Module does not match" diagnostic. Re-upload with STEP 7 V5.5, edit HW Config to the new order number, re-download.
6. Alternatively, use TIA Portal V14+ to migrate the V5 project and download directly to the new CPU.

8.2 SCL Sample for the Integrated Counter

After a successful upload, programs that used the integrated technology of the CPU 314C-2 DP must be re-validated. The block is typically a system function call into the integrated counter. The following SCL example shows how to start, read, and acknowledge counter 0:

// Function FC 100: read integrated counter 0 of CPU 314C-2 DP
FUNCTION FC 100 : INT
VAR
    CountValue : DWORD;
    Status     : WORD;
END_VAR
BEGIN
    // SFB 47 "COUNT" is the integrated counter; instance DB is DB 100
    SFB47.DB100(CU  := I 0.0,   // up-count input
                CD  := I 0.1,   // down-count input
                R   := I 0.2,   // reset
                L   := FALSE,
                PV  := 1000,
                Q   := Q 0.0,
                CV  := CountValue);
    // SFC 51 RDSYSST to read the status of the integrated counter
    Status := SFC51(SZL_ID := W#16#0132,   // diagnostic buffer of integrated I/O
                    INDEX  := 0,
                    SZL    := NIL,
                    RET_VAL := MW 100);
    FC100 := DWORD_TO_INT(CountValue);
END_FUNCTION

9. Verification and Validation

After the upload, run the following checks before signing the project off as recovered:

1. Cross-check the HW Config: Open HW Config in STEP 7; verify each slot matches the physical rack (PS, CPU, IM, SM, FM, CP). The diagnostic buffer will report "Module type mismatch" if the catalog entries disagree with the actual hardware.
2. Block consistency: Run Program → Consistency Check in SIMATIC Manager. Resolve any reference errors (FCs called with wrong parameter count, FBs with mismatched instance DBs).
3. Compare online / offline: With the CPU in STOP, perform PLC → Compare Online / Offline. The result must be "Identical" for a healthy upload.
4. Diagnostic buffer: In Module Information, scan the buffer for "Module inserted/removed" events that occurred during the upload; these are normal.
5. Force table / watch table: If the project uses VAT, verify each VAT's trigger conditions and column setup. Older projects often have VATs that reference symbols which no longer exist after a partial upload.
6. Protection / know-how: The upload returns only the unencrypted blocks. If the original blocks were compiled with S7-Know-How-Protection or S7-Block-Privacy, the uploaded blocks are runnable but the source is not recoverable.
7. Time-stamp / OB1 cycle time: Check Module Information → Performance Data; the OB1 minimum cycle time should be at least 1 ms and the longest cycle under 50 ms for normal operation.

10. Troubleshooting Matrix

11. Field-Proven Notes and Service Bench Setup

• Always carry at least one 2 MB MMC (6ES7 953-8LL00-0AA0) and one PC Adapter A2 to a service call. Together they cover 95% of S7-300 upload and firmware issues.
• If the original programmer used S7-GRAPH, S7-CFC, or S7-SCL add-on packages, install the same packages on the service laptop before opening the project. The blocks compile against the installed libraries; a missing package produces "Library not found" errors at compile time.
• STEP 7 V5.5 / V5.6 runs on Windows 7 SP1 (32-bit best) and Windows 10 LTSC 2019. Windows 11 support is unofficial but works with care. Avoid "home" editions; use Windows 10 Professional or Enterprise.
• For repeated access to many CPUs, build a permanent MPI cable with a 24 V isolated repeater (6ES7 972-0AA01-0XA0) at the bus end. It protects the laptop and improves noise immunity in MCC environments.
• Document the order number, firmware version, MPI address, project name, and last archive date on a label inside the cabinet door. The next service call becomes a one-hour job, not a one-day job.
• Use the STEP 7 V5.5 SP2 K5.5.5.0 or later. The K5.5.5.0 cumulative update is the most current, fixes several USB driver issues on Windows 10 21H2+, and is free of charge for license holders.
• For a license, the floating 50-hour license (order number 6ES7 810-5CC04-0YE5) is the most economical option for service work; the unlimited floating license (6ES7 810-5CC04-0YE2) is required for any engineering office that runs STEP 7 daily. A 14-day trial is available from the official Siemens SIMATIC catalog page.
• For the integrated web server (firmware V3.3 with a CP 343-1) make sure to enable "Enable web server" in HW Config and set a secure password; the default page is reachable on port 80 from any node on the same subnet.