S5 to S7-1500 Partial Migration COM Profibus and ET200U Retention

1. Overview

A partial migration from a SIMATIC S5-115U (with ET 200U remote I/O) to a SIMATIC S7-1500 (with ET 200SP) is a classic brownfield retrofit scenario. The challenge is that the existing Profibus DP field devices and the ET 200U/B distributed stations must remain in service while the CPU, program, and engineering platform are swapped within a tight production stop window (often < 4 hours for a single cutover phase).

This reference documents the field-proven procedure for uploading the existing Profibus DP configuration using COM Profibus v5.1, exporting it as a GSD-compatible master configuration, re-creating the ET 200U network under a S7-1500 CM 1542-1 / CM 1542-5 or an IE/PB Link PN IO (6GK1 411-5AB00), and reusing the S5 logic in TIA Portal without re-terminating or re-wiring the field. The end result is a staged migration where the DP slaves remain on the original addresses while the master is swapped in steps.

The information consolidates the procedures published in the Siemens Migration Guide: SIMATIC S5 to SIMATIC S7, the COM Profibus manual, and field experience on staged retrofits.

2. Prerequisites and Licensing

3. Identifying the S5 PROFIBUS Master Type

Before any code is touched, the IM (Interface Module) installed in the S5-115U rack must be identified. The IM dictates how the Profibus network was configured and how it can be reused.

Diagnostic step: Open the S5 rack and read the front-panel MLFB of the IM module. If only a S5-95U is present, the SINEC L2 manual (linked below) describes how the DP parameters live inside DB1. The module type drives the choice of COM Profibus Import versus manual GSD import in TIA Portal.

4. Uploading the PROFIBUS Configuration with COM Profibus

COM Profibus v5.1 is the only tool that natively reads the S5 IM 308C / IM 318C configuration. Procedure:

1. Install COM Profibus v5.1 on a Windows 2000/XP-class machine. The installer is shipped on CD with the original 6ES5895-6SE03 package.
2. Connect a Siemens MPI/Profibus programming cable to the IM 308C and select Online → Upload PG → PROFIBUS Configuration.
3. COM Profibus will read the active DP parameter set from the IM's EEPROM. Save the project as a *.CPF file.
4. Export the configuration as a generic DP master file (CSV / GSD-referenced) using File → Export → DP Master Configuration.
5. Note every DP slave address, GSD revision, I/O byte count, and diagnostic address — these will be re-entered in TIA Portal.

5. Importing the GSD File and Building the ET 200U Slave in TIA Portal

For each ET 200U / ET 200B head module present on the S5 network, install the matching GSD file into TIA Portal:

1. Download the GSD from the Siemens Support pages — for ET 200U see PROFIBUS GSD files: ET 200U (ID 113652); for ET 200B see PROFIBUS GSD files: ET 200B (ID 113304).
2. In TIA Portal, open Devices & Networks → Options → Manage GSD Files and install the GSD.
3. Add the ET 200U station to the DP master system (CM 1542-5 or IE/PB Link PN IO). The slots in the DP slave will mirror the I/O modules actually installed in the field.
4. Match the I/O addresses (byte/bit) to the original S5 PII/PIQ assignment as recorded in the COM Profibus upload.

6. Bridging with IE/PB Link PN IO

When the S7-1500 uses only a PROFINET interface (CPU 1515-2 PN, 1517-2 PN, etc.) and the field remains PROFIBUS-DP, an IE/PB Link PN IO (6GK1 411-5AB00) is the cleanest bridging device. The Link acts as a PROFINET I/O device on the S7-1500 side and as a PROFIBUS-DP master on the field side, forwarding the process image transparently.

6.1 Topology (SVG)

Configuration steps in TIA Portal:

1. Add the IE/PB Link PN IO as a PROFINET IO device on the S7-1500 PROFINET subnet.
2. Assign a PROFINET device name (e.g., iepb-link-01) using Online → Assign PROFINET device name.
3. Open the Link's DP master port and insert the ET 200U stations at the same Profibus addresses used by the original IM 308C.
4. Compile and download the Link configuration. The S7-1500 CPU accesses the ET 200U I/O as if it were a local DP master system.

7. Code Migration Path (S5 → S7-1500)

Siemens provides a toolchain that converts S5 STEP 5 STL source into STEP 7 V5.5 STL/FBD, which is then re-imported into TIA Portal. The procedure follows the Siemens S5 → S7 Migration Guide.

1. Open the S5 project in STEP 5 (DOS/Win). Archive the project to a floppy / file.
2. Open STEP 7 V5.5 SPx. Use File → Migrate Project → S5 Project to convert blocks into S7-compatible STL.
3. Verify the conversion report. Manual rework is required for:
   • Direct I/O access (PY/PW) replaced with PII/PIQ
   • Time-base functions (T 0..T 31 → IEC timers)
   • Counter functions (C 0..C 31 → IEC counters)
   • Special function blocks (FB 240, FB 241, etc. — no S5 → S7 1:1 mapping)
4. Open the S7 V5.5 project in TIA Portal. Use Project → Migrate project → S7 project to TIA Portal V16+.
5. Select a target S7-1500 CPU. The migrator will recreate OBs, FBs, FCs, DBs, and the symbol table.

8. Symbol Table and DB1 Migration

The S5 symbol table (ZIP / SEQ file) carries the field I/O naming. To preserve the I/O names in the new project:

1. In STEP 5, export the symbol table to a SEQ file: File → Symbol → Export.
2. In STEP 7 V5.5, import the SEQ file via Options → Symbol Table → Import. Map the absolute addresses to the S7 PII/PIQ ranges as converted.
3. In TIA Portal, the symbol table is migrated automatically; verify that the I/O symbols resolve to the correct addresses on the IE/PB Link or CM 1542-5.

DB1 (in IM 308B / S5-95U systems) is special: it carries the L2 / Profibus parameters. This DB is not used by the S7-1500. The Profibus parameters are stored inside the TIA Portal hardware configuration of the CM 1542-5 / IE/PB Link. Keep the original DB1 in the S5 archive for reference but do not copy it to the S7-1500.

9. Incremental Slave Activation with D_Act_DP

For staged migration of multiple ET 200U stations, the S7-1500 provides D_Act_DP (FB 733 in the standard library, or via the instruction Distributed I/O — Activate/deactivate DP slave). This instruction activates and deactivates a single DP slave without producing a CPU stop.

9.1 Sample call in SCL (S7-1500)

// Deactivate ET 200U #3 for offline maintenance
IF "Tag_Slave3_Disable" THEN
    "D_Act_DB".REQ   := TRUE;
    "D_Act_DB".MODE  := 0;          // 0 = deactivate
    "D_Act_DB".DP_ID := 204;        // diagnostic address of ET 200U #3
    D_Act_DP(REQ := "D_Act_DB".REQ,
             MODE := "D_Act_DB".MODE,
             LADDR := "D_Act_DB".DP_ID,
             RET_VAL := "D_Act_DB".RET_VAL,
             BUSY := "D_Act_DB".BUSY);
    "D_Act_DB".REQ := FALSE;
END_IF;

IF ("D_Act_DB".RET_VAL <> 0) THEN
    // Log error: see section 11 troubleshooting matrix
END_IF;

There is no equivalent function on the S5 family. On the S5-115U, the only way to "disable" a DP slave is to remove it from DB1, which forces a STOP/RUN. Therefore, the partial migration is one-directional: the S7-1500 controls the activation state of the DP network.

10. Verification and Commissioning

1. DP slave list comparison. After download, open Online → Online & Diagnostics → DP master system → Station list. The list must match the S5 IM 308C configuration 1:1 (addresses, GSD revisions, diagnostics).
2. Process image length check. PII/PIQ length on each ET 200U station must equal the S5 reference. A mismatch typically indicates a wrong slot module type in TIA Portal.
3. Watchdog timing. With the S5 reference at 10 ms, do not reduce the S7-1500 watchdog below this value during the migration phase.
4. OB82 / OB86 behavior. Briefly pull a DP connector; the CPU should log a station failure (OB86) and, after re-connect, an OB82 station return. Confirm the HMI / SCADA shows the diagnostic event.
5. D_Act_DP round-trip. Deactivate and re-activate each ET 200U station in turn. Verify RET_VAL = 0 and that the station returns to data exchange within < 2 s.
6. Time-sync / time-tagging. Verify that the S7-1500 time stamps in the diagnostics buffer match the S5 reference log (drift < 100 ms).

11. Troubleshooting Matrix

12. Field-Proven Cutover Checklist (4-Hour Window)

13. Frequently Asked Questions