Siemens OP37 HMI Data Archiving Limits and MP377 Migration

1. OP37 Platform Overview

The SIMATIC OP37 (and the related OP27) is a text/graphic operator panel from the Siemens ProTool generation, predating the SIMATIC WinCC flexible and TIA Portal HMI lines. The OP37 family was designed as a low-cost operator interface for SIMATIC S7-200, S7-300, and S7-400 controllers over MPI/PROFIBUS, and it is programmed exclusively with Siemens ProTool / ProTool Pro. It does not run WinCC flexible, WinCC, or TIA Portal projects natively.

Engineering teams encountering an OP37 in a brownfield machine must understand three platform constraints before planning a data archiving strategy:

1. No Ethernet interface is present on the base OP37 hardware.
2. No integrated logging/archiving subsystem is implemented in the ProTool firmware.
3. The onboard floppy drive is a service/recovery interface, not a user data store.

These constraints are documented in the Siemens Industry Online Support entry OP27, OP37 Operator Panels, chapter 9, which covers communication, memory model, and supported functions. Engineers evaluating the OP37 should consult that chapter directly when designing any historian or data-export function.

2. OP37 Hardware Variants and MLFB Identification

Two principal variants exist on the field: the standard OP37 and the higher-feature OP37/PRO. The /PRO suffix indicates additional function keys, expanded message buffer, and an extended recipe/memory model, but the two share the same backplane, the same MPI/PROFIBUS interface, and the same absence of Ethernet.

Before any migration or feature work, capture the full MLFB (Siemens order number) from the rating plate on the rear of the panel. The MLFB determines which ProTool version is required to open the project and whether a migration to WinCC flexible 2008 is viable.

3. ProTool Version Selection by MLFB

ProTool/Pro is the only environment that opens an OP37 source file. Compatibility with the OP37 is not uniform across the ProTool release line; field experience and the Siemens migration manual identify two practical operating points:

• ProTool V4.01 — the earliest release that supports the original OP37. Required for some early MLFBs and for projects that still use ProTool-only objects.
• ProTool V6.0 / SP3 — the last ProTool release and the recommended baseline for late OP37 / OP37/PRO units. Newer SP levels add bug fixes for MPI/PROFIBUS and for the OP37 / OP37/PRO function-key mapping.

Procedure to confirm the correct ProTool version:

1. Read the rating plate and record the full MLFB (for example, 6AV3 637-1LL00-0AX0 or similar).
2. Open the Siemens Industry Online Support entry list and filter by the exact MLFB.
3. Cross-reference the listed ProTool version against the firmware image stored on the OP37 (System Menu → Version).
4. Use the highest ProTool release that supports the MLFB; do not install ProTool 6.0 over a 4.01-only project without re-saving it first.

4. Data Archiving Limitations on OP37

The OP37 firmware does not implement a tag archive. It supports process values, messages, and recipes in volatile runtime memory, but it does not write these to a persistent archive on a network share, FTP server, or SQL backend. The limitations are hard limits in the runtime; they cannot be unlocked by configuration, scripting, or add-on packages because:

• There is no Ethernet MAC, no TCP/IP stack, and no file system suitable for archive handling.
• ProTool for OP37 does not provide a "Logging" or "Archive" editor comparable to WinCC flexible 2008 or TIA Portal.
• VBScript, the scripting language introduced in WinCC flexible, is not available in ProTool for OP37.

Consequences for the data historian:

1. Process values must be logged upstream in the PLC (e.g., DataLog blocks in S7-300/S7-400 or a SIMATIC IPC with WinCC).
2. Long-term trending on the HMI is limited to the operator-viewable curve object, which is RAM-resident and lost on power cycle.
3. Any archiving requirement that depends on the HMI being the data source must be re-platformed to MP377, Comfort Panel, or a SCADA before commissioning.

5. The OP37 Floppy Disk Drive — What It Actually Does

The OP37 ships with a 3.5" floppy drive behind a front-panel door. A common misreading of the hardware is that the floppy can be used to store process archives. It cannot. The floppy drive on the OP37 is reserved for:

• Restoring the Windows CE / ProTool runtime image from a service floppy.
• Performing a clean firmware re-flash when the internal image is corrupted.
• Loading factory recovery sets during commissioning or repair.

Archive writes are blocked at the firmware level. Attempting to write user data to the floppy will fail or corrupt the runtime image. If a removable medium is required for export, the panel must be replaced — there is no firmware patch that enables user-mode floppy access on the OP37.

6. Network Communication on the OP37

The OP37 communicates with the controller through its MPI/PROFIBUS interface only. It does not include a TCP/IP stack, an FTP client, an HTTP server, an OPC server, or an SMTP client. ProTool exposes standard SIMATIC protocols (MPI, PROFIBUS-DP, PPI on a subset of builds), but no IP-based service is available on the panel itself.

For a network-attached historian, the only valid OP37-era path is to push the data from the PLC to a PC-based logger (e.g., a SIMATIC WinCC single-user station, a SCADA node, or a custom OPC client). The OP37 cannot participate as a data source for that path.

7. Migration Path: OP37 → MP377

The SIMATIC MP377 is the designated successor to the OP37. The MP377 family runs WinCC flexible 2008 (or later, via TIA Portal migration) and includes:

• PROFINET (Ethernet) interface for controller and network traffic.
• Integrated tag and alarm logging to internal Flash, SD card, or network share.
• VBScript for application logic and archive triggers.
• OPC DA server for SCADA integration.
• Recipe, audit trail, and user administration objects.

Migration is not a 1:1 conversion. Use the Siemens SIMATIC HMI WinCC flexible 2008 Migration manual as the authoritative reference; it documents which ProTool objects convert cleanly, which require manual rework, and which are simply not available on the target platform. Treat the migration as a project, not a file format operation.

8. ProTool → WinCC flexible 2008 Conversion Procedure

1. Inventory the project — list screens, tags, messages, recipes, area pointers, schedules, and any ProTool-only objects (e.g., trend curves with a fixed sample count, ProTool-Pro status displays).
2. Compile the project in ProTool at the highest supported ProTool release. Resolve all warnings. An unclean compile propagates to the converted project.
3. Install WinCC flexible 2008 SPx on the engineering station. The exact SP is dictated by the target MP377 firmware; consult the Siemens compatibility tool for the panel-image ↔ flexible-version matrix.
4. Run the Migration Wizard in WinCC flexible 2008 (File → Migration). The wizard consumes the ProTool .pdb/.hmi source and emits a WinCC flexible project. Cross-reference each converted object against the migration manual's table of supported objects.
5. Resolve non-converting objects — typically: ProTool status/control objects with custom bitmaps, ProTool-Pro language switching, area pointer schemes that depend on ProTool-only flags, and any ProTool "function" calls that lack a WinCC flexible equivalent.
6. Re-tag with WinCC flexible addressing — the tag DB must be expanded where WinCC flexible expects a wider or differently typed connection (e.g., area pointers for date/time, user login, recipe).
7. Re-implement logging in WinCC flexible. Add a Tag Logging editor instance, define the archive segments, and configure the storage path (internal Flash, SD card, or network path). This step has no equivalent in the original ProTool project.
8. Compile, simulate, and transfer to the MP377. Use WinCC flexible's runtime simulator to verify the screens, the logging triggers, and the script behavior before any plant-power transfer.

9. MP377 Selection for an OP37 Replacement

When the OP37 must be replaced, size the MP377 to match the cutout, the resolution, and the operator workflow. Use the Siemens migration tool, or follow these rules of thumb:

Verify the mechanical depth behind the panel — MP377 is deeper than OP37 in most cases — and re-pull the PROFIBUS / PROFINET cable to the new port. The migration from MPI to PROFINET is a separate engineering task and may require the controller's PROFINET port to be enabled and a new device configuration loaded.

10. MP377 Configuration for Networked Archiving

Once the migration is complete, configure the MP377 to send archives to a server or PC:

1. Set a static IP, subnet, and gateway in the MP377 control panel (Control Panel → Network and Dial-Up Connections → PN-IO).
2. In WinCC flexible 2008, open the project's Tag Logging editor and add an archive per data point. Configure a circular log with a defined size, or a segmented log with file switches.
3. Open Schedules and add a trigger that calls a script, e.g., daily at 23:00, to flush and copy the archive to a UNC path such as \\HMI-ARCHIVE\mp377$\plant01.
4. In the script, use FSO.CopyFile (VBScript) to move the closed archive segment to the target. Example skeleton:

   ' Triggered by schedule, after archive segment closes
   Dim srcPath, dstPath, fso
   srcPath = "\Storage Card\Archives\" & CurrentArchiveName
   dstPath = "\\\\HMI-ARCHIVE\\mp377$\\plant01\\" & CurrentArchiveName
   Set fso = CreateObject("Scripting.FileSystemObject")
   If fso.FileExists(srcPath) Then fso.CopyFile srcPath, dstPath, True
   Set fso = Nothing

5. On the server, grant the MP377 user (the WinCC flexible runtime user, typically Administrator or a dedicated hmi_service account) write permission on the target share.
6. Validate the path with a small test script that writes a placeholder file before commissioning the real archive flow.

11. Verification Checklist

Use this matrix to verify a successful OP37 → MP377 migration plus network archiving:

12. Troubleshooting Matrix

13. Field-Proven Caveats

• The OP37 cannot be re-purposed as an OPC bridge. It is a terminal, not a server. Do not attempt to use it as a data concentrator for downstream historians.
• ProTool V6.0 is not the same product as WinCC flexible 2005. They share some screens in the help system but they are not interchangeable; a ProTool .pdb project will not open in WinCC flexible directly, only via the migration wizard.
• If the OP37 image is corrupted, the floppy recovery set is model-specific. Confirm the MLFB and firmware build before ordering a recovery disk set from Siemens.
• The MP377's PROFINET interface uses the same RJ45 pinout as standard Ethernet, but the panel's IP must be on the IO controller's subnet, not just on the office LAN. Coordinate IP allocation with the controls team, not the IT team.
• Do not assume the OP37 has a CE image on the floppy. The floppy is a recovery medium; the image on it is the one Siemens shipped at build time, which may not match the version the project requires.

14. Quick-Reference Decision Tree

1. Is Ethernet or logging required on the panel? → If yes, replace the OP37 with an MP377 (or newer Comfort Panel).
2. Is the project still maintained in ProTool? → If yes, finish development in ProTool, then plan the migration.
3. Is the MLFB supported by WinCC flexible 2008 migration? → Verify in the SIMATIC HMI WinCC flexible 2008 Migration manual.
4. Is the network architecture PROFINET? → The OP37 stays on MPI/PROFIBUS; the MP377 moves to PROFINET. Plan a controller-side PROFINET port and a new device configuration.
5. Is the data path: PLC → MP377 → server? → If yes, configure Tag Logging on the MP377 plus a scheduled VBScript that copies closed segments to a UNC share.