Configuring OP277 6" PROFIBUS I/O on S5-115 After OP25

1. Migration Overview

The Siemens OP25 (Coros OP25 / ProTool era, 5.7" STN) and OP277 6" (WinCC flexible 2005 era, 5.7" STN) belong to different generations of SIMATIC HMI panels. The OP277 is the modern, long-life-cycle replacement that is fully supported by WinCC flexible 2005/2007/2008 and the TIA Portal HMI configuration. When replacing an OP25 against an S5-115 (or S5-135/S5-155) controller over PROFIBUS-DP, the most common engineering issue is not the WinCC flexible project conversion — that step is largely automated — but the PROFIBUS I/O slot configuration that defines the panel's input and output address ranges on the S5 side.

The OP25 originally consumed 32 words of outputs (QW) and 32 words of inputs (IW) on the S5, mapped to data word range DW 220–252 (one combined range for both directions). The OP277 6" PROFIBUS variant, however, is published in its GSD file with a non-symmetric data footprint: 32 words of outputs and 64 words of inputs when the panel is configured with PROFIBUS DP class "middle" (also referenced as class B in some Siemens documentation). This asymmetry is the root cause of the Q/I address alignment problem described in the field issue.

2. Prerequisites

1. Engineering software: WinCC flexible 2005 SP1 (or later — SP3 / 2007 / 2008) for HMI configuration; ComProfibus V5.x or Step 7 COM PROFIBUS for the DP master configuration; ProTool/Pro V6.x or WinCC flexible 2005 to open the migrated OP25 *.pdb project for the OP277 conversion wizard.
2. Original project: OP25 backup (ProTool project file), S5-115 STEP 5 program backup, and the original ComProfibus DP master configuration for the OP25 slot.
3. GSD file: Siemens GSD for the OP277 6" — the file SIEM8111.GSD (or a later variant such as SIEM8112.GSD) describes the available I/O length tuples per DP class. The GSD is shipped with WinCC flexible 2005 or downloaded from the Siemens Product Support portal.
4. Hardware: S5-115 with PROFIBUS-DP master interface (e.g., CP5431 FMS/DP or IM 308-C; the IM 308-C was the standard DP master for S5-115). PROFIBUS cable with terminated bus connectors; 24 V DC supply for the OP277.
5. Firmware: OP277 6" must run the WinCC flexible 2005-compatible image. Verify firmware via the panel's Service & Commissioning menu (Start Center → Settings → System → Device Status).

3. S5-115 and OP25/OP277 PROFIBUS Data Footprint

The 64-word asymmetry of the "middle" class is a key reason the OP25 → OP277 conversion is non-trivial. The S5-115 expects the panel's output image and input image to start on the same data-word boundary, because the IM 308-C or CP 5431 DP only accepts symmetric I/O slot configurations in standard operation.

4. Root Cause of the Address Misalignment

The OP25 occupied 32 QW + 32 IW contiguous, beginning at DW 220, ending at DW 252 — a 64-word window aligned to 32-word boundaries.

With the OP277 in class "middle", the slot requires 32 QW + 64 IW. To satisfy the IM 308-C requirement that Q and I start at the same address, the engineer is forced to align IW to the longest length:

• Start address DW 188 (lowest aligned start given 64-word IW):
• IW window: DW 188–251 (64 words)
• QW window: DW 188–219 (32 words)

The desired OP25-compatible output range was DW 220–251 (32 words). The QW window must be moved to DW 220, but that violates the equal-start-address rule. Net effect: the panel's outputs collide with the upper half of the input window in S5, and the S5 program cannot separate them without restructuring DB/PA areas.

5. Solution — Switch to PROFIBUS DP Class "tiny"

The OP277 6" GSD defines a second configuration, class "tiny", that uses 32 QW + 32 IW. With this class selected in ComProfibus, the I/O footprint is identical to the OP25, and the panel can be plugged into DW 220–251 (or DW 220–252 depending on word/byte boundary convention used by the S5 project).

5.1 When "tiny" is the right choice

• The S5 STEP 5 program only uses the HMI area for status bits and acks, and the HMI tag count fits within 32 IW + 32 QW.
• The OP25 application had no area-pointer (AKZ) or large-mailbox structures that consumed more than 32 IW.
• There is no plan to expand the tag database of the OP277 beyond 32 input words.

5.2 When "middle" is mandatory

• The WinCC flexible project contains more than 32 input words of HMI tags (e.g., 200+ process values).
• A recipe function or trend viewer in the OP277 requires bulk data transfer through the input area.
• You intend to use the optional PROFIBUS diagnostic slot of the OP277 (only available in class "middle").

6. Step-by-Step Configuration in ComProfibus

1. Import the OP277 GSD in ComProfibus (Options → GSD files → Install). Select SIEM8111.GSD. Verify the OP277 6" appears in the device catalog under "HMI / OP".
2. Open the master configuration previously used for the OP25 (DP master is the IM 308-C slot in the S5-115 rack).
3. Replace the OP25 slot with the OP277 entry from the catalog. Drag the OP277 to the same PROFIBUS address that the OP25 had.
4. Open the slot configuration dialog (right-click → Properties or double-click). The GSD offers the choice between configuration "tiny" and "middle".
5. Select "tiny" for the 32/32 layout. Click the configuration row labeled "Configuration slot 0 — 32 words out / 32 words in".
6. Set the DP slot's starting address on the S5 side. To preserve the OP25 mapping, enter 220 as the QW start and 220 as the IW start (ComProfibus uses the convention "Output address" and "Input address" separately; both must be set to 220).
   Equivalently, in hex: QW start 0xDC, IW start 0xDC.
7. Save the ComProfibus database and export the resulting *.LDB (loadable database) for the IM 308-C firmware.
8. Transfer the new LDB to the IM 308-C using PGLoad or STEP 5 add-on, in place of the OP25-era LDB.

7. WinCC flexible 2005 / 2008 Configuration

1. Open the OP25 ProTool project in WinCC flexible and run the conversion wizard to produce an OP277 6" project.
2. Open the connection in the project tree: Connections → HMI_OP277 → S5-DP (or S5-AS511 direct). Confirm the panel is set to "PROFIBUS DP" connection type with baud rate matching the master (default 1.5 Mbps for S5-115 IM 308-C).
3. Open Area Pointers (Connections → Area Pointer). The three most relevant pointers:

4. Verify that the QW area pointer fits in 32 words. If the OP25 mailbox occupied DW 220–251, keep DB 1 starting at DW 220 and length = 32. If the area pointer for PLC→HMI defaults to 64 words, the WinCC flexible project must be edited to set the length to 32 to match the "tiny" class.
5. Compile the project and perform a consistency check (Project → Compiler → Consistency check). The compiler will warn if the area pointer length and the GSD configuration do not agree.
6. Download the OP277 runtime to the panel via RS-232 / Ethernet / USB-PPI (panel-specific cable, 6XV1 440 series) or PROFIBUS programming router.

8. Address Calculation Formulas

For a symmetric 32/32 layout starting at base address A (decimal word offset in S5 data word space):

• QW range: [A, A+31]
• IW range: [A, A+31]
• Combined DW range: [A, A+31] (input and output share the same range by PROFIBUS convention but are differentiated by direction, not address)

For the "middle" class 32/64 layout:

• QW range: [A, A+31]
• IW range: [A, A+63]
• The S5 STEP 5 program must reserve the [A+32, A+63] words exclusively for PLC→HMI, because the OP277 input slot in class "middle" extends that far.

Boundary checks (in bytes, useful for IM 308-C parameterizing):

• 32 words = 64 bytes
• 64 words = 128 bytes
• 96 words (middle total) = 192 bytes

For the OP25-era example with A = 220:

• QW: DW 220–251
• IW (tiny): DW 220–251
• IW (middle): DW 220–283 — 32 words beyond the original OP25 range

9. STEP 5 Program Considerations

The STEP 5 program for the S5-115 should follow these rules:

1. Avoid S5 system data words in the chosen range. DW 0–255 in CPU 115 are partially reserved for system data. Confirm the CPU's reference manual; typically DW 0–127 and DW 200–255 are user-safe. If the desired start is DW 220, the user area is DW 220–252 — leave DW 253–255 for S5 internals.
2. Define a DB for HMI data. e.g., DB 100 with:

DB 100
  DW 0  'HMI control word (Q from panel, mapped from area pointer)
  DW 1  'HMI status word
  ...
  DW 32 'Last QW slot (e.g., recipe ack)
  DW 33 'First IW slot (e.g., process values from PLC to panel)
  ...
  DW 64 'Last IW slot (middle) / DW 32 (tiny)

3. Update the area pointer DBs in WinCC flexible to match DB 100, DW 0 and DB 100, DW 33 (or 1 for tiny).
4. Bit-granular access on the S5 side uses commands A DB 100 + A D 0.0 for bits, or L DW 0 for word-level. Area pointer integrity is not enforced by the S5 runtime — the application is responsible.

10. Verification Procedure

1. Power on the S5-115 with the new IM 308-C LDB, then the OP277 6". The OP277 boot screen should appear within 30 s.
2. Watch the OP277 status bar. With class "tiny" correctly selected, the connection icon (lower-right) should display a green PROFIBUS LED with no red diagnostic flags.
3. Open the panel's Service & Commissioning → Diagnosis and verify PROFIBUS address, baud rate, I/O length (must show 32/32).
4. Toggle a single bit in DB 100 DW 0 from a STEP 5 debug or by forcing it via PG. Confirm the change is visible in WinCC flexible online watch on the linked tag.
5. Toggle a tag in the HMI (e.g., a button with a Set Bit action) and verify the corresponding S5 bit changes state (cross-check via PG online watch on the S5).
6. Run a stress test by cycling 32 input words through a script or by using WinCC flexible's tag simulator. The S5 application should not see any timeouts or duplicate data.

11. Troubleshooting Matrix

12. Migration Checklist

• [ ] Convert the OP25 ProTool project to OP277 6" via the WinCC flexible conversion wizard.
• [ ] Count the migrated HMI tags; confirm ≤ 32 input words are used (or plan to extend the S5 area for "middle").
• [ ] Install the OP277 6" GSD in ComProfibus.
• [ ] Reconfigure the IM 308-C slot: class "tiny" (recommended) or "middle".
• [ ] Adjust the WinCC flexible area pointer lengths to match the chosen class.
• [ ] Adapt the STEP 5 DB definitions to the chosen Q/I split.
• [ ] Compile WinCC flexible, download to the panel.

13. Related Siemens Documentation

For deeper reference, consult the Siemens Product Support entries that document the OP277 GSD and S5-DP integration:

• Entry 29027316 — OP277 / OP270 PROFIBUS GSD notes and configuration examples
• FAQ 21688871 — Frequently asked questions on OP77/OP277 and S5-115 communication
• WinCC flexible 2005 Communication Manual, Part 1
• SIMATIC S5-115 Programmable Controller, manual (6ES5 998-0SH22)