OP 277 Function Key Programming in WinCC Flexible Global vs

1. Overview and Scope

The SIMATIC OP 277 6" Key is a membrane-key HMI panel from the SIMATIC 270 series, designed for machine-level operator control with a 5.7-inch (144 mm) STN display, 320 x 240 pixel resolution, and 14 freely assignable function keys (F1–F14) plus a dedicated ESC, ENTER, and cursor block. Although the hardware is mature, the OP 277 remains in service in thousands of packaging, water-treatment, and machine-tool installations. Most field issues are not hardware failures but configuration mismatches introduced by two common situations:

1. Defining a function key globally (i.e., the same F-key triggers the same action regardless of the active screen) versus locally (the F-key triggers a screen-specific action).
2. Migrating an existing OP 270 project authored in ProTool to a WinCC flexible 2004 / 2005 / 2007 / 2008 project on the OP 277.

This reference covers both situations in engineering depth. It documents the template mechanism that gives a function key project-wide scope, the screen-property mechanism that scopes a key to a single screen, the migration of screen numbering, and the post-migration ESC-key behavior that operators often flag as a bug.

2. Prerequisites

3. OP 277 Project Structure Relevant to Function Keys

WinCC flexible stores a project as a tree under the HMI device. The three nodes that control function-key behavior are:

1. Screens → Template — defines elements (including function-key labels and assignments) that are inherited by every screen.
2. Screens → <Screen_001> … — individual screen objects; each has its own Events list for function keys.
3. Project → Function Keys — a cross-screen view that aggregates F1–F14 with their global assignment. The OP 277 has 14 function keys arranged in two columns of seven; the bottom row also includes the system keys (ESC, ENTER, HELP, INFO, ACK on B variants).

Function keys have two independent event sources:

• Global assignment — configured on the template. The configured action runs no matter which screen is currently visible, including the start screen.
• Local assignment — configured on the active screen. The configured action runs only when that specific screen is the foreground image.

If both global and local assignments exist for the same F-key on the same screen, the local assignment takes precedence. The global assignment is suppressed for the duration of that screen. As soon as a different screen becomes active, the local assignment disappears and the global one re-asserts.

4. Programming a Function Key Globally (Independent of Screen Number)

A global F-key is the correct pattern for actions that the operator can invoke from anywhere: Logon, Logout, Language toggle, Stop / Emergency Stop, Acknowledge alarms, Change user, Go to start screen, or Print screen. The configuration is anchored to the template so every screen inherits it.

4.1 Open the template editor

1. In the project tree, expand Screens.
2. Double-click Template (in WinCC flexible 2005+ the node is labelled Template; in some localized builds it is Bildvorlage or Modèle).
3. The template work area opens with the same resolution as the OP 277 (320 x 240).

4.2 Insert a function-key label

1. From the toolbox select Function Keys → drag the appropriate key onto the work area, or right-click in the work area and select Function Key > F1 (or whichever key you require).
2. With the key selected, look at the Properties window on the right. Under General set the Label field to the text shown on the keycap, e.g. LOGIN, HOME, STOP.
3. Optionally assign a graphic to the key via Properties > Picture. A monochrome BMP/ICO is recommended for the OP 277 STN display.

4.3 Wire the global event

1. With the function key still selected, switch to the Events tab in the Properties window.
2. Expand Press. Three sub-events are available:
   • Click — fires on press while the key is held, used for latching logic.
   • Press — single event on the leading edge of the key-press.
   • Release — fires on the trailing edge.
3. Click the … button next to Press. The system functions list opens. Common global functions:

4.4 Compile and verify the global binding

1. Select Project > Compiler > All (or right-click the HMI device → Compile).
2. Open any screen and inspect the template strip at the bottom. The global F-key label must appear on the soft-key strip even though no local assignment exists.
3. Start the runtime simulator (Start > Runtime > Simulator with HMI). Click the F-key from at least three different screens. The action must execute in each.

5. Programming a Function Key Locally (Screen-Specific Only)

A local F-key is the correct pattern when the same physical key on the OP 277 has different meanings on different screens. Typical examples: F5 = Start pump on the Pumping screen, F5 = Open valve 12 on the Valve-Detail screen, F5 = Reset counter on the Diagnostics screen.

5.1 Configure the local event on a specific screen

1. Open the target screen (e.g. Screen_005).
2. Either drag a function key from the toolbox onto the screen or select the inherited key from the template and override its event in this screen.
3. Switch to Events > Press > … and configure the screen-specific function. Examples:
   • SetBit with tag db120.dbx0.0 (S7-200/300) or HMI_Tag_StartPump (internal tag).
   • ActivateScreen "Screen_007" to drill into a sub-screen.
   • SetValue on tag RecipeIndex with value 0.

5.2 Confirm local scope

1. Compile the project.
2. Open the runtime simulator and navigate to Screen_005 → press F5 → observe the expected action.
3. Navigate to Screen_006 → press F5 → observe the global F5 action (if one is configured on the template), or no action at all if F5 is exclusively local.

5.3 Mixed scope — global + local for the same key

This is a common requirement. Configure the global action on the template and the local action on individual screens. Operators will see the local label while the screen is active, and the global label reappears as soon as they navigate to a screen without a local override. To make the operator aware of the local context, the standard approach is to update the function-key label dynamically with a text list or a string tag.

Example using a text list for F5:

1. Create a text list TextList_F5_Labels with three entries: Start pump, Open valve 12, Reset counter.
2. On the template's F5 label element, set Properties > Label > Dynamic and bind to a tag of type INT named CurrentF5Context.
3. In the Loaded event of each screen, set CurrentF5Context to the appropriate index (0, 1, or 2) using SetValue.

6. Screen Number Management and Renumbering

In ProTool the screen number (the integer shown in the title bar and the GetScreenNumber system function) was assigned automatically in the order of creation. After migration to WinCC flexible the numbering can change to 1, 2, 3, 4, …, 18, 19 because the WinCC flexible compiler re-numbers based on its own internal sort. Many PLC programs are coded against the ProTool-era numbers, so reordering breaks the HMI ↔ PLC contract.

6.1 Inspect the current screen number

1. Right-click any screen in the Screens node and select Properties.
2. The General tab shows two fields:
   • Screen name — symbolic, e.g. Screen_017
   • Screen number — the integer, e.g. 17

6.2 Renumber a screen

1. Open the screen's Properties dialog (right-click → Properties).
2. Click the Screen number field and edit it. Valid range: 1 to 32767. Numbers must be unique across the project.
3. Press OK. The screen name is unchanged; only the integer is rewritten.

6.3 Bulk renumber to a clean 1, 2, 3, 4, 5 sequence

1. Sort the Screens node by the order you want them numbered.
2. Open each screen → Properties → Screen number → assign 1, 2, 3, 4, 5, …
3. Update any PLC logic that calls GetScreenNumber in the HMI tag interface so the controller's expected integers match the new numbers.

7. Migrating OP 270 (ProTool) → OP 277 (WinCC flexible)

Siemens officially documented this migration in the manual SIMATIC HMI Configuration Support for Migrators — Migration to Windows-based System. The migration is performed by WinCC flexible's integrated Project Migrator, which reads a ProTool V6.0 SP2 or later archive (file extension .pdb) and writes a new WinCC flexible project (extension .hmi or .hmi_zip).

7.1 Migration steps

1. Open WinCC flexible and create a new project targeting the OP 277 6" Key.
2. From the project menu select Project → Migrate ProTool Project (the wording varies slightly across SPs: in 2005 it is File → Migrate; in 2007/2008 it is under Options → Migrate ProTool Project).
3. Browse to the source .pdb archive, click Open.
4. WinCC flexible generates a migration log (.log). Open it and review Warnings and Errors sections before continuing.
5. Accept the migration. All screens, tags, alarms, and the original function-key assignments are carried over.
6. Compile and run the runtime simulator to validate behaviour.

7.2 What the migrator changes silently

8. ESC Key Behaviour After Migration

The reported symptom — "the ESC key is sometimes not reactive start screen although the key is good" — has three layered causes, ranked by frequency in the field.

8.1 Cause A — global ESC assignment was lost in migration

ProTool configured the ESC key as a project-wide "return to start screen" event. The ProTool → WinCC flexible migrator does not always preserve this binding. The ESC key ends up with no global event and only a per-screen Cancel event on screens where the original ProTool configuration defined one. As a result, on screens that were not explicitly configured in ProTool, the ESC key does nothing.

Fix:

1. Open Screens → Template.
2. From the toolbox, drop a function key onto the ESC position. The OP 277 has a dedicated ESC keycap; in WinCC flexible this maps to the system key ESC.
3. In Properties → Events → Press, select ActivateScreen with the parameter set to your start screen (e.g. Screen_002).
4. Compile. The ESC key will now return to the start screen from every screen.

8.2 Cause B — local ESC assignment overrides the global one

If a screen has its own Press event on the ESC key, the local event suppresses the global one. Common pattern: a confirmation dialog uses ESC as Cancel. After dialog close, the operator presses ESC again, but the local screen has a residual Press binding that swallows it.

Fix:

1. Search the project for any screen that has an ESC → Press event other than the desired start-screen action.
2. Either delete the local event (so the template takes over) or change it to ActivateScreen "StartScreen" explicitly so behaviour is consistent across screens.

8.3 Cause C — key-repeat / debounce on the membrane

The OP 277 6" Key uses a membrane keypad. The debounce is implemented in the OP 277 firmware; the WinCC flexible runtime does not apply any additional filter. If the operator taps ESC very briefly (< 40 ms is the typical minimum pulse width on the OP 277B firmware), the runtime may not register the press.

Fix:

1. Update the OP 277 firmware to the latest available on the Siemens support portal. The most recent version for the OP 277 6" Key is ≥ V02.01.03.
2. If the issue persists, open the device → Properties → Keyboard tab and confirm Repeat on long press is enabled if operator workflow depends on held keys.

9. Verification and Commissioning Procedure

1. Compile clean — Project → Compiler → All (Software Rebuild). Zero errors, zero warnings is the acceptance criterion. Warnings about deprecated function-key assignments should be resolved, not suppressed.
2. Simulator pass — Start → Runtime → Start Runtime. Click each F-key from the start screen, the middle of the menu tree, and the deepest sub-screen. Confirm the expected action fires in every context.
3. Cross-check the global map — in the project tree, right-click Function Keys and select Cross-reference. Each F-key should show either a global assignment (template) or local assignment(s) on a screen list. No key should be unbound unless intentional.
4. Migration log review — open ProjectMigration.log and resolve every Warning entry. Common warnings: Function key F7 lost during conversion, Screen number rewritten from 5 to 17, ESC key event dropped.
5. Panel transfer — Project → Transfer → Transfer. Choose Serial / MPI / PROFIBUS for a USB PC adapter, or Ethernet if the OP 277 variant supports it. After transfer, perform a power cycle.
6. Operator validation — have the end-user perform a typical work cycle: log in, change language, navigate, log out. Confirm ESC returns to the start screen at every step.

10. Troubleshooting Matrix

11. Frequently Asked Questions