Activating the Lock and Unlock Alarm Buttons in WinCC AlarmControl - Toolbar Properties and Operator Permissions

When the Lock/Unlock buttons (message suppression and lock/hide operations) in the WinCC AlarmControl toolbar are grayed out or inactive in SIMATIC PCS 7 OS Runtime, two independent configuration layers must be validated. First, in WinCC Graphics Designer, open the WinCC AlarmControl Properties dialog, navigate to the Toolbar tab, ensure 'Lock message' (Button ID 10) and 'Unlock message' (Button ID 11) are checked, and verify that their assigned Authorization Level matches the operator's clearance. Second, verify that the logged-in Windows or WinCC user possesses Authorization Level 6 ('Higher process controlling') or Level 7 ('System management') in WinCC User Administrator. Without sufficient authorization assigned to @CurrentUser, the runtime security engine automatically disables these operational buttons.

WinCC AlarmControl Toolbar Architecture: Button States and Authorization Constraints

In SIMATIC PCS 7 OS, the central alarm management interface is implemented using the WinCC AlarmControl (.NET/ActiveX control embedded in standard process screens and template PDLs such as @alarm.pdl and @overview1.pdl). The AlarmControl toolbar provides discrete operational buttons for acknowledging, sorting, filtering, selecting, locking, and hiding alarm messages.

The Lock and Unlock buttons serve critical plant operations by allowing qualified operators to suppress nuisance alarms or lock out faulty instrument tags during commissioning, maintenance, or shutdown intervals. When an operator observes that the Lock (padlock icon) or Unlock button is inactive (grayed out), the WinCC runtime engine is preventing message manipulation due to one of three conditions:

Toolbar Button Parameterization: The button is physically disabled, hidden, or assigned to a non-existent authorization group within the control's design properties.
User Authorization Mismatch: The active user session (@CurrentUser) lacks the specific numeric authorization level configured on the button in WinCC User Administrator.
Incompatible Alarm View Context: The AlarmControl is currently displaying an archive list (such as the Long-term Archive List or the Hit List) rather than an active message list (Journal, Incoming Alarm List, or Process-relevant Alarm List). In historical archive views, locking operations are mathematically and logically invalid because historical archive records cannot be retroactively locked.

Configuring Toolbar Buttons and Authorization Levels in Graphics Designer

To configure the Lock and Unlock buttons within template or custom process graphic pictures, engineers must inspect the control attributes in WinCC Graphics Designer:

Open the target picture (e.g., custom alarm screen or @alarm.pdl) in Graphics Designer on the Engineering Station (ES).
Double-click the WinCC AlarmControl object to open its configuration dialog.
Select the Toolbar tab. Under the 'Buttons' section, locate:
Button 10: Lock message (suppresses the selected message from the active alarm list and places it in the locked messages buffer).
Button 11: Unlock message (restores a previously locked message back to active monitoring).
Ensure the Active checkbox is ticked for both buttons so they render on the runtime toolbar ribbon.
Inspect the Authorization field assigned to each button. By default in standard WinCC, authorization may be set to 'No authorization' or linked to standard PCS 7 authorization levels. In PCS 7 environments, it is typically linked to Authorization 6 ('Higher process controlling') or Authorization 7 ('System management'). If an authorization level is configured, any operator without this right will see the button in a permanent disabled/grayed-out state.

WinCC User Administrator Privileges for Alarm Suppression

WinCC User Administrator governs operator interaction across the distributed client-server architecture. When a client station displays alarms, user rights are evaluated against the local or centralized user database:

Authorization Level 5 (Process controlling): Grants standard operations such as setpoint adjustments, manual/automatic switching, and alarm acknowledgment (Acknowledge single message / Acknowledge visible messages).
Authorization Level 6 (Higher process controlling): Grants operational overrides, including parameter limits tuning, interlock bypassing, and locking/unlocking alarm messages.
Authorization Level 7 (System management): Grants administrative access, OS client shutdown, runtime diagnostics, and system-wide archive configuration.

If the operator logs in with basic Level 5 privileges, the Lock/Unlock buttons remain locked out to prevent unauthorized alarm hiding that could conceal critical plant safety conditions. Furthermore, if WinCC WebNavigator or WinCC OS Clients are used, the user group must have the corresponding authorization level mapped in the picture hierarchy or area rights.

AS-Level Message Locking (MsgLock) vs OS-Level Alarm Hiding

Engineers must distinguish between OS-level alarm locking in WinCC AlarmControl and AS-level message suppression within the PCS 7 Advanced Process Library (APL):

OS AlarmControl Locking: The message continues to be processed and signaled by the S7-400 CPU via ALARM_8P blocks. The WinCC Alarm Logging subsystem intercepts the message at the OS server and places it into the 'Locked Message List' without annunciating it on the operator screens or horn. This is an HMI-level suppression mechanism.
APL MsgLock (AS Level): Technological blocks (e.g., MotL, VlvL, MonAnL) feature input parameter MsgLock = 1. When MsgLock is set via CFC interconnection or operator faceplate command, the CPU internally inhibits calls to ALARM_8P, preventing message generation entirely. This reduces CPU communication overhead on the Industrial Ethernet bus.
Smart Alarm Hiding (State-Based Hiding): WinCC also supports manual and automatic alarm hiding based on plant operating states (e.g., hiding motor underspeed alarms when the unit is stopped). Hiding uses the 'Hide message' button rather than 'Lock message'.

Comparative Parameter Matrix: Alarm Suppression and Locking Properties

The following table compares the configuration parameters, operational behaviors, and diagnostic indicators for alarm locking in WinCC:

Feature / ParameterLock Message (Button ID 10)Unlock Message (Button ID 11)APL MsgLock ParameterSmart Alarm HidingExecution SubsystemWinCC OS Alarm LoggingWinCC OS Alarm LoggingAS CPU (ALARM_8P Execution)WinCC OS Alarm LoggingConfiguration ToolWinCC Graphics DesignerWinCC Graphics DesignerCFC Editor / APL FaceplateAlarm Logging / Filter EditorDefault Auth LevelLevel 6 / Level 7Level 6 / Level 7Level 6 (Op_Level / Feature bit)Level 5 or Level 6Runtime LocationAlarmControl ToolbarAlarmControl ToolbarAPL Standard/Param ViewAlarmControl Hide ButtonTarget Archive/ViewActive Alarm JournalLocked Messages ViewSuppressed at ControllerHidden Alarm ListCPU Cycle OverheadUnchanged (Messages Sent)Unchanged (Messages Sent)Eliminated (ALARM_8P idle)Unchanged (Filtered at OS)Typical ApplicationInstrument MaintenanceRestoring Cleared FaultsEquipment Static Out-of-ServicePlant Operating State Masking

Step-by-Step Procedure to Enable and Authorize Alarm Locking Buttons

Follow this engineering procedure to resolve inactive Lock/Unlock buttons in WinCC AlarmControl:

Check Logged-In User Authorization:
- On the running OS Client or Single Station, inspect the @CurrentUser tag in the status bar.
- If no user is logged in, log in with an engineering or supervisor account possessing Level 6/7 rights.
- If the buttons immediately become active, the issue was purely insufficient user privileges. Open WinCC User Administrator on the ES, select the operator user group, and grant Authorization Level 6 ('Higher process controlling') for the relevant plant areas.
Verify WinCC AlarmControl Configuration:
- On the ES, open SIMATIC Manager, navigate to the OS project, and open Graphics Designer.
- Open the screen hosting the alarm control (e.g., @alarm.pdl or your custom process picture).
- Right-click the WinCC AlarmControl and select Properties (or double-click the control).
- Click the Toolbar tab.
- In the button list, scroll down to find Lock message and Unlock message.
- Verify that both checkboxes under Active are selected.
- Check the value in the Authorization column. If set to an elevated level not assigned to operators, adjust it to the designated plant security level or 'No authorization' (if area security is managed elsewhere).
Ensure Active Alarm View Mode:
- In the AlarmControl properties, click the Message lists tab.
- Confirm that the default view is set to Message list (Incoming alarms) rather than Long-term archive or Short-term archive.
Save and Deploy:
- Save the picture in Graphics Designer.
- Download the OS changes or perform OS Project Editor update if modifying system template pictures.
- Activate Runtime and verify button responsiveness.

Verification

Validate the configuration by executing the following functional checks:

Log into WinCC OS Runtime with an account that has Authorization Level 6 or higher.
Navigate to the alarm overview screen. Select an active, non-critical process alarm in the WinCC AlarmControl.
Verify that the Lock message toolbar button (padlock icon) is highlighted and clickable.
Click Lock message. Confirm that the selected alarm disappears from the incoming alarm list and transfers into the Locked Messages view.
Switch the AlarmControl view to 'Locked Messages List' (Button ID 14). Select the locked message and click Unlock message.
Confirm the alarm returns to the active monitoring list.
Log out or log into an unprivileged operator account (Level 5 only) and verify that the Lock and Unlock buttons return to their disabled, grayed-out state, confirming security compliance.

Limitations and Operational Precautions

Locking Safety-Critical Alarms: Locking alarms suppresses visual and acoustic annunciation. Plant administrative policies must strictly regulate who has Authorization Level 6 to prevent operators from inadvertently masking critical safety or ESD interlock trips.
System Templates vs Custom PDLs: Modifying standard template screens (@alarm.pdl, @overview1.pdl) directly in Graphics Designer may result in customizations being overwritten when the OS Project Editor is re-run. To persist changes, modify templates in the OS Project Editor configuration or create a dedicated custom alarm graphic.
Audit Trail Logging: All locking and unlocking actions generate operator audit messages in the WinCC archive. Ensure audit logging is active to meet regulatory and incident-investigation requirements.

Engineer FAQ

Why is the Lock button visible and active, but clicking it does nothing?

This typically occurs if the operator has selected a message row that is already locked, or if the selected message belongs to an area where the operator has view-only rights but lacks operational write permissions. Check the user's Area Authorization assignments in WinCC User Administrator.

Can locked alarms be viewed on WebNavigator clients?

Yes. WinCC WebNavigator supports standard WinCC AlarmControl views, including the Locked Messages List, provided the WebNavigator client has the requisite user permissions and WebNavigator components are updated to match the WinCC server release.

What is the difference between Locking a message and Acknowledging a message?

Acknowledging an alarm informs the system that an operator has seen the event; if the fault persists, the alarm remains in the alarm list with an 'Acknowledged' state. Locking an alarm removes the alarm completely from active operational displays and suppresses all acoustic annunciations until manually unlocked.

How can I lock an alarm automatically from an S7-400 CFC chart?

Use the technological block's input parameter MsgLock (for APL blocks such as MotL, VlvL, MonAnL). Setting MsgLock = 1 prevents the block from triggering ALARM_8P message routines in the controller.

Does running OS Project Editor restore disabled Lock/Unlock buttons?

Yes. If the Lock/Unlock buttons were removed from standard templates, running OS Project Editor with default settings restores the factory Siemens @alarm.pdl template, resetting toolbar button configurations to standard defaults.