Enabling Operator Input Request Messages (Bedienanforderung) on APL Block MonDiL in SIMATIC PCS 7

In SIMATIC PCS 7 Advanced Process Library (APL), configuring an Operator Input Request message (Bedienanforderung) on digital monitoring block MonDiL (FB1848) requires unchecking the 'With acknowledgment' (Mit Quittierung) attribute in the block message configuration dialog. By default, MonDiL assigns alarm and warning classes that demand mandatory operator acknowledgment. Because Operator Input Requests are informational prompt messages that do not follow standard alarm acknowledgment protocols, the engineering interface hides the 'Bedienanforderung' message class until 'With acknowledgment' is deselected. Once unchecked, the message class dropdown unlocks 'Bedienanforderung' and 'Status Message' options.

Message Classification Architecture in SIMATIC PCS 7 APL

In SIMATIC PCS 7, alarm management conforms to international standards (ISA-18.2 / IEC 62682) by categorizing process events into distinct Message Classes. The Advanced Process Library (APL) block MonDiL (FB1848) monitors digital process signals and generates WinCC messages using the integrated Alarm_8P mechanism.

The engineering system classifies messages into two primary behavioral groups:

Message Behavioral CategoryTypical Message ClassesAcknowledgment Required?Operational PurposeProcess Alarms / FaultsAlarm (High/Low), Warning, AS Control FaultYes (Mandatory)Alerts operator to abnormal process limits or equipment tripsOperator Prompts / StatusBedienanforderung (Operator Input Request), Status MessageNo (Unacknowledged)Prompts operator to perform manual field actions (e.g., open bypass valve)

Because an Operator Input Request is designed to prompt an action rather than report an unacknowledged equipment fault, WinCC treats it as a non-quittierbare (non-acknowledgment) event.

Why Operator Input Requests Require Unchecking Acknowledgment

When an engineer opens the message configuration dialog for MonDiL in CFC (Object Properties -> Messages), the message class dropdown list appears to offer only standard alarm types: Alarm, Warning, Tolerance, AS Process Control Fault, OS Process Control Fault, Preventive Maintenance, and Process Message. The option Bedienanforderung (Operator Input Request) is conspicuously absent from the selection list.

This behavior is caused by dialog filtering based on the acknowledgment attribute:

Every individual message row within Alarm_8P contains a boolean flag: 'With acknowledgment' (Mit Quittierung).
By default, all message channels on APL blocks have this flag checked.
The STEP 7 / CFC Message Configuration Editor dynamically filters the Message Class dropdown list based on this checkbox. If 'With acknowledgment' is enabled, the editor hides all message classes that are defined in WinCC as non-acknowledging.
To make Bedienanforderung selectable, the engineer must scroll horizontally across the table grid and deselect the checkbox.

Step-by-Step Configuration Workflow on MonDiL

To configure MonDiL to generate an Operator Input Request prompt message, execute the following technical procedure:

Open CFC and Locate MonDiL Block: Open the Continuous Function Chart containing the target MonDiL instance.
Open Message Configuration Dialog: Right-click the MonDiL block and select Object Properties. Click the 'Messages...' button.
Navigate to the Target Message Identifier: Select the message line intended for the operator request (e.g., SIG_1 or an auxiliary digital monitoring input).
Deselect 'With Acknowledgment' Checkbox: In the message grid, scroll horizontally to the right until the column labeled 'With acknowledgment' (or Mit Quittierung in German MUI) is visible. Uncheck the checkbox for that specific message line.
Select Bedienanforderung Message Class: Click the Message Class dropdown in that row. The dropdown now displays the previously hidden classes. Select 'Bedienanforderung' (or Operator Input Request in English systems).
Configure Message Text: In the Event text column, enter the explicit operator instruction (e.g., Prompt: Verify local cooling water valve open).
Compile and Download: Save the dialog. In CFC, execute Chart -> Compile -> Chart as Program -> Changes Only and download to the AS controller. Run an OS compilation (Compile OS -> Changes Only) to propagate the message attributes into WinCC Alarm Logging.

Verification

Verify the proper configuration and runtime display of the Operator Input Request through these diagnostic steps:

WinCC Alarm Logging Verification: Open WinCC Explorer on the OS Server. Open Alarm Logging. Locate the compiled message ID corresponding to the MonDiL block. Confirm that its Message Class is listed as Operator Input Request with acknowledgment disabled.
Simulate Digital Input Transition: In CFC Test Mode, force the input signal In connected to MonDiL to activate the message.
WinCC AlarmControl Window Display: Observe the top alarm line and the main AlarmControl window in WinCC OS Runtime. Confirm that the message appears in white/blue (standard prompt color), displays the prompt text, and clears automatically when the input condition resets without requiring the operator to click the Acknowledge (Quittieren) button.

Limitations and Operational Precautions

When deploying Operator Input Requests, observe these alarm management standards:

Do Not Misuse for Critical Safety Alarms: Never classify critical process safety trips or interlocks as Operator Input Requests. Safety events must always use acknowledging alarm classes (Alarm - High, Alarm - Low) to enforce operator accountability.
Alarm Horn Configuration: Verify WinCC Horn configuration. Operator Input Requests should typically be routed to an intermittent chime or silent notification rather than continuous audible sirens reserved for emergency alarms.
EEMUA 191 Alarm Flood Prevention: Limit the use of operator prompt messages to true operational change requests; overusing prompts creates operator cognitive fatigue and contributes to alarm flooding.

Engineer FAQ

Why is the 'With acknowledgment' column hidden by default in the message dialog?

The column is located on the far right of the table grid. If the SIMATIC Manager message window is sized to default width, the horizontal scrollbar must be used to bring the acknowledgment checkbox into view.

Can I configure an Operator Input Request on analog blocks like MonAnL?

Yes. The same Alarm_8P message configuration mechanism exists on MonAnL and PIDConL. Unchecking 'With acknowledgment' allows assigning prompts to limit violations.

Does an Operator Input Request require a button click to disappear?

No. By definition, unacknowledged prompt messages remain visible in the active message list only as long as the triggering state persists. When the field signal returns to normal, the message clears automatically.