Create a WinCC Alarm Logging Message for a Custom PLC Bit
For a custom PLC status such as M100.0, create a message in the WinCC Alarm Logging editor and assign the corresponding WinCC tag as its message trigger; then define the message class/type and event text. The reported procedure also supports creating the message by selecting a tag in the next free Message tag row. The ticket does not state the PCS 7/WinCC version, and a discrete message normally responds to a configured bit being set, so an alarm condition that is active when M100.0 is zero requires an appropriately inverted/conditioned trigger rather than assuming the raw bit's set state means “zero.”
Table of Contents
- Prerequisites and signal semantics
- Create the message in Alarm Logging
- Configure the trigger condition for a zero-state alarm
- Choose message number, class and text
- Compile, activate and test the message
- Alternative PCS 7 alarm engineering
- Version and configuration limits
- Verification
- Limitations and Operational Precautions
- Engineer FAQ
- Technical References
- Related Articles
- Related Tags
Prerequisites and signal semantics
Create or verify the WinCC tag that represents the intended PLC signal and confirm its live value and data type. A bit address such as M100.0 must be mapped to the correct PLC connection/tag in the project. Define the alarm condition precisely: “alarm when the process bit is 0” is different from the message tag's trigger-bit becoming 1. The thread omits WinCC version, tag type and the exact trigger configuration.
Create the message in Alarm Logging
The source-provided workflow is: open the Alarm Logging editor; in the navigation tree select the message class/type folder; in the table select the first unused row in the Number column and enter an unused message number; enter the event/message text and edit message properties. Alternatively, select the WinCC tag in the first free Message tag row; the reply says Alarm Logging creates a message with the next available number and uses that tag as the message tag. Exact labels and behavior can vary by version, so confirm them in the matching manual.
Configure the trigger condition for a zero-state alarm
A bit-triggered message uses a configured trigger bit. Siemens' WinCC V7.5 Getting Started search result describes a discrete alarm as triggered when the selected tag bit is set, but its PDF could not be opened during research. If the alarm must be active when M100.0 is zero, do not assume the raw bit's set state is the desired trigger. Use a signal whose asserted state represents the alarm condition—such as a deliberately defined inverted status in PLC logic—or a documented WinCC condition mechanism supported by the deployed version. Verify the chosen implementation with the controls engineer before deployment.
Choose message number, class and text
Assign the message to the intended message class and type and choose a number not already in use. The source reply lists historical ranges reserved for WinCC system messages, but the deployed release's manual is needed to confirm current ranges. Use a concise event text that clearly identifies the condition and its equipment/area; avoid a generic phrase such as “High Limit Reached” unless it accurately describes the bit's meaning.
Compile, activate and test the message
Apply the OS project's normal compile/update procedure for the installed release. During a controlled test, exercise the input through both the normal and alarm states and verify that the correct message enters and leaves the Alarm List with the expected text, class, time and acknowledgement behavior. Confirm that the message follows the intended zero-state condition rather than merely checking that a row exists in Alarm Logging.
Alternative PCS 7 alarm engineering
For a production PCS 7 project, determine whether the signal should be implemented using the project's standard PCS 7 alarm mechanisms rather than a standalone WinCC message. The supplied discussion specifically addresses a custom WinCC tag in Alarm Logging; it does not compare that method with AS-generated/program messages or establish project standards.
Version and configuration limits
The ticket does not identify PCS 7, WinCC, OS architecture, tag data type, alarm class, message number or whether the trigger is PLC- or WinCC-side. The procedure is therefore a classic Alarm Logging workflow reported in the source, not a verified click-by-click sequence for a named release. Current WinCC configuration may use different editors and capabilities.
Verification
Monitor the source bit, its WinCC tag and the Alarm List together. Verify the alarm occurs when the intended condition is true, clears when the condition returns to normal, and carries the selected message text/class. Test acknowledgement and alarm-history behavior only as required by the project design. Verify the alarm in the correct OS Runtime and client context.
Limitations and Operational Precautions
The reply was acknowledged as helpful, but the source gives no screenshot, target version or final test results. The tag M100.0 is only the user's example; do not publish or configure that address without confirming it belongs to the actual project. Alarm configuration changes affect operator annunciation and must follow site alarm-management and change-control practices.
Engineer FAQ
Can I create a WinCC Alarm List message from a custom tag? The source procedure uses a WinCC tag as the message tag in Alarm Logging and defines the message text and properties.
How do I make the alarm active when M100.0 equals zero? Ensure the configured trigger represents the zero-state alarm condition; a bit message triggered by a set bit may need an inverted/conditioned signal. Confirm behavior in the installed WinCC version.
Where is the event text entered? The source reply says to enter the text in the Event column or edit it in the message properties; labels can vary by version.
Can I choose any message number? Use an unused number allowed by the installed release; system-reserved ranges differ by product/version and should be verified.
How do I know the message works? Exercise normal and alarm states and verify the incoming/outgoing message, text, class and timing in the Alarm List.
Technical References
- Siemens, SIMATIC HMI WinCC V7.5 Getting Started, section on configuring discrete alarms in Alarm Logging; states that a discrete alarm is triggered when a bit in the tag value is set. Official PDF could not be opened during research (HTTP/content-size failure): https://cache.industry.siemens.com/dl/files/620/109792620/att_1051915/v1/GettingStartedenUS_en-US.pdf
- Siemens, SIMATIC HMI WinCC V7.5 – WinCC/Options for Process Control, System Manual, 09/2018, A5E45518224-AA, alarm behavior and PCS 7 message classes: https://cache.industry.siemens.com/dl/files/757/109760757/att_962240/v1/WinCC_ProcessControl_en-US_en-US.pdf