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Application Note: How to Triger a Digital Alarm Using a PLC Tag in FactoryTalk View?

You can read this post on LinkedIn as well.

Introduction:

Ah, FactoryTalk View, the realm of alarms and triggers—a landscape where digital statuses flicker and cause headaches aplenty. Today, we embark on a journey to unravel the mysteries of alarm triggers in this enigmatic realm. Join me as we navigate the realm of Value, Bit, and LSBit triggers, and discover the unexpected twists and turns that await us. Brace yourselves, fellow adventurers, for we delve into the captivating world of FactoryTalk View!

Section 1: The Curious Case of Digital Alarms

In our quest for alarm enlightenment, we stumble upon three intriguing types of triggers: Value, Bit, and LSBit. Intuitively, one might assume that digital alarms should employ Bit triggers—the natural choice for binary states of on (1) or off (0). However, hold onto your hats, for a revelation awaits! Rockwell Automation Technical Support, unveils the surprising truth: Value triggers are the key to digital alarm mastery. Prepare to have your assumptions shattered!

Section 2: Unveiling the Value-Triggered Twist

As we peer into the depths of digital alarm configuration, a startling realization dawns upon us. The digital alarm's trigger lies not in a simple on/off state, but rather in the realm of values. Yes, you read that correctly! A digital alarm is triggered by the elusive value of 1—setting the stage for a captivating journey of alarm activation. Behold the second highlighted sentence below, where the truth reveals itself in all its glory. A twist worthy of a dramatic plot twist!

A digital alarm status is either On (1) or Off (0) unless you want to have multiple discrete statuses (state 0, state 1, state 2, state 3, etc.).

Figure 1 Value Trigger Type Alarm

Section 3: The Bit Trigger's Secret Role

Though the Bit trigger may not suit our digital alarm ambitions in the first use case, it still holds a vital role within the FactoryTalk realm. Picture this: a Logix Designer PLC program boasting a magnificent double integer (DINT) with its impressive 32 bits. Ah, the possibilities! Within these 32 bits, lies the power to create 32 collective alarms, waiting to be commanded within the FactoryTalk HMI program. But heed this caveat, dear adventurer—the distinction between Trigger Value and Bit Address. You have to put Trigger Value (Bit Position) into the setting after choosing the Value-triggered alarm type.

No alt text provided for this image
No alt text provided for this image

Section 4: The Manual Manifestation of Alarm Tags

Alas, there exists no systematic pathway to bring forth your Alarm tags into FactoryTalk View. Brace yourselves for the task at hand—for manual addition of each tag beckons. One by one, they shall grace the interface, claiming their rightful place in the realm of alarms. Prepare your patience, fellow troubleshooters, for a manual journey lies ahead!

Conclusion:

We navigate a realm where digital alarms defy convention, triggered not by mere bits but by values. The Bit trigger, though not fitting our initial purpose, reveals its hidden powers in other realms of automation. And let us not forget the arduous path of manually adding Alarm tags—a true test of patience and diligence.

Personal Note:

After reflection, I think the multi-state digital alarm is the fundamental reason why Rockwell Automation's Software Engineer choose to trigger them by "Value." If I were the Engineer, I would probably categorize them into "State," Value, Bit, and LSBit.

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