[00:00] In a previous lesson, we learned how alarms can be configured on Ignition Tags to alert Ignition users that there is something wrong in their facility. To configure an alarm on a tag, we simply right click on the tag, select the Edit tag menu and scroll all the way down to the alarming section where clicking on the little pencil will bring up the alarm configuration window. Here, I can add as many alarms as I want on this specific tag, but most importantly, I can define my alarms mode, which allows me to tell the system what condition must be met for my alarm to be considered active. For my pressure tag here, I can set my alarm to have an above setpoint mode and a setpoint value of 50. Now, every time my pressure value goes above 50 PSI, my alarm condition will be met and my alarm will become active.

[01:04] This setpoint value is statically configured to be 50. What I can do instead of a static configuration is bind this setpoint value by clicking on the chain link icon we see here. I can bind the setpoint to either a tags value, or I can define an expression that evaluates to my setpoint value, therefore, making it dynamic. With the tag binding, I have access to every tag in my gateway. And with an expression binding, I have access to the entire Ignition expression language to derive my setpoint value. Now I will close out of my alarm configuration window for just a few minutes. For this example, I want this pressure tag to have two alarms. I want it to have a low pressure alarm and high pressure alarm. But before I configure those alarms, I want to define two memory tags that I will use to configure my dynamic low and high setpoint values.

[02:03] I will click on this plus sign here in the Tag Browser and create a New Standard Memory Tag, which I will name Lo SP and give it a default value of 20, and press OK. I will do the same once more and create a New Standard Memory Tag, which I will name Hi SP and give it a default value of 95 and press OK. Now that I have defined my setpoint tags, I will double click on my pressure tag to bring up its tag editor. I will head down to the alarm section and click on the little pencil to configure my alarms. I want to first create my low pressure alarm. So I'll press the plus sign here and define my alarm to be named low pressure. I will make this a critical alarm and set it's mode to be below setpoint. I will now bind my setpoint to a tag, which tag my Lo SP memory tag that I created earlier.

[03:11] I will now press the plus sign once more to add my second alarm that I will name high pressure. This will also be a critical alarm and we'll have a mode of above setpoint. I will again bind my setpoint value to a tag using the chain link icon as before and selecting my Hi SP memory tag. I will now press Commit to save my alarm configuration and click OK to save everything. Now, my pressure value is set to 50, which is outside my defined alarm range, but I can set my pressure value to say 120. I can see immediately on the right hand side in my Vision alarm status table that my high pressure alarm is now active. I can however, change my Hi SP time's value to say 150 since my pressure value is not above my newly configured setpoint.

[04:12] My high pressure alarm is no longer active. Similarly, if I set my pressure value, just say 10, my low pressure alarm becomes active. I will now configure my Lo SP value to be five. And since my pressure value is not below my newly configure setpoint, my low pressure alarm will no longer be active. Having dynamic setpoints allows you to configure your alarm's active condition by writing two tags or evaluating expressions, instead of having to alter the tags configuration directly.