EarthX has a monitor function with a dedicated lead that is intended to go to an annunciator lamp or LED. I don't recall the voltage, but it isn't 12v. I have two of them in my RV-10. Both monitor leads are run to an input pin on the EFIS. There are three of these input ports on each screen (if you have more than one). You can configure the text message that appears on the screen and whether the alert is triggered by going high or low.