How do I wire the 3G8080 / CD8080 communicator?
The 8080 Alarm.com communicators require using a PCL-422, included with the 8080, as an interface to the control panel. The PCL-422 is connected via a PCLINK ribbon cable to the PCLINK 2 pins on the control panel. The red wire will be oriented to the right on the control panel and be facing to the inside on the PCL-422.
One of the single most common mistakes we encounter is the wiring between the 8080 and the PCL-422. For this you will need 6 conductors. The easy part is the + and - DC wires. The TX and RX connections are where the mistakes are made. The connections are crossed: the RX+ on the PCL-422 goes to the TX+ of the 8080, RX- to TX-, TX+ to RX+, and TX- to RX-