The Alarm.com System Enhancement Module or SEM marks the first product to integrate Honeywell alarm communications with the Alarm.com platform. The SEM is essentially a glorified 3G CDMA cellular communicator that uses the robust Verizon cellular network to transmit signals from a traditional Honeywell/ADEMCO VISTA low P-series alarm system. This compatibility includes the VISTA-10P, 15P, 20P, 21iP and their First Alert equivalents. The VISTA-20P is one of the most common alarm panels in the United States. There are limitations. The panel must have a manufactured date of 2005 or later. This is printed on the PROM chip located on the board.
Traditionally, Honeywell kept all alarm communication in house with their daughter company, AlarmNet. Although AlarmNet offers similar services to Alarm.com in the form of the Total Connect 2.0 app, Alarm.com offers a wide range of integrations stretching from Nest thermostats to voice activation via Alexa and apple home kit devices.
The SEM wires into ECP keypad bus to the ground and data connections. Generally ECP devices draw power from the VISTA panel's 12VDC output. However the SEM draws from the panel's backup battery. There is a red wire that comes with the device. Inside the cable there is a fuse designed to protect the SEM and alarm panel from any shorts. After you install the SEM, there are some simple changes required before registering with an alarm.com dealer.
The SEM uses keypad address 23 by default so you will want this address to be open and set to partition 1. If it is in use you can change the keypad address by following the steps in the installation manual. Since Alarm.com allows you to manage user codes from the web login and app, you will need to delete all your user codes from the panel. You can add them back at the keypad locally or through the app after it has been setup.