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ADC-SEM300-VT-AT - Alarm.com SEM Dual-Path Ethernet/Cellular AT&T LTE Alarm Communicator (for Honeywell VISTA Panels)

ADC-SEM300-VT-AT - Alarm.com SEM Dual-Path Ethernet/Cellular AT&T LTE Alarm Communicator (for Honeywell VISTA Panels)
ADC-SEM300-VT-AT - Alarm.com SEM Dual-Path Ethernet/Cellular AT&T LTE Alarm Communicator (for Honeywell VISTA Panels)
Item# ADC-SEM300-VT-AT

Please Note: The Alarm.com ADC-SEM300-VT-AT dual-path ethernet/cellular AT&T LTE alarm communicator has been discontinued and replaced by the ADC-SEM300-VT-AT-M model number.

Alarm.com ADC-SEM300-VT-AT Product Description:


The Alarm.com ADC-SEM300-VT-AT is a dual-path system enhancement module (SEM) designed to migrate compatible Honeywell/Ademco VISTA-10P, VISTA-15P, VISTA-20P and VISTA-21iP panels to Alarm.com's award-winning interactive services. The ADC-SEM300-VT-AT dual-path SEM supports the AT&T 4G LTE cellular network and optional broadband ethernet. The multiple paths ensures the longest life cycle with the most secure and reliable service. The SEM is now ETL certified, ensuring a high benchmark of safety and sustainability.

The SEM300 enable wireless reporting of alarms and other system events using the LTE wireless (cellular) network and Broadband Ethernet. With the SEM300 you can configure and support installations from any browser or smartphone using Alarm.com's familiar and easy-to-use web and mobile support tools, including the Partner Portal and MobileTech app. And, enable Alarm.com interactive monitoring and alerting for end-users. Lastly, you can integrate Alarm.com's home automation and energy management services with the SEM's built-in Z-Wave Plus capabilities.

For remote programming to be available, the panel must support the downloader feature. This feature is available on most panels with a minimum of v5.2. The SEM300 is compatible with Honeywell/ADEMCO panels and the equivalents, dating back to 2005. The Honeywell/ADEMCO VISTA-21iP is also compatible when the Internal IP/GSM jumper switch is set to the OFF position.

Product Features:

  • Fast, reliable, and secure wireless signaling
  • Cellular 4G AT&T LTE primary communication path
  • Broadband as an optional secondary communication path
  • Remote monitoring and control using the website and app
  • Remote panel configurations with Uploader/Downloader, including Add Sensors
  • Remote access and management of locally saved user codes
  • Home automation and energy management
  • Support for Z-Wave Plus devices
  • Video monitoring
  • Cover and wall tamper included
  • Externally facing LEDs for visual feedback
  • Internal Antennas
  • No separate power supply needed
  • Over the air (OTA) upgrades
  • CID and SIA central station signaling
  • Enable Alarm.com interactive monitoring and alerting for end users
  • ETL Listed to UL985, UL1023 and ULC S545
  • Configure and support installations from any browser or smartphone using Alarm.com's familiar and easy-to-use web and mobile support tools, including the Partner Portal and MobileTech

Alarm.com ADC-SEM300-VT-AT Product Specifications:


  • Enclosure Dimensions (L x W x D): 7.66 x 4.35 x 1.65 in. (19.46 x 11.05 x 4.19 cm)
  • Enclosure Color: White
  • Case Material: Fire-retardant PC/ABS, PC
  • Compatibile: Honeywell/Ademco VISTA 10P, 15P, 20P and 21iP panels (manufactured 2005 or later and version 3.1+)
  • Not Compatible: POTS. The SEM should be the only communication path for alarm signaling to the GeoArm monitoring station.
  • Power Requirements: 12 V nominal, 125 mA nominal (continuous), 230 mA max
  • Cellular Network: AT&T 4G LTE with 3G HSPA, 2G GSM fallback
  • Panel Interfaces: Two keypad BUS connections, 12 V power and ground
  • Enclosure Interfaces: Five LEDs (red, green, yellow, or blue)
  • Alarm.com Module Indicators: One module/panel communication status LED, one module power LED, one automation LED, three wireless communication status LEDs
  • SEM Circuit Board Indicators: One LAN LED, one processor LED, one COMM fail LED
  • Z-Wave Frequency: 908.4 MHz
  • Operation temperature: 14° - 131° F (-10°C - 55°C)
  • Storage temperature: -30° - 140° F (-34°C - 60°C)
  • Humidity: 90% relative humidity, non-condensing

Alarm.com ADC-SEM300-VT-AT Recommended Tools:


  • Screwdrivers: Small blade and Phillips
  • Drill and bits for screws and/or wall anchors
  • Ethernet cable
  • Alpha keypad (not required) - Alarm.com strongly recommends installing an alpha keypad to ensure the failure to communicate (FTC) trouble condition is displayed to the user.
  • Four-conductor, 22 AWG or larger stranded wire (Maximum wire length of 40 feet)

Alarm.com ADC-SEM300-VT-AT Product Compatibility:


  • Honeywell/ADEMCO VISTA-10P
  • Honeywell/ADEMCO VISTA-WA10P
  • Honeywell/ADEMCO VISTA-10PSIA
  • First Alert FA130CP
  • First Alert FA130CPSIA
  • Honeywell/ADEMCO VISTA-15P
  • Honeywell/ADEMCO VISTA-WA15P
  • Honeywell/ADEMCO VISTA-15PSIA
  • First Alert FA148CP
  • First Alert FA148CPSIA
  • Honeywell/ADEMCO VISTA-20P
  • Honeywell/ADEMCO VISTA-WA20P
  • Honeywell/ADEMCO VISTA-20PSIA
  • First Alert FA168CPS
  • First Alert FA168CPSSIA
  • Honeywell/ADEMCO VISTA-21iP (Important: The SEM300 is compatible with the VISTA-21iP, if the Internal IP/GSM Jumper is set in the OFF position. Verify the SEM is powered down before setting the jumper to OFF.)
Q & A's :

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