The Interlogix TX-E221 is a recessed door and window sensor designed for use with Interlogix Alarm Systems like the Simon XT. The sensor and its accompanying magnet are inserted into holes that are drilled into the door or window and its frame. The magnet goes inside the door or window (moving part), and the sensor goes inside the frame (stationary part to avoid damage to the board). When the door or window is opened, the magnet will separate from the sensor, causing the reed switch to actuate and open the internal circuit. The sensor will then send a signal to the alarm system to perform a predetermined response based on how the zone is programmed during enrollment.
As a recessed sensor, the Interlogix TX-E221 is entirely invisible when the door or window is closed. This is pleasing to many users who want a discreet installation. However, the process of drilling holes in the door or window and its frame can be inconvenient or impossible for some users. Also some windows and doors will void the warranty if you drill into them. In those cases, it is better to use a surface-mount door and window contact. These devices operate in the same manner, but they go on the outside of the door or window. But for the most discreet installation possible, the TX-E221 is simply unmatched. For the best possible performance, the magnet should be within a half inch of the sensor whenever the door or window is closed. Make sure to align the holes for the sensor and the magnet properly when executing the installation.
Like most other wireless Interlogix Sensors, the TX-E221 communicates at a wireless frequency of 319.5 MHz. This makes it compatible with any Interlogix Simon Alarm System, as well as any Qolsys Alarm System equipped with a 319.5MHz daughtercard. The sensor can be learned-in automatically with any of these panels through system programming. The TX-E221 also comes included with its own CR2 lithium battery that will require replacement roughly every five years depending upon usage. Overall, the TX-E221 is a fantastic door and window contact for an invisible installation.