Tyco bought Simplex Time Recorder Company on January 5, 2001, for US$1.15 billion and merged it with Grinnell Fire Protection, forming SimplexGrinnell.

The main manufacturing facility was in North Carolina at the Grinnell Company-General Fire Extinguisher Company Complex.

Most of Simplex's audible notification appliances prior to the 1990s were relabeled Benjamin Electric, Federal Signal, Faraday, and Autocall devices.

Simplex's time-division began to lose market share, but their newly founded fire alarm division significantly prospered.

In 1979, Simplex introduced the industry's first networked multiplex building control system that was capable of handling fire alarm, security, HVAC, synchronized time, and watchman's tour.

They also provide testing, inspection, and maintenance services for fire alarm, sprinkler, suppression, security, and communication equipment.