The Door Interface Unit (DIU 210) is designed primarily to provide power to a door lock, as well as local power to a CEM reader when a high level of security is required. It has onboard inputs which can be used to monitor conditions such as a fire alarm or activated Break-glass condition. 

The DIU 210 improves door security, by allowing the installer to locate lock controls on the secure side of a door, with an intelligent CEM reader on the unsecured side. The DIU 210 communicates with an intelligent CEM reader over a single pair RS485 cable. Upon a valid swipe at the card reader, the reader will instruct the DIU (over the RS485 communications channel) to activate the appropriate output to release the lock using a coded data signal (i.e. coded lock).