The PC4020 is a 16 zone panel which is expandable to 128 zones. Expansion can be accomplished over a 4-wire Combus using a variety of input/output and functional modules. The base panel includes two addressable loops which can accommodate up to 112 addressable input devices and the system can also be expanded with a 64 zone wireless receiver which connects to the system via the 4-wire Combus. Addressable, hardwired and wireless expansion can be used in any combination that suits the application. The MAXSYS is software ready to implement all the security, access control, automation and residential fire functions by simply adding conventional or addressable devices, access control modules, and automation interface components.