The 4DG/2OP module BUS-2/BUS-1 s.m. is used for extension of a MB-Secure- or MB12/24/48/100/256 plus intrusion panel with control and power supply via the BUS. The 4 detector group inputs with reset function allow detectors with hardwired / conventional connection to be integrated to the BUS system (e.g. contacts and passive glass breakage sensors).