10100/2/1CC10900 HONEYWELL Horizontal BUS Driver Product Description The Honeywell 10100/2/1 CC10900 Horizontal Bus Driver (HBD) is a module used in Honeywell’s automation or distributed-control systems (DCS) I/O architecture.It is described as a “Horizontal Bus Driver” module — i.e., a card/module that interfaces the vertical backplane to the horizontal bus in an I/O rack.It consists of two parts — the electronic part (10100/2/1) and a flat cable (such as A1, A21 or A22)