Product Description:

The X20BB77 is a carrier module produced by B&R Automation for the X20 Fieldbus Input Output Modules series. Within an automation rack, it provides the physical base that supplies fieldbus power and signal access for connected slices, allowing distributed I/O to be wired onto a single backplane and linked to the controller through CAN or serial links. This base allows individual I/O slices to be swapped or expanded without disturbing field wiring, which supports modular production cells.

The module draws only 1.17 W from the system bus, so heat rise inside the cabinet is minimal when several bases are mounted side by side. All connected electronics receive an I/O supply of 24 VDC, which is the standard low-voltage level for sensors, coils, and solid-state outputs in industrial panels. A single CAN trunk is routed through the backplane, and its segment is terminated on the base by an integrated resistor, eliminating the need for an external plug-in terminator. The bus current that can be routed through each spring terminal is rated for a maximum of 10 A, so high-density output slices can be energized without additional feeds. The base includes one CAN port for the network, and status LEDs indicate traffic to assist with field diagnostics.

Up to 2 interface module slots are provided on the backplane, so bus couplers or power infeed modules can be positioned where cable routing is convenient. Slot spacing follows a pitch of 87.5 ± 0.2 mm, enabling precise alignment on standard DIN rails. The enclosure has an IP20 protection rating, which means fingers and tools are guarded but the module must be installed in a closed cabinet. It can be fastened in either horizontal or vertical orientation to suit panel layout. Communication with legacy devices is supported through 1 RS-232 port located on the left-hand interface plate.