Allen Bradley 1771-A2B 8 Slot I/O ChassisDescription The Allen Bradley 1771 A2B is an 8 slot I O chassis designed for use with PLC 5 programmable controllers. It provides a backplane for mounting and powering up to eight Series A or B I O modules in industrial automation systems. Specifications Model: 1771 A2B Slot Capacity: 8 I O module slots Backplane Current Rating: 8 A total Power Supply Compatibility: Supports 1771 P4S, P5, P6S, and other 24V DC supplies Mounting Type: Panel or rack