The Allen-Bradley 1754-L28BBB is a 28 I/O safety controller. It is one of Allen-Bradley’s GuardPLC 1200 Control System devices. It is built according to the IEC 61508 (SIL 3) and ISO 13849-1 (PLe/Cat. 4) standards to feature a fail-safe CPU. This controller is used to detect faults that can cause loss of safety functions within the safety time you program. The Allen-Bradley 1754-L28BBB reacts differently to different kinds of errors but it always tends to react in a safety-related way. The controller performs actions when it detects controller errors, permanent errors, and transient errors.

The basic tools for processing safety logic modules on this device are 20 digital inputs, 8 digital outputs, and 2 high-speed counters. For communication and programming purposes it is equipped with an RS-232 serial port and an Ethernet port. On the front panel, users can watch inputs and outputs status over signaling lamps. There are also 6 more signaling lights – the RUN, PROG, ERROR, FORCE, FAULT, and COMM lights. Users can also access the backup battery compartment from the front side of the controller. The Allen-Bradley 1754-L28BBB must be supplied with 24 Volts DC power that can deliver at least 8 Amps. The dimensions of the controller are 160 x 112 x 90 millimeters (6.3 x 4.41 x 3.54 ). The item weighs 0.68 kilograms (1.5 pounds).