The 1771-LC5B controller is a 24 Volts DC loop controller device made by Allen-Bradley/Rockwell Automation. It is an intelligent I/O module is a PLC 5 device. It comes with a W/RTD option. This Series A device supports different voltage ranges. The typical AC signal delay and DC signal delay are 45 milliseconds and 50 milliseconds, respectively. The loop controller can be rack mounted. A built-in microprocessor controls the operation of this loop controller device. The 1771-LC5B controller helps to monitor and direct various application processes. For communication, it uses the DH-485 protocol. The front panel of the loop controller comes with a display unit along with some functional keys. The display unit is an LCD panel which can display alphanumeric values and graphs. There are status indicators present in the panel. The function of the keys is user-configurable.

The Allen-Bradley 1771-LC5B controller is able to accept frequency and analog inputs easily. The controller is equipped with an open collector transistor for contact ratings of 250 milliamps. This Allen-Bradley controller is capable of block transfer by using the 1771 I/O structure. The communication between the discrete analog module and the processor is bidirectional. The processor helps to block transfer output data through the image table. The 1771-LC5B controller supports high power operations and exhibits a long life. This loop controller device supports the input filtering which may occur due to electrical noise. It supports the natural binary format and it can sense up to 16 single-ended or 8 differential analog inputs. It offers real-time sampling.