1772-LI

The 1772-LI Processor Control Module belongs to the 1772 Series of industrial PLC-2/20 modules which are manufactured by Allen-Bradley/Rockwell Automation. This processor control module provides control functions, timing, and interfacing facilities with other processor modules. It is unique to the PLC-2/20 processor. The 1772-LI Processor Control Module has a “PROCESSOR FAULT” indicator which helps to identify the malfunctions in the processor. This indicator can be used to check whether the logic controlling of the processor scan function is working properly without any faults.

The 1772-LI Processor Control Module is located in the middle plastic slot of the processor and that slot is the second slot from the right. It is linked to the memory module to transmit data between 2 modules. The memory module of the processor must be ordered separately. The indicator on this control module is normally off and it illuminates only if a fault has occurred in the controller. This fault usually needs to be corrected by replacing the whole module. The indicator can be seen through the window on the front panel cover and it is labeled as “PROC FAULT” indicator on the window. When replacing the 1772-LI Processor Control Module, make sure to turn mode select switch to the "PROG" position. After the replacement, monitor the diagnostic indicators to assure proper operations. There is a front panel that attaches the processor control module securely to the processor chassis with two thumbscrews. One screw is on the top and the other one is on the bottom of the module.