... loops and optional programming commands. The processor consists of themicroprocessor, system memory, serial communication ports for printer, PLC LAN link and external programming device and, ... fundamentalunderstanding of the various types of PLCs available, the advantages and disadvantagesof each, and the way in which a PLC executes a program. The open frame, shoebox, and modular PLCs are ... first PLCs were developed and why they were better than the existingcontrol methods. ” the difference between the open frame, shoebox, and modular PLC configurations, and the advantages and disadvantages...