At Land Rover's factory in Solihull, England, truck bodies queue for the paint shop on conveyors arranged in parallel lanes. Each lane has 25 sections. When a body arrives at a lane, it passes automatically from one section to the next, until it reaches the conveyor for the paint shop. If a section is occupied, the body stays put until the one in front moves on. Sensors in each section keep the system running smoothly.
A conventional control system for this project would consist of a large control panel housing a PLC with I/O racks; starters for each motor; cables for the sensors; electrical distribution and protection equipment; and control buttons, indicator lights and other gear. In addition, the power cables for each motor would have to be wired through a load-break switch.