The many similarities between the ladder diagrams used to program PLCs and the relay ladder logic formerly used to control industrial systems eased the transition from hardwired relay systems to PLC .

The solution proposed involves a modular approach, combining ladder logic for easy troubleshooting with function blocks written in preferred languages underneath, with a focus on creating modular code ...

Fig. 2. Ladder logic uses memory locations rather than hard-wired logic. For the program shown in Fig. 2, we took the relay logic’s ladder diagram from Fig. 1 and duplicated it with ladder logic — no ...