How does an AND function differ from an OR function in ladder logic?

How does an AND function differ from an OR function in ladder logic?

• A. OR requires any input to be true.
• B. AND results in true if any input is true.
• C. They both require all inputs to be true.
• D. AND requires all true; OR requires any true.

Answer: (D)

In ladder logic, how inputs combine to energize an output is determined by how you place the contacts on a rung. An AND relationship is created when the input contacts are placed in series. The coil will energize only if every contact in that series path is closed (true); if any one input is false, the path opens and the coil stays de-energized. An OR relationship is created when the input contacts are placed in parallel. The coil will energize if any one of the parallel paths is completed—i.e., if any input contact closes (true). In short, AND requires all conditions to be true, while OR requires at least one to be true.

In ladder logic, how inputs combine to energize an output is determined by how you place the contacts on a rung. An AND relationship is created when the input contacts are placed in series. The coil will energize only if every contact in that series path is closed (true); if any one input is false, the path opens and the coil stays de-energized. An OR relationship is created when the input contacts are placed in parallel. The coil will energize if any one of the parallel paths is completed—i.e., if any input contact closes (true). In short, AND requires all conditions to be true, while OR requires at least one to be true.