The use of programmable controllers eliminates the need for ___.

The use of programmable controllers eliminates the need for ___.

• A. external timing relays
• B. power supplies
• C. inputs
• D. outputs

Answer: (A)

Programmable controllers handle timing inside the controller itself, using built-in timer instructions. This lets you replace external timing relays that used to delay signals or create timed outputs. In ladder logic you can implement on-delay, off-delay, and pulse timers directly in the PLC, driven by its internal clock and scan cycle. The result is a simpler, more reliable control circuit with fewer components, since external timing relays aren’t needed. You still need a power supply and proper input/output modules to run and monitor the system, but the external timing relay is no longer required.

Programmable controllers handle timing inside the controller itself, using built-in timer instructions. This lets you replace external timing relays that used to delay signals or create timed outputs. In ladder logic you can implement on-delay, off-delay, and pulse timers directly in the PLC, driven by its internal clock and scan cycle. The result is a simpler, more reliable control circuit with fewer components, since external timing relays aren’t needed. You still need a power supply and proper input/output modules to run and monitor the system, but the external timing relay is no longer required.