In PLC programming, what does the DN bit typically indicate?

The DN bit in PLC programming stands for "Done" and is used to indicate that a timer has completed its countdown. When a timer is set up in a PLC program, the DN bit is typically set to true or high when the timer reaches its preset time. This functionality is crucial when designing control systems that rely on timed operations.

Understanding the role of the DN bit is important for programming efficient and accurate control logic in PLC systems. It allows other parts of the program to take action based on whether the timer has finished counting. For example, after confirming that the DN bit is set, you can trigger subsequent processes or output devices, ensuring that the system operates in a coordinated manner based on time-dependent events.

In the context of the options provided, this clarification distinguishes the DN bit's role from other states or conditions of the timer, such as its active state, reset state, or paused state, which serve different purposes in a control scheme.