What timer should be used to keep track of how long a machine is in cycle?

To keep track of how long a machine is in cycle, the best choice is to use a Retentive Timer On (RTO). The primary function of an RTO timer is to accumulate time as long as the input condition is true, and it retains the accumulated value even when the input condition goes false. This feature is crucial for tracking the duration of a machine's operational cycle because it allows the timer to maintain its count across cycles.

In practical terms, when the machine is in cycle, the RTO will continually count the elapsed time. If the machine stops or goes out of cycle, the timer will not reset; instead, it will hold the last value until the machine resumes operation, providing an accurate total time the machine has been in its active cycle over multiple operations. This can be particularly important for maintenance scheduling, performance tracking, and efficiency analysis.

Other timers, such as the Timing Off (TOF), Timing On (TON), and Count Down (CTD) do not retain their accumulated values once the input condition changes, making them unsuitable for the requirement of tracking the total time a machine is in cycle over multiple cycles.