In the previous section, we configured the timer “T4:1” to time for 20 seconds after the Ball Mill motor starts. If the motor stops for any reason, we will need to determine if the motor has run for the 20-second time period.
A TON timer is reset when the input logic to the timer is false, so if the motor stops, I will lose the accumulated time and the “Done” bit if it is has been set.
A Retentive Timer On, or RTO, will retain its timer memory even if the input logic is false.
So, Right-click on the TON instruction label and select “Change Instruction Type” from the menu. Type in RTO and the instruction is updated, preserving the previously configured values.