Essay On Timers

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The use of counters and timers in PLCs has helped increase the efficiency of manufacturing and been of great importance. Timers and counters have been used outside plcs for a long time have shown themselves to be of great help. There use inside plcs has helped reduce space and the many of the complications of hardwiring. First, let’s start out with the Ton timer. Ton timers were first used in plcs in the slc 500s. For all timers, there are three bits. The enabled bit, timer timing bit, and the done bit. On a Ton timer, the enable bit activated when there is a path of true conditions energizing the timer. The timer timing bit is activated when the timer is energized, and the timer is timing up to the preset. Lastly, the done bit energizes …show more content…

What has changed greatly is when the timer timing and down bits energize and de-energize. The timer timing bit for an TOF timer energizes when the timer loses a path of true conditions. This can be useful for if this timer is put in parallel with a load and you want a device to run for a set amount of time after the load has de-energized. With there use the allow for the simplifying of a program and more ease of understanding. Furthermore, the done bit energizes as soon as the timer energizes. When the timers accumulative value reaches its preset the done bit de-energizes opposite of the TON and the RTO. Next, there are counters and their functions. There are two types of counters the count up and the count down. Like timers, they have a done bit. It works exactly the same as it did when used in timers. Unlike timers though counters also have count up and count down bits. When the counter is energized, depending on which counter is being activated, the counter will add or deduct one number from the accumulative value. It will only add one number for each false to true transition. Count up timers can be used to reach a specific amount of material or objects. Using a count down and a count up timer together in a program with the same address is very useful. One counter will count during a certain set of conditions up and the other down with its

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