From the course: Learning PLC Ladder Logic: 1 The Basics

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Counter and timer case study

Counter and timer case study

- [Instructor] So let's take an example where we use both timers and counters. Let's design a system where a parking lot has 10 spots. Whenever a car comes in, a sensor detects a car, and the door opens for three seconds. The three seconds are used for demonstration purposes. In real life, three seconds is really short to keep the door open. So let's keep it for three seconds for programming purposes. A green light is showing that there are some spots left in the parking lot, and a red light, that's showing there is no spots left when the parking is full. The first part in any problem, let's try to identify the inputs and outputs of the system, and I mean the physical devices. So the car sensor is an input to the system. The parking lot door, the green light, and the red light are output to the system. The first thing is that once the car comes in, detected by the sensor, the door opens. So we are going to use an XIC instruction for the car sensor, and for the door, we use it as an…

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