In this lesson, I'm going to write a PLC program for a vehicle barrier at the parking entrance using a count up and down instruction and also two comparator instructions. What I need the vehicle barrier to do for me is, when the number of vehicles within the parking lot is equal to 500, it should block the parking entrance and when the number of vehicles is less than 495, the barrier should open.
To count the number of vehicles entering and exiting the parking lot, I've used two separate sensors.
When the parking entrance is blocked by the barrier, a signal lamp will be turned on to let the drivers know that the parking lot capacity is full.
In the previous lesson I wrote a PLC program to control the vehicle barrier in a parking lot entrance and also counting the number of the vehicles within the parking lot.
In this lesson I'm going to write a short piece of code for turning on the signal lamp when the parking lot capacity is full...
In some projects you need a PLC output to be energized when a group of PLC inputs are all true at the same time. To write such a PLC program there are two ways:
1. Writing the PLC program using what I call the "bit logic" approach
2. Writing the PLC program Using the comparator operations
In t...
As you know, the maximum amount of time that you can use on S7 or SIMATIC timers for timing is 2 hours 46 seconds. If you need larger timing values, one of the options might be using the IEC timers.
If you're not interested in using IEC timers, the other option is to build your own customized t...
