![simplest ladder logic program simplest ladder logic program](https://secureservercdn.net/198.71.233.179/t53.84d.myftpupload.com/wp-content/uploads/2017/08/LL208_CycStart1-2.jpg)
An easy way to remember this is AND works like multiplication.
![simplest ladder logic program simplest ladder logic program](https://i1.wp.com/www.electroniclinic.com/wp-content/uploads/2019/09/plc-based-load-management-circuit-diagram.png)
The truth table below shows that the output is only turned on when all the inputs are true (1). The AND gate is associated with the following symbol that can have any number of inputs but only one output. The ladder logic equivalent for a NOT function looks like a normal contact but with a slash through it. Shown below is a truth table (it doesn't lie) showing all possible inputs and the resulting logical output. So an input of 1 will come out as a 0 and visa versa. It's sole function in life is to invert of flip the logic state. The simplest of all logic functions is the NOT gate. These functions are also called gates as they act like gate keepers for different logic.
SIMPLEST LADDER LOGIC PROGRAM SERIES
A series of graphical objects have been used for years to represent these logic elements and they can be easily converted to a common ladder logic equivalent. It would be nice to program like this but computers like to be a little bit more structured.
SIMPLEST LADDER LOGIC PROGRAM FULL
If the tank is full OR the button is pressed AND there are no alarms then start the process.Relying on a signal to turn on when a wire has fallen off long ago may cause an awkward moment when we truly have to stop the machine in an emergency.) In either case we want to check this for safety reasons. (This is an example of a failsafe operation as the emergency stop button could be pressed or the wire has been disconnected. If the process is done OR the emergency stop button signal is NOT on then turn off the motor.When the button is pressed AND the door is closed then turn on the motor.Let's turn again to some simple statements but this time using automation examples. This is abitrary though as it may make more sense to use what is called failsafe logic and have an ON bit as a FALSE condition. Typically having a bit ON represents a TRUE condition while OFF is FALSE. In the PLC it all boils down to our now familiar binary system of a 1 or a 0. In the world of automation these types of TRUE or FALSE conditions come down to a device being ON or OFF, CLOSED or OPEN, PRESENT or ABSENT, 24 VOLTS or 0 VOLTS. Now we could get more complex but all that we'd be doing is using these simple building blocks. You'll notice that they all involve three types of comparisions: AND, OR and NOT. Now these are pretty simple decisions especially if you're a ten year old boy. If Mom comes out AND orders me inside OR it get's dark then I'll stop playing.It's 6 o'clock AND I'm NOT hungry therefore I'm going to keep playing.If Tommy OR Bob want to play basketball then I'll play too.All though I've always found computers to be quite a bit more logical then human beings.įor an example of how we use logic in everyday life consider these statements:
![simplest ladder logic program simplest ladder logic program](https://www.ele.uva.es/~jesman/BigSeti/ftp/Cajon_Desastre/PLCs/mikroelektronika/01-3.gif)
We gather information (input) and based on that we make choices that determine our output. What is true for us is also true of PLCs.