Hello! Can I get some help with how these ladder diagram would look? I am really new to ladder language.
thank you!

 

 

Most web fora participants will ask you to show your work (with comments), and if there's errors, ask you to explain why you did that way, before providing correction. It's rare to find someone who will do your homework for you. There's nothing preventing that from happening, but I'd be surprised if it happened. We'll see.

 

Read the specification to work out what is required, basically this could be one timer that is self resetting, started by the start button and stopped and reset by the stop button. All the lights can be controlled by comparing the elapsed time of the timer to what is required in the specification.

 

You must see a ladder diagram as a normal hardware wired control cabinet with contacts and relays. The contacts are on the left, the relays on the right.
In a hardware control all lines of contacts controlling the relays happen together and at once.
That is something to keep in your mind very well: all lines in the ladder logic plc program act like they are happening together and at once.
So don't think: it first does rung/line 1, then after that the line below that.
You can make basically anything in ladder logic plc, even state machines.
So: think of it as hardware contacts, relays etc.
Good thing extra in ladder logic plc is that you can also work with numbers, timers etc.

 

That is something to keep in your mind very well: all lines in the ladder logic plc program act like they are happening together and at once.
So don't think: it first does rung/line 1, then after that the line below that.

PLC ladder programs are processed left to right, top to bottom, this needs to be understood by PLC programmers so all intended operations occur. It also needs to be understood when the HMI writes to the PLC, generally this is in between each scan of the program but not with all PLC/HMI systems

 

Here's a suggestion that I give new programmers, and that is to put your outputs in the program and program to them. Otherwise PLC programming can be a bit overwhelming.

And what you've got is a time-based operation with a possible input from start/stop pushbuttons. So...

1) Count up all of the time delays in your process.
2) Create a timer that spans that time range.
3) Look at the accumulated time and turn on/off the lights accordingly.
4) The Stop PB will reset the timer. The Start PB has to be pressed to allow the timer to run. How do you "Seal in" the Start PB?
5) ??
6) Profit!!