The connection of Classicladder is done in your hal file.
There are instructions for setting it up here.
linuxcnc.org/docs/html/ladder/classic-ladder.html
and
linuxcnc.org/docs/html/man/man9/classicladder.9.html
And there is a couple of example simulation configurations using Classicladder that come with Linuxcnc. You can look at those files for some examples.
A couple of quick examples of lines of hal code for connecting some parallel port pins to CL pins.
To send a signal from CL to the parallel port pin #1.
Code:
net cl-out <= classicladder.0.out-00 => parport.0.pin-01-out
And to send a signal from the parallel port pin #10 into CL.
Code:
net cl-in <= paraport.0.pin-10-in => classicladder.0.in-00
A hal novice might look at the above lines and think "Hey you can't connect 2 output pins together", but the parallel port names are a little confusing in that the hal pin named paraport.0.pin-01-out is a hal "input" pin that controls the output from the parallel port.
There are a few more lines of code that have to be added to your hal file to load and configure Classicladder. They are covered in the manual pages linked to above.
