Depends on the model the early 0 models could not display it, the parameter to turn it on in the later ones is P0060 bit #2 set to 1.
They are commonly stored in eprom, the ladder is written in a display format based on Boolean logic.
All the M,S,T codes are decifered in the ladder logic.
There is a bus called the BMI, Basic Machine Interface which has registers, Gxxxx and Fxxxx, to allow the CNC side to communicate back and forth with the ladder (PMC).
Al.
CNC, Mechatronics Integration and Custom Machine Design
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.