[applied_heat]

The ladder paradigm has its place, as does function block diagrams, as does what the plc vendors call ‘structured text’.

controlling physical processes like oil refineries, power generation, or sawmills is different from most computer programs as are the consequences of bugs or errors so it makes sense that it takes different people with different interests and skills.

[Kim_Bruning]

I can't do the nuances justice here for sure. But to make a long story short:

PLCs replace relay circuits for Industrial Electrical technicians (hence: Ladder). And make no mistake: relay circuits are important, and is something they are very adept at!

However, this doesn't imply that they are automatically able to write or debug regular Python or C code or what have you.

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PS. If you let a PLC programmer at any language, they'll find a way to do ladder logic. Illustrative example (combining some features I've seen in textbooks and IRL, formatting included):

  if Tank_Level_Reached == True and EF132121 == False and Ready_To_Start == True and Finished == False and Belt == Not_Ready and Stage == 5 and Position_Left_Arm == Up :
    move_left = True
    move_right = False

   if Tank_Level_Reached == True and EF132121 == False and Ready_To_Start == True and Finished == False and Belt == Not_Ready and Stage == 5 and Position_Left_Arm == Down:
   move_left = False
   move_right = True

   if Tank_Level_Reached == True and EF132121 == False and Ready_To_Start == False and Finished == False and Belt == Not_Ready and Stage == 5 and (Position_Left_Arm == Down or Position_Left_Arm == Up):
    move_left = False
    move_right = False

etc ...