• Meant to diagram relay logic
• or PLC logic
  • (which is the same thing, in effect)

Each rung contains the inputs/variables needed to flow current from input (left) to output (right). Pages should have blank rungs to allow for stuff to be added later.

• [?] If this is meant to be digital, why do we make so many pages?

Symbols

As per IEC 61131-3

Contact Symbols

Symbol	Meaning		Symbol	Meaning
	Normally Open Contact			Positive-transition sensing contact
	Normally Closed Contact			Negative-transition sensing contact

Coil Symbols

N.B. Siemens PLCs use Latch/Unlatch in place of Set/Reset

Symbol	Meaning		Symbol	Meaning
	Coil			Negated Coil
	Set latch coil			Reset latch coil
	Positive Transition Sensing Coil			Negative Transtion Sensing Coil