Attention

IronPLC supports IEC 61131-3 Structured Text excluding I/O mapping.

Contacts

Contacts are input elements in ladder diagrams that read the state of a boolean variable. Power flows through a contact when its condition is met.

IEC 61131-3

Section 3.2

Support

Not yet supported

Contact Types

Type

Symbol

Description

Normally open

--| |--

Passes power when the associated variable is TRUE

Normally closed

--|/|--

Passes power when the associated variable is FALSE

Positive transition

--|P|--

Passes power on rising edge (FALSE to TRUE)

Negative transition

--|N|--

Passes power on falling edge (TRUE to FALSE)

Description

A normally open contact is equivalent to reading a boolean variable directly. A normally closed contact is equivalent to applying NOT to the variable.

See Also