Commonly Encountered Blocks

BOOL is a Boolean signal, INT is an integer, REAL is a floating point number, ANY is any form of signal
Up-counter counts the number of rising edges at input CU. PV defines the maximum value of the counter. Each new rising edge at CU increments CV by 1. Output Q occurs after set count. R is the reset.
Down-counter counts down the number of rising edges at input CU. PV defines the starting value of the counter. Each new rising edge at CU decrements CV by 1. Output Q occurs when count reaches zero.
Up-down counter. It can be used to count up on one input and down on the other.
On-delay timer. When input IN goes true, the elapsed time at about ET starts to increase and when it reaches the set time, specified by input PT, the output Q goes true.
Off-delay timer. When input IN goes true, the output Q follows and remains true for the set time after which the input Q goes false.
Pulse timer. When input IN goes true, output Q follows and remains true for the pulse duration specified by input PT.

Operators

(…) Parenthesized (bracketed) expression

Function(…) List of parameters of a function

** Raising to a power

−, NOT Negation, Boolean NOT

*, /, MOD Multiplication, division, modulus operation

+, − Addition, subtraction

<, >, <=, >= Less than, greater than, less than or equal to, greater than or equal to

=, <> Equality, inequality

AND, & Boolean AND

XOR Boolean XOR

OR Boolean OR

Conditional and Iteration Statements

IF … THEN … ELSE is used when selected statements are to be executed when certain conditions occur.

The FOR … DO iteration statement allows a set of statements to be repeated, depending on the value of the iteration integer variable.

The WHILE … DO iteration statement allows one or more statements to be executed while a particular Boolean expression remains true.

The REPEAT … UNTIL iteration statement allows one or more statements to be executed and repeated while a particular Boolean expression remains true.