Signal Reader Trigger Expressions

Trigger conditions are expressions evaluated by the Signal Signal reader module to control when recorders are started and stopped and when measurement set-up switches are performed. Trigger conditions are boolean expressions, evaluated to either true or false. A number of operators can be combined to for the trigger expression. The allowed operators in trigger expressions are shown in the table below.

=	Tests for equality. Syntax: expression = expression
!=	Tests for inequality. Syntax: expression != expression
<	Tests for left side of expression being less than right side. Syntax: expression < expression
>	Tests for left side of expression being greater than right side. Syntax: expression > expression
<=	Tests for left side of expression being less or equal to right side. Syntax: expression <= expression
>=	Tests for left side of expression being greater or equal to right side. Syntax: expression >= expression
AND	Logical conjunction between left and right side boolean expressions. Syntax: boolean expression AND boolean expression
OR	Logical disjunction between left and right side boolean expressions. Syntax: boolean expression OR boolean expression
CHANGE	True when the specified signal changes value by at least the specified amount. Syntax: CHANGE(Signal, amount)
CHANGE_UP	True when the specified signal increases its value with the specified amount. Syntax: CHANGE_UP(Signal, amount)
CHANGE_DOWN	True when the specified signal increases its value with the specified amount. Syntax: CHANGE_UP(Signal, amount)
CHANGE_FROM_TO	True when the specified signal changes from the specified value to the other specified value: Syntax: CHANGE_FROM_TO(Signal, value, value)