Signal Reader Trigger Expressions

Trigger conditions are expressions evaluated by the 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 form 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 at least the specified amount. Syntax: CHANGE_UP(Signal, amount)
CHANGE_DOWN	True when the specified signal decreases its value with at least the specified amount. Syntax: CHANGE_DOWN(Signal, amount)
CHANGE_BY	True when the specified signal changes value by exactly the specified amount. Syntax: CHANGE_BY(Signal, amount)
CHANGE_UP_BY	True when the specified signal increases its value by exactly the specified amount. Syntax: CHANGE_UP_BY(Signal, amount)
CHANGE_DOWN_BY	True when the specified signal decreases its value by exactly the specified amount. Syntax: CHANGE_DOWN_BY(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)
TIMER	Effects a delay in seconds from that the specified signal is greater than zero. Syntax: TIMER(signal, time)
EXPR_TIMER	Effects a delay in seconds from that the condition is fulfilled. Syntax: EXPR_TIMER(expression, time)
TIME_COUNTER	Counts the time elapsed while the supplied boolean expression has been true. You can optionally supply an expression resetting the time counter to zero. Syntax: TIME_COUNTER(expression) or TIME_COUNTER(expression, expression)
SAMPLE_COUNTER	Counts the number of samples received while the boolean expression is true. You can optionally supply an expression resetting the time counter to zero. Syntax: SAMPLE_COUNTER(expression) or SAMPLE_COUNTER(expression, expression)
EVERY	Repeatedly becomes true after a time interval, specified in seconds, has elapsed. Syntax: EVERY(time)
MOVAV	Calculates a moving average over the specified signal. Syntax: MOVAV(Signal)
ABS	Calculates the absolute value of the specified expression. Syntax: ABS(expression)
MIN	Calculates the minimum value of two expressions. Syntax: MIN(expression, expression)
MAX	Calculates the maximum value of two expressions. Syntax: MAX(expression, expression)
MEAN	Calculates the mean value of two expressions. Syntax: MEAN(expression, expression)
LOSS_OF_SIGNAL	True when the specified signal disappears for the specified number of seconds. Syntax: LOSS_OF_SIGNAL(Signal, seconds)