SMP Gateway User Manual • 173
IsTrigger( point ) Evaluates to TRUE if the specified point causes the expression
to be reevaluated.
QualityOf( point ) Evaluates to TRUE if the value of the specified data point is
valid.
TimestampOf( point ) Returns the timestamp of a point, as a number of milliseconds
that have elapsed since an internal reference date and time. Use
this function for the sole purpose of comparing timestamps that
were obtained via a previous call to the TimestampOf()
function.
BAD_QUALITY Sets the quality of a data point to BAD, which means that the
value of the data point cannot be assumed as valid.
17.1.4.6 Generators
You can use the following built-in generators in expressions. Generators are used to
mathematically generate input values for data points.
Generator Description
Sine( amplitude, frequency, phase ) Generates an expression of the form: Sine( A, f, P ).
Calculates the value of a sinusoid with an amplitude A, a
frequency f in hertz, and an initial phase P in degrees. P is
optional and if you don't specify it, it will be assigned a value of
0.
Pulse( amplitude, frequency, duty
cycle, delay )
Generates an expression of the form: Pulse( A, f, dc, d ).
Calculates the value of a pulse stream with an amplitude A, a
frequency f in hertz, a duty cycle cd in percent, and a delay of d
milliseconds. d is optional and if you don't specify it, it will be
assigned a value of 0.
Saw( amplitude, frequency, delay ) Generates an expression of the form: Saw( A, f, d ).
Calculates the value of a sawtooth wave with an amplitude A, a
frequency f in hertz, and a delay of d milliseconds. d is optional
and if you don't specify it, it will be assigned a value of 0.
Randn( mean, variance ) Generates an expression of the form: Randn( mean, var ).
Calculates a random value with a normal distribution that has a
mean value of mean and a variance of var.
Rand() Generates an expression of the form: Rand( ).
Calculates a random value with a uniform distribution ranging
between 0.0 and 1.0.
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