Example 1

This script reads the value of the given input Data Item, make some mathematical operations ( sqrt, round ), and than compare it with the max value saved as global variable. If this max value is exceeded, a warning text is shown, and new max value is set.

First, new global variable called g_max is created, to store the max value:

Second, a new Script Item called Watch is created. Than add new JS variable, set name to input, and set Item Path to the data item, that we want to watch.

And the script :

// watch given input, modify it, and if it is higher than

// max value, show message, and set new max value

function OnItemRead_Watch(input)

{

var RetVal;

// examples of mathematical operations

var v = Math.sqrt(input);

var r = Math.round(v);

// compare with max value

if ( r > g_max )

{

// if max value exceeded, show warning, and set new max

RetVal = "MAX VALUE EXCEEDED";

g_max = r;

} else {

// else everything OK

RetVal = "VALUE IN RANGE";

}

return RetVal;

}