Example 2

Here we wil show :

how to save last 5 values of some variable

how to view these stored values to user

statistical processing of these values, computing of average value

First, we need to create global array of size 5, we will call it g_history:

This array should be the same type as the watched item, in our case it is LONG. To save the values of this item into g_history array, the following script is used:

function OnItemRead_MartinPC_enterprises_enterprises_15_0_0_4(enterprises_15_0_0_4)

{

// save last 5 inputs into g_history

var i;

// shift left values in g_history

for ( i=0; i<4; i++ )

{

g_history[i] = g_history[i+1];

}

// set new top value

g_history[4] = enterprises_15_0_0_4;

return enterprises_15_0_0_4;

}

function OnItemWrite_MartinPC_enterprises_enterprises_15_0_0_4(enterprises_15_0_0_4)

{

return enterprises_15_0_0_4;

}

The script to view these 5 values :

// function shows last 5 values of some input

// these values are saved in g_history global array

function OnItemRead_LastValues()

{

var RetVal = "";

var i;

// show all values in []

for ( i=0; i<5; i++ )

{

RetVal += "[" + g_history[i] + "]";

}

return RetVal;

}

And the computing of average value :

// compute the average of values in g_history

function OnItemRead_Average()

{

var RetVal = "";

var avg=0.0;

var i=0;

// compute sum of the values

for ( i=0; i<5; i++ )

{

avg += g_history[i];

}

// divide the sum with the number of elements

avg /= 5;

RetVal = "Average = " + avg;

return RetVal;

}