Example 1
Watch and test input variables, using of math functions
Previous  Top  Next


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:

clip0097  

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.

clip0098  

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;  
}  

 


Send feedback on this topic.
Copyright © 2004-2013, SAE - Automation, s.r.o. (Ltd.), All rights reserved.