=====Showing a custom message box in older software=====

In [[plc:plc_gas_cutting_implementation|previous article]] we showed how to implement oxyfuel gas cutting procedure. Preheat process in gas cutting can last 30-120 seconds. It is convenient to have on screen message that shows preheat progress. Let's add message box with preheat progress countdown for gas cutting.

Global variables 9100-9163 are reserved to show/hide enumerated Popup message box.
Writing "1" to register (9100+N) will show Message Box #N on the main screen. Writing "0" will hide the Message Box.

Content for message box #0...#63 defined in cnc-variables.xml configuraton file by item **cnc-popup-message-0** ... **cnc-popup-message-15** 

<code xml>
<value name="cnc-popup-message-0" 
  header="Preheat Countdown" footer="sec" message="%d" 
  headerHeight="60" footerHeight="30" width="300" height="150"
  fontSize="60" headerFontSize="30" footerFontSize="20" 
  timeout="5" dest="cnc-gvariable-99" K="0.001">0</value>
</code>

Message box contains 3 lines. Lines defined by attributes **header** (top line), **message** (middle line), **footer** (bottom line). Font size for each line defines by attributes **headerFontSize**, **fontSize** and **footerFontSize**

Line height for each line defined by attributes **headerHeight**, **height** and **footerHeight**.

Attributes **width** and **height** define message box width and height in pixels.
Popup Messagebox will be automatically hidden if variable value was not changed longer than time defined in **timeout** attribute.

Parameter value can be printed in Message Box. To print a value - 
  * Message attribute should contain C-style contains format line (ie "%d", "%7.3f")
  * Attribute **dest** should define variable number 
  * Attribute **K** defines scale ratio.

For example if 
  * message="%d"
  * dest="cnc-gvariable-99" 
  * K="0.001"

Variable #99 value multiplied by K-ratio will be printed: if variable value is 95000, value **95** will be shown.

{{plc:mycnc-eco-popup-message-01.png}}

Source code to show Message Popup is 
<code c>
  gvarset(9100,1);  //show the Message Box
  portset(OUTPUT_OXY_HEAT_HI); //turn ON preheat Valve
  timer=time_preheat;
  break_heating=1;	//Set Heating variable. 
  //if the value will be clearen outside of PLC, abort Preheat procedure
  do {
    timer--;
    if (portget(6)!=0)	//if start key is pressed - start piercing
      {
	timer=0;	//exit from heating
      };		
    if (break_heating==0)   //if start key is pressed - start piercing
      {
	timer=0;	    //exit from heating
      };		
    if ((timer&0xff)==0)
      {
	gvarset(99,timer); //update Countdown value every 256msec
      };
   }while(timer>0);        //Preheat loop

  gvarset(9100,0);         //hide Message Box
</code>