x02			c0
-----|   |---------------------(SET)------

      x02			c0
-----| / |---------------------(RST)------

      x01	c0	c2      c1
-----|   |-----|   |--|   |----(SET)------

      x01			c1
-----| / |---------------------(RST)------

      c1			y0
-----|   |---------------------(OUT)------

      c11       x02             c2
-----|   |-----| / |-----------(RST)------

      c2                      ________
-----| / |------------------ |  TMR   |---
                             |  T0    |
                             |  K500  |
                              --------
      T0                       c2
-----|   |--------------------(SET)-------
                           |   T0
                           ---(RST)-------
      c2                       c11
-----|   |--------------------(RST)-------
                    _______
-------------------|  End  |--------------
                    -------
 x01 = Sensor for high water level
 x02 = Sensor for low water level
 c0  = Water level low variable
 c1  = Indicates that the we whant to fill the tank
 c2  = Dump Done
 c11 = Dump valve
 y0  = the actual motor that fills the tank

 Bit Sate  0    0          1    0          1    1
        --x01--x02-     --x01--x02-     --x01--x02-         
	|  |    | |     |  |    | |     |  |    | |
	|''|''''|'|     |  |    | |     |  |    | | 
	|       | |     |'''''''|'|     |       | |
	|	  |     |         |     |'''''''''|
	|_________|     |_________|     |_________|
Process State 1            2               3               
	

The Dump Process waits for the dump valve to open, this is controlled
by the PLC program, it also checks to see that there is some water
to dump. The dump process is set on a timer so as you can see in rung 7
it waits for 50 seconds then stops dumping. Afterwards it sets the Dump Done
variable and resets the Dump Valve in rung 9. In order to make sure that the tank only
fills when we finished dumping we put in the 'dump done switch' in rung 3.