Anadex Labs Pty Ltd    
  Anadex Labs
  Easy water tank level display and control
 
     
         
 
   

 

C-Bus Scaling Calculator
For the AN420-5 water level sensor

 
  One of the steps that needs to be done after installing a 4-20mA sensor (AN420-5), is to scale the readings from the sensor (raw value) to a "Real World" value that is meaningful to people. In this case, we are dealing with water volume or depth. This means that the output from the AN420 water level sensor needs to be scaled to a real world value such as:
  • Liters or gallons
  • Percentage
  • Water depth in meter or feet

Once this scaling has been applied to the raw sensor data, the scaled water level data may be presented to the user in text or graphical format.
 
The purpose of this calculator is to provide you with the appropriate scaling factors (multiplier and offset) that may be used to configure a channel on the C-Bus General Input Unit. (Note that this scaling may be used for other applications as well.)

Enter the two input values and press "Calculate".
A new page will open and will contain the following information (make a note of these readings):

  • The AN420-5 current reading in mA (raw value) when the tank is full
  • The scaling multiplier
  • the scaling offset (note that is value will be negative)

 

 
 
 
Scaling Calculator
 		    
Enter in meters the depth of water in the tank when it is full. Example 2.2    
Enter the real world value that needs to be displayed when the tank is full (Liters,%,m,ft)
Example:
If you want % then enter 100 here.
If you want to show liters and your tank holds 80,000L the enter 80,000.
If you want kilolitres then for the example above you will enter 80.		    
     

 		  
 
(Optional) Scaling check calculator (What is this ?)
 		    
Enter your multiplier here    
Enter your offset here (Remember the negative sign)    
Enter any depth for the tank in meters
(This value should be <= the maximum depth of the tank used to calculate the scaling factors)		    
 

 
  The scaling check calculator will use the multiplier and offset that you supply (this may have been obtained from the Scaling calculator), to generate the "Real world" value and the AN420-5 current reading in mA for any given tank depth.

For example: You calculated, using the Scaling Calculator, that the multiplier and offset for a tank that has a depth of 2.2m and holds 10,000 liters, is 1136.36 and -4545.45 respectively.
If you enter these values in the scaling check calculator and enter a tank depth of 2.2m, you will get 10,000.
If you changed the current tank depth to say 1.1m, the tank volume becomes 5,000.

The formula used is of the type y =mx+c.
Where y = the real world value, m is the multiplier, x is the current depth and c is the offset.		  
     
 
  21/09/08     Copyright Anadex Labs Pty Ltd 2006