Sierra Wireless AirLink RV50 Series User Manual page 305

Rev 1 Dec. 17
Step 1—Coefficient and Offset
Before you configure ACEmanager, you need to locate or calculate the coefficient
and the offset values.
Consult the user documentation for the equipment you want to monitor. It should
provide you with the coefficient to convert volts to the appropriate unit of
measurement and the offset value (the difference between the equivalent value
for 0 volts and 0), or provide information on equivalent values for voltage readings
from which you can calculate the coefficient and offset. (If this information is not
available in the user documentation, contact the manufacturer.)
For example, if the equipment monitors temperature, and has a scale from 0 volts
to 30 volts, the equipment specifications should provide information similar to the
following:
0 V is equivalent to - 20°C
30 V is equivalent to 100°C
This is expressed algebraically as follows:

a 0V + b = – 20 C

a 30V + b = 100C
where:
a = coefficient
b = offset
For this example, you can calculate a as follows:
    
a 30V + b – a 0V + b

a 30V = 120V
a = 4
To calculate b, substitute a into the first equation above:

4 0V + b = – 20
b = – 20
Step 2—Configure ACEmanager
For each of the analog inputs you want to configure:
1. In ACEmanager, go to I/O > Configuration.
2. Enter the values for the coefficient and offset. (In this example, the coefficient
is 4 and the offset is -20.)
3. Enter the desired unit of measurement. (In this example, the unit of
measurement is C, for degrees Celsius).
ACEmanager shows the value of the transformed analog input as temperature in C.
305
 –  
= 100C – 20
I/O Configuration
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