Omega Vehicle Security OM-550 manual Data Scaling mX + b calculation

4.14.4 DATA SCALING (mX + b calculation)

The output voltage of a properly matched transducer can be read the but the data will be in "volts" and the user might prefer data in units that reflect the application. Programming the OM-550 to produce data in terms of the actual parameter being measured is called Scaling.

The linear slope-intercept formula (Y = mX + b) makes this possible. Given an input "X", careful choice of m and b can scale the output "Y" to any value, with some restrictions:

∙Some m or b values will produce values too large (or small) to print, although they will be correctly saved to memory for transfer to a PC. Such values will print as "******". Refer to section 4.2 PRINT FORMATTING.

∙The OM-550 can resolve 100 µV (±0.0001 VDC). This means that one A/D converter "count" (the LSB) is worth 0.0001 VDC and the maximum input voltage (±2.0000 VDC) represents ±20,000 A/D converter counts.

∙The m and b values you choose must be within the allowable ranges:

-9.99999 < m < +9.99999 -999999 < b < +999999

The following equations show how to scale data to the actual value of the parameter being measuring. They assume that an increasing transducer output indicates an increasing parameter. (If your system is inversely proportional, just change the sign of the m value). Remember that m and b can be positive or negative.

X1	=	minimum voltage expected at the input
X2	=	maximum voltage expected at the input
Y1	=	minimum parameter value for your application
Y2	=	maximum parameter value for your application
m	=	(Y1-Y2) / (X1-X2) b = Y2 - (m * X2)

OM-550 u34u