Generac Power Systems H-100 사용자 설명서

 38

The User Configurable Analog Inputs have several 
parameters that affect the value interpreted from 
the A/D reading. In general, the following equation 
determines the final User Configurable Analog Input 
result:

Result =  Scale (Function (Calibrate (Raw A/D read-

ing)))

For functions that require 4 coefficients for a polyno-
mial, the calibration factor has to be incorporated in 
the polynomial coefficients. In this case, the follow-
ing equation determines the final User Configurable 
Analog Input result:

Result = Scale (Function (Raw A/D reading))

The RMS Analog Inputs have a calibration parameter 
and a scaling parameter that affect the value inter-
preted from the A/D reading. The following equation 
determines the final RMS Analog Input result:

Result =  Scale (Calibrate (RMS Function (Raw A/D 

reading)))

Although the calibration and scaling adjustments 
exist for the remaining Analog Inputs (i.e. derived 
channels), it is unlikely they will be used. The 
remaining Analog Inputs are derived from other ana-
log inputs that have already been adjusted. If further 
adjustment is needed, then the following equation 
determines the final Analog Input result:

Result =  Scale (Calibrate (RMS Function (Raw A/D 

reading)))

These derived inputs have more complex interactions 
with the hardware, so care should be taken if adjust-
ments are used.

The conversion functions are described below. One of 
these functions is a 16 bit floating point polynomial 
- GEN_FP_POLY. This function should only be used 
as an extreme last resort as it is processor time inten-
sive. The other integer polynomial functions should 
be sufficient for converting the A/D input data.

The coefficients for the conversion functions need to 
be adjusted for working in the A/D counts realm as 
opposed to the voltage realm. Multiply A/D reading 
voltage by 1023/5 to convert to A/D reading counts. 
Also, the coefficient scaling is in powers of 2 to 
expedite processing of math operations using shifts 
instead of multiply and divide. The following types 
of Analog Input functions are implemented in the 
firmware.

THERMISTOR:

PRESSURE:

POLY_3RD:

Third order polynomial with 4 coefficients and a scal-
ing factor

 X 

= 

raw_analog

 

(AX3 + BX2 + CX + D) * S

Where:

A, B, C, D are polynomial coefficients
S is the scaling factor
 

Coefficient 3  = A * 10243

 

Coefficient 2  = B * 10242

 

Coefficient 1  = C * 1024

 Calibration 

= 

D

 

Scaling 

= S * 1024

POLY_2ND:

Second order polynomial with 3 coefficients, a scal-
ing factor, and a calibration factor

 

X = M * raw_analog

 

(AX2 + BX + C) * S

Where:

 

M is the calibration factor

 

A, B, C are polynomial coefficients

 

S is the scaling factor

 

Calibration  = M * 1024

 

Coefficient 3  = A * 10242

 

Coefficient 2  = B * 1024

 

Coefficient 1  = C

 

Scaling 

= S * 1024

LINEAR:

POLY_1ST:

First order polynomial with 2 coefficients, a scaling 
factor, and a calibration factor

 

X = M * raw_analog

 

(AX + B) * S

Where:

 

M is the calibration factor

 

A, B are polynomial coefficients

 

S is the scaling factor

 

Calibration  = M * 1024

 

Coefficient 2  = A * 1024

 

Coefficient 1  = B

 

Scaling 

= S * 1024

POLY_1ST_N1:

First order polynomial with 3 coefficients, a scaling 
factor, and a calibration factor

 

X = M * raw_analog

 

(A + BX + CX-1) * S