Smart Average

B48_SMART_AVERAGE

PROGRAM B48_TEST
VAR 
   IN1, IN2, IN3:REAL;
 FB: LIB.CORE.V1_0.B48_SMART_AVERAGE;
END_VAR
 
 FB(IN[1]:=IN1, IN[2]:= IN2);
    O1:= FB.OUT;
END_PROGRAM

LIB\CORE

V1.1

This block is an extension of the AVG block. The AVG block calculates just the arithmetic average, which may cause problems in field deployment: At sites with 3 or 4 room temperature sensors, which are averaged to obtain a room temperature as an input for a room controller, a sensor may get broken and feed a bad value, e.g. of 150 °C. The plain average temperature is useless, while the problem is difficult to detect.

On the other hand, B48 calculates the most probable average temperature by omitting all “out-of-range” values. This is achieved by calculating a median value, M. All input values (X), which are closer to M than the tolerance (tol), are used for average value calculation, while all values outside of the tolerance band are not taken into account.

Output BS gives the sign of the OUT value. If OUT>= 0, then BS=TRUE, else BS=FALSE. The BSN output is a negation of BS.

If the number of sensors is 3, the block is able to detect one false value. If the number of sensors is 5, the block detects up to 2 false values, etc.

Input signals must be enabled by setting the enable variable INENABLED to TRUE (such as inenabled[1]:=true; for the first input IN1).