Documentation

Bit Rotation (T14)

Block name

T14_BIT_ROTATION

ST call

PROGRAM TEST14
	VAR 
		INT1,INT2,INT3,INT4: INT;
		BOOL1,BOOL2,BOOL3,BOOL4,BOOL5,BOOL6,BOOL7,BOOL8: BOOL;
		FB: LIB.HVAC.V1_0.T14_BIT_ROTATION;
	END_VAR
	FB.INI[1]:=BOOL3;
	FB.INI[2]:=BOOL4;
	FB.INI[3]:=BOOL5;
	FB.LISTOFENABLED[1]:=INT2;
	FB.LISTOFENABLED[2]:=INT3;
	FB.LISTOFENABLED[3]:=INT4;
	FB(BX:= BOOL1, BXF:= BOOL2, NUMOFENABLEDOUTPUTS:= INT1);
	BOOL6:=FB.OUT[1];
	BOOL7:=FB.OUT[2];
	BOOL8:=FB.OUT[3];
END_PROGRAM

Library

LIB\HVAC

Version

V1.0

Description

Bit rotation shifts and rotates bits in a vector, based on rising or falling edges on the inputs.

Inputs

Outputs

Function

Note: The function block uses own library types: multiiobool and multiioint, which are arrays (array [1...16]) of boolean and integer values respectively. To convert it to individual binary / integer values, use the helper_multiinbool and helper_multioutbool functions, which decompose the array to a set of binary or integer values.

The INI variable must contain the initial pattern, typically “1 of n”, “2 of n” etc., e.g. [1, 1, 0, 0, 0, 0, 0, 0]. When rotating, the pattern moves "forward", so after the first pulse the vector reads [0, 1, 1, 0, 0, 0, 0, 0], and the SHIFT variable is 1, after the second pulse [0, 0, 1, 1, 0, 0, 0, 0], and SHIFT = 2 etc. After the number of pulses equal to NUM OF ENABLED OUTPUTS the vector is back in the initial state, and SHIFT = 0.

In the NUM OF ENABLED OUTPUTS variable the number of inputs to take part in the rotation is specified; with maximum of 16.

The variable ListOfEnabled is an array with output numbers that take part in the rotation. For example, for the first 8 outputs the vector reads [1, 2, 3, 4, 5, 6, 7, 8]. (Typical usage is  n outputs in a row. If five outputs are part of the rotation, namely 1, 3, 4, 5, and 7, the vector reads [1, 3, 4, 5, 7] and NUM OF ENABLED OUTPUTS is equal to 5.

The variables above can be used if some of the outputs shall be excluded from the rotation pattern, e.g. because of boiler failure.

Application example

The block is used as a signal source for rotation of boilers, cyclical switching of pumps, multi-stage electrical heaters, etc. to load all elements in a similar way in the long term.