====== Bit rotation ======

{{:en:mervis-ide:35-help:t14.png}}

===== Block name  =====

T14_BIT_ROTATION

===== ST call  =====

<code st-iec>
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
</code>

===== 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 =====

|Input                 |Type       |Description                                                                    |Default value          |
|BX                    |BOOL       |Rising edge input: the vector rotates one position forward at the rising edge  |False                  |
|BXF                   |BOOL       |Falling edge input: the vector rotates one position forward at the falling edge|False                  |
|INI                   |MULTIIOBOOL|Initial bit pattern of the outputs                                             |[True, False,...,False]|
|LIST OF ENABLED       |MULTIIOINT |Field of output numbers which take part in the rotation                        |[1,0,...,0]            |
|NUM OF ENABLED OUTPUTS|INT        |Number of items that take part in the rotation                                 |1                      |

===== Outputs =====

|Input|Type       |Description                                          |
|OUT  |MULTIIOBOOL|Output rotated vector                                |
|SHIFT|INT        |Indication on how many position the vector is rotated|

===== 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.\\