Description
Original instructions
About us
Function description
The function block creates a velocity limiter with manipulated variable limiting.
The gradient of the input variable IN is limited to a predefinable RATE value. It also limits the output OUT to within OUT_MAX and OUT_MIN. This allows the function block to adjust signals to the technologically limited pace and limits from controlling elements.
NOTE: This function block performs an internal initialization in the first program cycle after a warm start or cold start (e.g. application download or power cycle) of the PLC program.
Due to this, you have to make sure that the function block is invoked in the first program cycle. In case of inkoving the function block in a later program cycle, the internal initialization will not be performed and the ouputs may deliver wrong values.
WARNING
UNEXPECTED OUTPUT BEHAVIOUR
Make sure that the function block is always invoked in the first program cycle.
Failure to follow these instructions can result in death, serious injury, or equipment damage.
EN and ENO can be configured as additional parameters.
Properties
The function block has the following properties:
Representation in FBD
Representation:
Representation in LD
Representation:
Representation in IL
Representation: 
CAL VEL_LIM_Instance (IN:=Input, 
    RATE:=MaximumVelocityLimitation,  
    OUT_MIN:=LowerOutputLimit, OUT_MAX:=UpperOutputLimit, 
    TR_I:=InitializationInput, TR_S:=InitializationType, 
    OUT=>Output, QMIN=>OUT_Reached_OUT_MIN, 
    QMAX=>OUT_Reached_OUT_MAX)
Representation in ST
Representation: 
VEL_LIM_Instance (IN:=Input, 
    RATE:=MaximumVelocityLimitation,  
    OUT_MIN:=LowerOutputLimit, OUT_MAX:=UpperOutputLimit, 
    TR_I:=InitializationInput, TR_S:=InitializationType, 
    OUT=>Output, QMIN=>OUT_Reached_OUT_MIN, 
    QMAX=>OUT_Reached_OUT_MAX) ;
Parameter description
Description of input parameters:
Parameter
Data type
Description
IN
REAL
Input
RATE
REAL
Maximum velocity limiting
OUT_MIN
REAL
Lower limit
OUT_MAX
REAL
Upper limit
TR_I
REAL
Initialization input
TR_S
BOOL
Initialization type
"1" = Operating mode tracking
"0" = Automatic operating mode
Description of output parameters:
Parameter
Data type
Description
OUT
REAL
Output
QMIN
BOOL
"1" = Output OUT has reached lower limit
QMAX
BOOL
"1" = Output OUT has reached upper limit
Runtime error
With OUT_MAX < OUT_MIN an error message appears.
NOTE: For a list of all block error codes and values, see Conditioning.