Description

Function description

This function block enables PID control of servo motors with or without positional feedback. The function block can be switched to be the controller (PIDFF, PI_B) so that the digital outputs become the two logical outputs RAISE and LOWER.

If the function block uses positional feedback, then positioning controlling of the actuator will be performed. If positional feedback is not being used, the controller and the SERVO function block operate a continuous static control together.

and can be configured as additional parameters.

Representation in FBD

Representation:

Representation in LD

Representation:

Representation in IL

Representation:

CAL SERVO_Instance (SEN:=New_INPD_Or_IN_ValueFlag, 
    IN:=ControllerOutputOUT, INPD:=VariationOf_IN, 
    MA_I:=OperatingMode, RCPY:=PositionalCopy, 
    RST:=BlockReinitialization, 
    R_STOP:=ReachedEndstopOfRAISE, 
    L_STOP:=ReachedEndstopOfLOWER, PARA:=Parameters, 
    RAISE=>TravelDirectionOfRAISE, 
    LOWER=>TravelDirectionOfLOWER, STATUS=>StatusWord)

Representation in ST

Representation:

SERVO_Instance (SEN:=New_INPD_Or_IN_ValueFlag, 
    IN:=ControllerOutputOUT, INPD:=VariationOf_IN, 
    MA_I:=OperatingMode, RCPY:=PositionalCopy, 
    RST:=BlockReinitialization, 
    R_STOP:=ReachedEndstopOfRAISE, 
    L_STOP:=ReachedEndstopOfLOWER, PARA:=Parameters, 
    RAISE=>TravelDirectionOfRAISE, 
    LOWER=>TravelDirectionOfLOWER, STATUS=>StatusWord) ;

Parameter description SERVO

Input parameter description:

Parameter	Data type	Meaning
SEN	BOOL	"1" : Including a new value at the INPD or IN inputs "0" : no inclusion of the new values of INPD or IN
IN	REAL	Control output OUT (0 to 100%)
INPD	REAL	Output alteration OUTD of the controller (-100% to 100%)
MA_I	BOOL	Control operating mode (Output MA_O) "1" : Automatic mode "0" : Manual or tracking mode
RCPY	REAL	Positional feedback (0 to 100%)
RST	BOOL	"1" : Reinitialization of the function block (resetting outputs and the internal function block status)
R_STOP	BOOL	End position RAISE reached
L_STOP	BOOL	End position LOWER reached
PARA	Para_SERVO	Parameter

Output parameter description:

Parameter	Data type	Meaning
RAISE	BOOL	Logical output in the direction RAISE
LOWER	BOOL	Logical output in the direction LOWER
STATUS	WORD	Status word

Parameter description Para_SERVO

Data structure description

Element	Data type	Meaning
en_rcpy	BOOL	"1" : Function with positional feedback (including RCPY)
rcpy_rev	BOOL	"1" : Inversion of RCPY "0" : no inversion of RCPY
t_motor	TIME	Actuator opening time
t_mini	TIME	Minimum impulse length

REAL

The REAL type is encoded in a 32 bit format.

The possible value ranges are shown in the figure below:

When a result is:

between -1,175494e-38 and 1,175494e-38, it is considered to be a DEN;
less than -3.402824e+38, the symbol -INF (for - infinity) is displayed;
greater than +3.402824e+38, the symbol INF (for + infinity) is displayed;
undefined (square root of a negative number), the symbolNAN is displayed.

NOTE: The IEC 559 standard defines two classes of NAN: the silent NAN (QNAN) and the signaling NAN (SNAN). A QNAN is a NAN with a most significant fraction bit while an SNAN is a NAN without a most significant fraction bit (bit number 22). QNANs can be propagated via most arithmetic operations without throwing an exception. As for SNANs, they generally indicate n invalid operation when they are used as operands in arithmetic operations (see %SW17 and %S18).

NOTE: When a DEN (non-standardized number) is used as an operand, the result is not significant.

Base	Lower limit	Upper limit
Hexadecimal	16#0	16#FFFF
Octal	8#0	8#177777
Binary	2#0	2#1111111111111111

Data	Representation in one of the bases
0000000011010011	16#D3
1010101010101010	8#125252
0000000011010011	2#11010011