MC_ReadStatus

MC_ReadStatus 1:

The MC_ReadStatus function block determines the current operating state of an axis and signals it at the function block outputs.

The updated operating state is additionally stored in the Status output data structure and in the Axis.Status axis data structure. This means the operating state only has to be read once at the start of each PLC cycle and can then be accessed via Axis.Status.

The Axis variable (type AXIS_REF) already includes an instance of the function block MC_ReadStatus. This means that the operating state of an axis can be updated at the start of a PLC cycle by calling up Axis.ReadStatus.

Sample:

PROGRAM MAIN
VAR
    Axis1 : AXIS_REF
END_VAR

(* call the read status function *)
Axis1.ReadStatus;

Inputs

VAR_INPUT
    Enable : BOOL; 
END_VAR

Name	Type	Description
Enable	BOOL	If Enable = TRUE, the axis operating state is updated with each call of the function block.

Inputs/outputs

VAR_IN_OUT
    Axis : AXIS_REF;
END_VAR

Name	Type	Description
Axis	AXIS_REF	Axis data structure that unambiguously addresses an axis in the system. Among other parameters it contains the current axis status, including position, velocity or error state.

Outputs

VAR_OUTPUT
    Valid              : BOOL; 
    Busy               : BOOL; 
    Error              : BOOL;
    ErrorId            : UDINT;
    (* motion control statemachine states: *)
    ErrorStop          : BOOL; 
    Disabled           : BOOL; 
    Stopping           : BOOL; 
    StandStill         : BOOL; 
    DiscreteMotion     : BOOL; 
    ContinuousMotion    : BOOL; 
    SynchronizedMotion : BOOL; 
    Homing             : BOOL;
    (* additional status *)
    ConstantVelocity   : BOOL;
    Accelerating       : BOOL;
    Decelerating       : BOOL; 
    (* status data structure *)
    Status             : ST_AxisStatus; 
END_VAR

Name	Type	Description
Valid	BOOL	Indicates that the axis operating state indicated at the other outputs is valid.
Busy	BOOL	TRUE, as long as the function block is called with Enable = TRUE.
Error	BOOL	TRUE, if an error occurs.
ErrorID	UDINT	If the error output is set, this parameter supplies the error number.
ErrorStop	BOOL	Axis status according to the PlcOpen state diagram
Disabled	BOOL	Axis status according to the PlcOpen state diagram
Stopping	BOOL	Axis status according to the PlcOpen state diagram
StandStill	BOOL	Axis status according to the PlcOpen state diagram
DiscreteMotion	BOOL	Axis status according to the PlcOpen state diagram
ContinuousMotion	BOOL	Axis status according to the PlcOpen state diagram
SynchronizedMotion	BOOL	Axis status according to the PlcOpen state diagram
Homing	BOOL	Axis status according to the PlcOpen state diagram
ConstantVelocity	BOOL	The axis is moving with constant velocity.
Accelerating	BOOL	The axis accelerates.
Decelerating	BOOL	The axis decelerates.
Status	ST_AxisStatus	Extended status data structure with additional status information. (Type: ST_AxisStatus)

Requirements

Development environment	Target system type	PLC libraries to include
TwinCAT v3.0.0	PC or CX (x86 or x64)	Tc2_MC2