MC_ReadStatus

MC_ReadStatus 1:

MC_ReadStatus 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

Enable

As long as Enable = TRUE, the axis operating state is updated with each call of the function block.

General rules for MC function blocks

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

Valid	Indicates that the axis operating state indicated at the other outputs is valid.
Busy	Indicates that the function block is active.
Error	Becomes TRUE if an error occurs.
ErrorID	If the error output is set, this parameter supplies the error number
ErrorStop	Axis status according to the PlcOpen state diagram
Disabled	Axis status according to the PlcOpen state diagram
Stopping	Axis status according to the PlcOpen state diagram
StandStill	Axis status according to the PlcOpen state diagram
DiscreteMotion	Axis status according to the PlcOpen state diagram
ContinousMotion	Axis status according to the PlcOpen state diagram
SynchronizedMotion	Axis status according to the PlcOpen state diagram
Homing	Axis status according to the PlcOpen state diagram
ConstantVelocity	The axis is moving with constant velocity
Acceleration	The axis accelerates.
Decelerating	The axis decelerates.
Status	Extended status data structure with additional status information.

General rules for MC function blocks

Inputs/outputs


VAR_IN_OUT
    Axis    : AXIS_REF;
END_VAR

Axis

Axis data structure

The axis data structure of type AXIS_REF addresses an axis unambiguously within the system. Among other parameters it contains the current axis status, including position, velocity or error state.