AXIS_REF
The AXIS_REF data type contains axis information. AXIS_REF is an interface between the PLC and the DRIVE. It is added to MC function blocks as axis reference.
TYPE AXIS_REF :
VAR_INPUT
PlcToDrive AT %Q* : PLCTODRIVE_AXIS_REF;
Parameter : ST_AxisParameter;
END_VAR
VAR_OUTPUT
DriveToPlc AT %I* : DRIVETOPLC_AXIS_REF;
WcState AT %I* : DRIVETOPLC_WCSTATE;
InfoData AT %I* : DRIVETOPLC_IFODATA;
Status : ST_AxisStatus;
END_VAR
END_TYPE
AXIS_REF elements
Name | Description |
|---|---|
PlcToDrive | Data structure that is cyclically exchanged between PLC and DRIVE. The MC function blocks communicate with the DRIVE via this data structure and send control information and commands from the PLC to the DRIVE. The data structure is automatically placed in the output process image of the PLC and must be connected to the input process image of a DRIVE in the TwinCAT development environment. |
Parameter | Data structure for parameterization of the axis (type: ST_AxisParameters). |
DriveToPlc | Data structure that is cyclically exchanged between PLC and DRIVE. The MC function blocks communicate with the DRIVE via this data structure and receive status information from the DRIVE. The data structure is automatically placed in the input process image of the PLC and must be connected to the output process image of a DRIVE in the TwinCAT System Manager. The DRIVETOPLC structure contains all main state data for an axis such as position, velocity and instruction state. Since data exchange takes place cyclically, the PLC can access the current axis state at any time without additional communication effort. |
WcState | Data structure that is cyclically exchanged between PLC and DRIVE and contains the WcState of the DRIVE. The data structure is automatically placed in the input process image of the PLC and must be connected to the output process image of a DRIVE in the TwinCAT development environment (type: DRIVETOPLC_WCSTATE). |
InfoData | Data structure that is cyclically exchanged between PLC and DRIVE and contains ADS information for accessing DRIVE parameters. The data structure is automatically placed in the input process image of the PLC and must be connected to the output process image of a DRIVE in the TwinCAT development environment (type: DRIVETOPLC_INFODATA). |
Status | Data structure containing additional or processed status information for an axis (type: ST_AxisStatus). This data structure is not refreshed cyclically, but has to be updated through the PLC program. For this purpose MC_ReadStatus or alternatively the action "ReadStatus" of AXIS_REF can be called (see sample). |
Sample:
VAR
Axis1 : AXIS_REF (* axis data structure for Axis-1 *)
END_VAR
(* program code at the beginning of each PLC cycle *)
Axis1.ReadStatus();
(* alternative program code at the beginning of each PLC cycle *)
Axis1();
The call of "ReadStatus" or "Axis1" should be made once at the beginning of each PLC cycle. The current status information can then be accessed in AXIS_REF from the whole PLC program. Within a cycle the status does not change.