Measurement methods (P-AXIS-00516)

P-AXIS-00516

Measurement methods

Description

The parameter defines the source of the probing signal during a measuring travel, e.g. the probing position can be latched in the drive or the probing signal can be provided by the PLC. This setting can also be changed in the NC program by the #MEAS command (see [PROG//Extended programming].

 

This parameter replaces the following old configuration parameters:

Parameter

kenngr.measure.signal

Data type

STRING

Data range

DRIVE_TYPE_DEFAULT

PLC

FIXED_STOP

DRIVE

PLC_EXT_LATCH_CONTROL

PLC_FIRST_EVENT

PLC_TIMESTAMP

EXT_PROBE_WITH_DRIVE (as of V3.1.3080.05)

Axis types

T, R, S

Dimension

T: ----

R,S: ----

Default value

*

Drive types

----

Remarks

If the parameter P-AXIS-00516 is not defined, the measurement method resulting from previous parameters is used for backward compatibility reasons.

* Note: The default value of variables is a blank string.

The meaning of the parameter settings is described in the following table:

Value

Meaning

DRIVE_TYPE_DEFAULT

The CNC uses the default measuring method of the given drive type (see table below /*/)

PLC

This parameter setting reads the probing signal via the Control Unit PLC parameters on the HLI [HLI]. The probing value is the actual value at the moment of the occurrence of the probing signal. As an alternative, the probing position can be specified directly via the control unit Axis control commands.

 

NOTE:

Due to the scanning of the probing signal in the cycle time of the PLC, the accuracy of the probed value is less than the accuracy achieved by using drive-internal probing latches.

 

This setting corresponds to the old parameter kenngr.probing_signal_via_plc (P-AXIS-00257)

FIXED_STOP

This setting searches for a fixed stop during the measuring traverse. In addition, the measurement type 7 (see P-CHAN-00057) must be selected.

 

CAUTION:

The user has to ensure that, during the movement to a fixed stop in the drives affected, a torque limitation is active and that the velocity is low enough.

 

This setting corresponds to the old parameter kenngr.meas_signal_fixed_stop (P-AXIS-00330)

DRIVE

This parameter defines that the probing signal is supplied by the drive. Additional settings in the drive are required (see [FCT-C4]).

This setting corresponds to the old parameters kenngr.mess_signal_taster (P-AXIS-00117), kenngr.mess_signal_sercos (P-AXIS-00116), kenngr.meas_signal_drive (P-AXIS-00269)

PLC_EXT_LATCH_­CONTROL

This setting defines that operation requires an external hardware for the measurement travel. Therefore the CNC informs the PLC via the external measuring interface about the start and end of a measuring travel so that the PLC can enable or disable the measurement hardware accordingly (see [HLI//Measuring with external probing hardware]). This method specifies the probing signal and the measured position via the control units PLC parameters and Axis control commands.

PLC_FIRST_EVENT

This setting corresponds to the value “PLC“. However, the measuring travel stops as soon as the measurement event is detected at an axis measured with this setting. In “PLC mode, however, a measurement event must occur in the control unit PLC parameters at every measured axis.

This setting corresponds to the old parameter kenngr.mess_signal_achs_steuer (P-AXIS-00115)

/*/ Drive type dependent default setting for probing signal source (DRIVE_TYPE_DEFAULT ):

Drive type (see P-AXIS-00020)

Probing signal source default setting

Conventional

Sercos

Profidrive

Beckhoff Lightbus

+-10V via field bus (terminal)

RT-Ethernet

CANopen

CAN-Bus

DRIVE

Drive simulation

Virtual axis

PLC_FIRST_EVENT

Permissible measurement methods dependent on drive type:

Drive type (see P-AXIS-00020)

PLC

FIXED_STOP

DRIVE

PLC_EXT_LATCH_­CONTROL

PLC_­FIRST_-EVENT

Conventional

X

X

X

X

X

Sercos

X

X

X

X

X

Profidrive

X

X

X

X

-

Beckhoff Lightbus

X

X

X

X

-

+-10V via fieldbus (terminal)

X

X

X

X

-

RT-Ethernet

X

X

X

X

-

CANopen

X

X

X

X

-

CAN-Bus

X

X

X

X

-

Drive simulation

X

X

(X)*

X

X

Virtual axis

X

X

(X)*

X

X

(*) Using the measurement simulation (see P-AXIS-00112, [PROG//Extended programming])