Configuring the measuring system

The measuring system is used by the CNC to locate the workpiece on the linear conveyor. The channel parameters P-CHAN-00368 to P-CHAN-00373 describe the location of the measuring system relative to the machine coordinate system.

In the application, a measured value corresponds to a position of the linear conveyor at a specific point in time. The CNC interprets this position as the position of the front edge of the workpiece at the measuring system position.

The parameter P-AXIS-00516 can be used to configure how the measured value for the spindle axis representing the linear conveyor is transferred to the CNC. Typically, three different measuring methods are recommended for this application:

1. The CNC controls the linear conveyor and a maximum of one measured value is always presented: direct measurement via the drive interface. In this variant, the PLC does not possess any measuring logic.
2. The linear conveyor is controlled externally and a maximum of one measured value is always presented: The measuring trigger is activated by the PLC ( P-AXIS-00516 == PLC and lr_mc_control.probing_signal) and the measuring position is read by the drive interface.
3. The linear conveyor is controlled externally and measured values must be saved because new measured values occur and previous workpieces are not yet fully processed: The measuring trigger (P-AXIS-00516 == PLC and lr_mc_control.probing_signal) and the measuring position (lr_mc_control.probing_position) are specified by the PLC. In this case, the PLC must possess the logic to assign the various measured values and the appropriate NC program.

Checking the measuring system configuration

A measurement should be triggered to check whether the measuring system is correctly configured and the following variables are acquired:

• Measuring trigger: The variable lr_mc_control.probing_signal should be acquired when the PLC sends the trigger; the variable lr_state.probe_actuated_r should be acquired when the measurement is sent via the drive interface.
• Measured value: The variable lr_mc_control.probing_signal should be acquired when the PLC sends the trigger; the variable lr_state.probe_actuated_r should be acquired when the measurement is sent via the drive interface.
• Workpiece position: The variable bahn_state.conveyor_data.current_pos_master indicates the current workpiece position on the linear conveyor. If a measuring system is installed that can also measure the actual workpiece position on the linear conveyor, this signal would also be useful.
• The workpiece position must be identical to the actual position after a measurement in order to verify that the measuring unit is configured correctly. This means that the workpiece position jumps to the configured X offset of the measuring unit (P-CHAN-00368) at the time of measurement. The position should then continue to move by the same position as the linear conveyor.