Measure with external measuring hardware

Basics

If the control of an external measuring hardware required for the measurement run, the external measurement interface between the CNC and the PLC can be used. The CNC informs the PLC of the start and end of a measurement run so that the PLC can enable and disable the measuring hardware accordingly.

CNC – PLC

At the start of a measurement run, the CNC writes the task ‘Enable probe” containing the required parameter number of the probing input and the relevant edge in the interface and ‘Enable probe” and sets please_rw = TRUE.

After reading (please_rw = FALSE) and enabling the measuring hardware, the PLC acknowledges the task with done_w = TRUE). Accordingly, if the position latch is successful or aborted, the CNC signals the end of the measurement run with a CNC reset. Please note that the PLC must always acknowledge these tasks.

For more information on the interface structure, refer to the HLI documentation ([HLI]).

After the probing event occurs, the PLC writes the detected probing position to the probing_position control unit and then signals the probing event to the control unit probing_signal (see [HLI//Control commands of an axis]).

Notice

When the external measuring interface is used, the measurement signal of the probing_signal control unit is not dependent on the relevant measuring edge P-AXIS-00518. A positive edge always signals the successful detection of a measured value in the external measuring hardware.

Notice

If the probing_signal control unit is not enabled when the probing event occurs, the actual value at the time the probing signal occurs is used.

Axis parameter

The following axis parameters are required for measuring with the CNC-PLC interface:

Alternatively, the measuring interface can also be enabled in the NC program by the #MEAS command (see [PROG//Extended programming]).