Measurement Accuracy And Functional Testing; Measuring Accuracy; Probe Functional Test - Siemens SINUMERIK 808D Function Manual

13.4

Measurement accuracy and functional testing

13.4.1

Measuring accuracy

Accuracy
The propagation time of the measuring signal is determined by the hardware used. The delay times are in the µs range plus
the probe response time.
The measurement uncertainty is calculated as follows:
Measurement uncertainty = measuring signal propagation time x traversing velocity
Correct results can only be guaranteed for traversing velocity where not more than one triggering signal arrives per position
controller cycle.
13.4.2

Probe functional test

Example of functional test
The functional test for the probe is conducted favorably via an NC program.
%_N_PRUEF_MESSTASTER_MPF
N10; R10
N20; R11: measurement in X axis
N30 T1 D1
N40 ANF: G0 G90 X0 F150
N50 MEAS=1 G1 X100
N60 STOPRE
N70 R10=$AC_MEA[1]
N80 IF R10==0 GOTOF FEHL1
N90 R11=$AA_MW[X]
N95 M0
N100 M2
N110 FEHL1: MSG
N120 M0
N130 M2
Example of repeat accuracy
This program allows the measuring scatter (repeat accuracy) of the entire measuring system (machine-probe-signal
transmission) to be calculated.
In the example, ten measurements are taken in the X axis and the measured value recorded in the workpiece coordinates.
It is possible to determine the so-called "random dimensional deviations" which are not subject to any trend.
%_N_CHECK_ACCURATE_MPF
N05; R11
N06 R12=1
N10; R1 to R10
N15 T1 D1
N20 ANF: G0 X0 F150
N25 MEAS=+1 G1 X100
N30 STOPRE
N35 R11= $AC_MEA[1]
N37 IF R11==0 GOTOF FEHL1
N40 R[R12]=$AA_MW[X]
N50 R12=R12+1
N60 IF R12<11 GOTOB ANF
N65 M0
N70 M02
N80 FEHL1: MSG
N90 M0
N95 M02
The measurement results R1 to R10 can be read after selecting the parameter display.
Function Manual
01/2017
;Testing program probe connection
;Flag for trigger status
; Preselect tool offset for probe
;Starting position and meas. velocity
; Measurement at measuring input 1 in the X axis
; Read switching signal at 1st measuring input
;Evaluation of signal
;Read in measured value in workpiece coordinates
; Probe not switching!
; Switching signal
; Counter
; MEAS_VAL_IN _X
; Start conditions, preselect tool offset for
; probe
;Prepositioning in the measured axis
; Measurement at 1st measuring input with
;rising switching edge, in the X axis
; Stop decoding for subsequent evaluation of the
; result (automatically executed when reading
; MEA)
; Read switching signal at 1st measuring input
;Check switching signal
;Read measured value in workpiece ;coordinates
;Repeat 10 times
; Probe not switching
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