Siemens SINUMERIK 840D sl Function Manual page 506

M5: Measurement
8.4 Axial measurement
$AA_MM1[axis] = trigger event 1, measured value from encoder 1
$AA_MM2[axis] = trigger event 1, measured value from encoder 2
Two trigger events
$AA_MM1[axis] = trigger event 1, measured value from encoder 1
$AA_MM2[axis] = trigger event 1, measured value from encoder 2
$AA_MM3[axis] = trigger event 2, measured value from encoder 1
$AA_MM4[axis] = trigger event 2, measured value from encoder 2
PLC service display
For further information about the functional test of the probe, see Section "Measurement
results (Page 500)".
Read measurement results of MEAC
All measurements are written to a previously defined FIFO variable. The possible number of
measured values is defined via the machine data (see Section "Measurement (Page 501)").
● The correct operation is executed reliably for PROFIBUS telegram 391 for the ratios of the
IPO clock / position controller cycle ≤ 8:1.
● The correct operation is executed reliably for PROFIBUS telegram 395 for the ratios of the
IPO clock / position controller cycle ≤ 4:1.
● The contents of the FIFO memory can be read only once. When measurement results are
used more than once, the read-out values must be buffered in the user data.
Endless measuring
In order to implement endless measuring, FIFO values must be read cyclically from the part
program. The frequency with which the measured values are read from the FIFO memory and
processed must correspond to the writing frequency of the NC.
The number of valid entries is readable in a FIFO variable.
If measuring is to be terminated after reaching a defined number of measured values, the
measurement job must explicitly be deselected in the program.
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Function Manual, 10/2015, 6FC5397-1BP40-5BA3
Extended Functions