Enabling The Measurement System - Siemens SINUMERIK 840D Function Manual

R1: Referencing
10.9 Referencing with absolute encoders
Supplementary conditions
● A reference point offset (MD34090 $MA_REFP_MOVE_DIST_CORR) may not be
parameterized.
This MD describes, in connection with absolute encoders, the offset between machine and
absolute encoder zero, and it therefore has a different meaning.
● The load-side zero mark search rate (MD34040 $MA_REFP_VELO_SEARCH_MARKER)
should not exceed the limiting frequency of the absolute trace of the encoder
(MD36302 $MA_ENC_FREQ_LIMIT_LOW)
. If the speed is too high, absolute information cannot be read any more, and thus, no
equivalent zero marks are generated.
● If no zero mark is found within the parameterized path (MD34060
$MA_REFP_MAX_MARKER_DIST), an alarm is output:
● The following MD must be set if the absolute encoder retains even the referenced status
through POWER OFF, besides the last position:
MD34210 $MA_ENC_REFP_STATE = 2
Data backup and standard commissioning
Some properties of an absolute encoder restrict the transfer of a commissioning archive to
other machines. The following machine data must be checked and possibly corrected after
loading a commissioning archive to the controller:
● MD30250 $MA_ACT_POS_ABS (internal encoder position)
● MD30270 $MA_ENC_ABS_BUFFERING (traversing range extension)
● MD34090 $MA_REFP_MOVE_DIST_CORR (absolute offset)
● MD34210 $MA_ENC_REFP_STATE (adjustment status)
● MD34220 $MA_ENC_ABS_TURNS_MODULO (modulo range)
● MD34230 $MA_ENC_SERIAL_NUMBER (encoder serial number)
10.9.8

Enabling the measurement system

The measuring system of a machine axis is activated in the following cases:
● Power up of the control (POWER ON)
● Activation of the measuring system via interface signal (deselection of "parking"):
DB31, ... DBB1.5 / 1.6 (position measuring system 1/2)
DB31, ... DBB2.1 (servo enable)
● Violation of the assigned encoder limit frequency (spindles):
MD36300 $MA_ENC_FREQ_LIMIT
When the measuring system is activated, the NC synchronizes the actual value system of the
machine axis with the current absolute value. Traversing is disabled during synchronization for
axes but not for spindles.
330
Axes and spindles
Function Manual, 06/2019, A5E47437747B AA