Siemens SINUMERIK 840D Function Manual page 833

Maximum encoder frequency exceeded.
If the spindle speed reaches a speed (large S value programmed), which exceeds the
maximum encoder limit frequency (the maximum mechanical speed limit of the encoder must
not be exceeded), the synchronization is lost. The spindle continues to rotate, but with reduced
functionality.
With the following functions, the spindle speed is reduced until the active measurement system
is operating below the encoder limit frequency again:
● Thread cutting (G33, G34, G35)
● Tapping without compensating chuck (G331, G332)
● Revolutional feedrate (G95)
● Constant cutting rate (G96, G961, G97, G971)
● SPCON (position-controlled spindle operation)
When the encoder limit frequency is exceeded
NC/PLC IS:
DB31, ... DBX60.4 (referenced/synchronized 1)
or
DB31, ... DBX60.5 (referenced/synchronized 2)
are reset for the measurement system in question and NC/PLC IS:
DB31, ... DBX60.2 (encoder limit frequency 1 exceeded)
or
DB31, ... DBX60.3 (encoder limit frequency 2 exceeded)
are set.
If the spindle is in axis mode, the maximum encoder limit frequency must not be exceeded.
The maximum velocity (MD32000 $MA_MAX_AX_VELO) must lie below the maximum
encoder limit frequency; otherwise, alarm 21610 is output and the axis is brought to a standstill.
Maximum encoder limit frequency undershot
If the maximum encoder frequency limit has been exceeded and the speed subsequently falls
below the maximum encoder limit frequency (smaller S value programmed, spindle override
switch changed, etc.), the spindle is automatically synchronized with the next zero mark or the
next proximity switch signal. The new synchronization will always be carried out for the active
position measuring system that has lost its synchronization and whose maximum encoder limit
frequency is currently undershot.
Special features
If the following functions are active, the maximum encoder frequency cannot be exceeded:
● Spindle positioning mode, axis mode
● Thread cutting (G33, G34, G35)
● Tapping without compensating chuck G331, G332 (does not apply to G63)
● Revolutional feedrate (G95)
● Constant cutting rate (G96, G961, G97, G971)
● SPCON
Axes and spindles
Function Manual, 06/2019, A5E47437747B AA
S1: Spindles
18.8 Spindle monitoring
833