R1: Reference point approach
15.9 Referencing with absolute value encoders
Basic Functions
Function Manual, 09/2011, 6FC5397-0BP40-2BA0
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Determining the encoder limit frequency
The encoder limit frequency to be parameterized is derived from the smaller of the two following limit speeds:
• Encoder
The limit speed or encoder limit frequency is listed in the data sheet of the encoder (e.g., limit speed = 2000
[rpm])
• NC
Due to the NC-internal evaluation process, the maximum limit speed for which error-free calculation of the
absolute value by the NC is possible is 4 encoder revolutions per interpolation cycle.
For an interpolation cycle of, for example, 12 ms: Limit speed = 4 / 12 ms = 20,000 rpm
The limiting frequency corresponding to the limiting speed is calculated to be:
15.9.10
Referencing variants that are not supported
The following referencing variants are not supported when used with absolute encoders:
• Referencing / calibrating with encoder zero mark
• Distancecoded reference marks
• BERO with two-edge evaluation
MD31020 $MA_ENC_RESOL (Encoder lines per revolution)
MD10050 $MN_SYSCLOCK_CYCLE_TIME (System clock cycle)
MD10070 $MN_IPO_SYSCLOCK_TIME_RATIO (Factor for interpolator cycle)
Note
The position control switching speed relevant for spindles is set according to the encoder
limiting frequency of the absolute value encoder of the spindle:
MD35300 $MA_SPIND_POSCTRL_VELO (position control switching speed)
MD36300 $MA_ENC_FREQ_LIMIT (Encoder limit frequency)
0'
0'
0'0'
