3 Safety-Related Functions 11.03
3.5 Safely-reduced speed (SG)
© Siemens AG 2003 All Rights Reserved
3-96 SINUMERIK 840D/SIMODRIVE 611 digital SINUMERIK Safety Integrated (FBSI) - Edition 11.03
3.5.2 Limiting the setpoint speed
In order to limit the setpoint speed as a function of the active safety monitoring,
MD 36933: $MA_SAFE_DES_VELO_LIMIT is specified. This machine data is
not included in the axial checksum MD 36998: $MA_SAFE_ACT_CHECKSUM,
so that changes can be made to the MD for the acceptance test without having
to change the checksum again.
MD = 0%: Setpoint limiting not active
MD > 0%: Setpoint limiting = active SG limit multiplied by MD value
For SBH setpoint limit = 0
MD = 100%: Setpoint limiting = active SG limit
For SBH setpoint limit = 0
• The function is effective in one channel in the NCK interpolator. The safety
monitoring channel provides a limit value which corresponds to the
selected safety monitoring type.
• The function influences both axes and spindles.
• The active setpoint limit can be viewed in the safety service display:
Display value = -1. corresponds to "setpoint limiting not active"
Display value >= 0. corresponds to "setpoint limiting active"
• The setpoint limit is changed over when the SGEs are changed over:
SGE "SBH/SG de-selection"
SGE "SBH de-selection"
SGEs "Active SG stage, bit 0, 1"
SGEs "SG override, bit 0, 1, 2, 3"
Beyond that, internal changeover operations in SBH take effect as the
result of a stop response (stop D, C, E)
• When a changeover is made via SGEs, the states of
both
monitoring
channels are viewed to take into account differences in the times. This
results in the following rules:
1. Changing-over from non-safe operation in SG/SBH
There is no delay (VELO_SWITCH_DELAY), so that this changeover
must always be performed at zero speed or below the defined SG
limit.
2. Changing-over from SGx to SGy
a) SGx > SGy (braking): A lower setpoint is entered as soon as
changeover is detected in one of the two channels.
B) SGx < Sgy (acceleration): A higher setpoint is only entered if both
channels have changed over.
3. Changing-over from SG to SBH (braking)
A lower setpoint (= 0) is entered as soon as the changeover has been
detected in one of the two channels.
4. Changing-over from SBH to SG (acceleration)
A higher setpoint is only entered if both channels have changed over.
5. Changing over from SBH/SG into non-safe operation (acceleration)
A higher setpoint is only entered if both channels have changed over.
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