January 2012 6.17 Monitoring Functions 991
If the corresponding PLC inputs are switched off, the NC
transmits the nominal speed value "null", braking the drives on the intended
braking ramp (usually at the limit of current)
detects the standstill of the drives after braking and switches off the pulses
of the power stage over the PWM interface (-STO.B.x).
Machine parameter MP_vCtrlTimeSwitchOff serves to monitor the braking
of the drives. The monitoring time for the braking process is defined in
MP_vCtrlTimeSwitchOff. After the monitoring time has expired, the control
checks whether the servo drive is at a standstill. If this is not the case, the
control assumes that a serious error has occurred and switches off the pulses
of the power stages via -STO.B.x (signal to PWM cable).
This ensures that, after a request to switch off the servo drives (e.g.
emergency stop, X150, PLC or alarm), the pulses are safely switched off (via
-STO.B.x) at the latest after the time specified in MP_vCtrlTimeSwitchOff
expires. If the standstill is detected right before expiration of the time defined
in MP_vCtrlTimeSwitchOff, the active braking process is continued and the
pulses are not switched off until after the overlap time.
The time for switching off the pulses (entry in MP_vCtrlTimeSwitchOff) must
be greater than the maximum possible braking time of the axis/spindle that
can occur through electrical braking. Especially for axes/spindles without
mechanical braking, you must ensure that the pulses are not switched off until
after the maximum possible braking time for the axis/spindle that can occur
through electrical braking. Non-decelerated axes/spindles coast to a stop after
pulse switch-off. In the worst case, this can cause damage to the machine.
Specific operating conditions of the machine, such as maximum feed rate,
overload on the axes, etc., must also be taken into account.
MP_vCtrlTimeSwitchOff
Pulse switch-off of the power stages (STO.B.x)
Available from NCK software version: 597 110-05.
Format: Numerical value
Input: 0.100 000 000 to 100 [s]
0 = 3 seconds (default value)
Default: 3 [s]
Access: LEVEL3
Reaction: RUN
The time for switching off the pulses via -STO.B.x, (entry in
MP_vCtrlTimeSwitchOff) must always be greater than the maximum
possible braking time of the axis/spindle that can occur through electrical
braking. However, do not set too large a value in MP_vCtrlTimeSwitchOff.
Otherwise the safety function of the machine parameter cannot be
ensured.
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