HEIDENHAIN iTNC 530 Service Manual page 688

At the same time, HEIDENHAIN recommends using the "global axis enabling" of the controller
External
unit (CC) via (X42/33; I32) or the axis-specific "axis enables" of the CC via X150/X151, which are
EMERGENCY STOP
also integrated in the external emergency stop.
via CC
If these are switched off, then when there is an emergency stop of the controller unit (CC) ...
(axis releases)
MP2173.x
Input:
3 – 688
the nominal speed value "null" is output, braking the drives on the intended braking ramp
(usually at the limit of current).
The pulses of the power stages are normally switched off after the braking process and the
overlap time (MP2308). MP2173.x serves to monitor the braking of the drives. The monitoring
time for the braking process is defined in MP2173.x. 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 (via SH2) the pulses of the power
stages. 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 SH2) at the latest after the
time specified in MP2173.x expires. If the standstill is detected right before expiration of the
time defined in MP2173.x, 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 MP2173.x) 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. Undecelerated 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.
Note
The time for switching off the pulses (via SH2, entry in MP2173.x) must always be greater
than the maximum possible braking time of the axis/spindle that can occur through electrical
braking.
However, the time in MP 2173 should not be too large so that the safety function of the
machine parameter is still ensured.
Pulse switch-on of the power stage
0.2 to 100.000 [s]
0 = 3 seconds (default value)
HEIDENHAIN Service Manual iTNC 530