Position Monitoring - Siemens SINUMERIK 808D Function Manual

4.2.2

Position monitoring

Function
In order to ensure that an axis reaches the required position within the specified time, the timer that can be configured in
MD36020 POSITIONING_TIME (time delay exact stop
fine) is started at the end of each motion block (setpoint has reached target) and, when the timer runs out, a check made to
ascertain whether the axis has reached its setpoint within
the tolerance of MD36010 STOP_LIMIT_FINE (exact stop fine).
For details on "Exact stop coarse and fine" see Chapter "Continuous Path Mode, Exact Stop and Look-Ahead (Page 31)"
Relation between position, standstill, and clamping monitoring:
Effectiveness
Positioning monitoring is always activated after the termination of motion blocks "according to the setpoint" (setpoint has
reached destination).
Position monitoring is active for axes and position-controlled spindles.
Deactivation
When the programmed "Exact stop limit fine" has been reached or a new setpoint has been output (e.g. for positioning
according to "Exact stop coarse" followed by a block change), the position monitoring is deactivated.
Effect
If the limit value for "Exact stop fine" has not yet been reached when the positioning monitoring time has elapsed, the
following action is performed:
● Output of alarm 25080 "Positioning monitoring"
● The affected axis/spindle is brought to a standstill using a rapid stop (with open position control loop) along a speed
setpoint ramp.
The braking ramp duration is set in
MD36610 AX_EMERGENCY_STOP_TIME (braking ramp duration for error states).
● If the axis/spindle is involved in interpolation with other axes/spindles, these are stopped using a rapid stop with following
error reduction (default for partial position setpoint = 0).
Cause of error/Remedy
● Position controller gain too low --> change machine data for position controller gain
MD32200 POSCTRL_GAIN (servo gain factor)
Function Manual
01/2017
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