Siemens SINUMERIK 808D Function Manual page 14

Deactivation:
Cancellation of the "Axis/spindle disable" (edge change 1 → 0) does not take effect until the axis/spindle is stationary (i.e. an
interpolation setpoint is no longer present). The new movement begins with new specified setpoints. (E.g. new program
block with movement specifications in "AUTO" operating mode.)
Note: actual values vary between simulated and real axis!
Follow-up mode (DB380x.DBX1.4)
If an axis/spindle is operating in follow-up mode, its setpoint position is made to track the current actual value position. The
position setpoint in follow-up mode is not defined by the interpolator but derived from the actual position value. Since
recording of the actual position value of the axis continues, it is not necessary to re-home the axis when follow-up mode is
cancelled.
Standstill, clamping and positioning monitoring are not effective in follow-up mode.
Effect:
The IS "Follow-up mode" is only of relevance if the drive controller enable has been removed (e.g. by IS "drive enable" = 0
signal or because of a fault in the control system), or because drive enable is being re-issued.
IS "Follow-up mode" = 1:
If "Drive enable" is removed the position setpoint of the relevant axis is continuously corrected to the actual value. This state
is signaled to the PLC by means of IS "Follow-up mode active" (DB390x.DBX1.3). If the "drive enable" is enabled again and
a part program is active, a control internal re-positioning operation is initiated (REPOSA: linear approach with all axes) to the
last programmed position. Otherwise, the axis movement starts at the new actual position (which may have changed).
IS "Follow-up mode" = 0:
If "Drive enable" is removed, the old position setpoint is maintained. If the axis is pushed out of position, a following error
between position setpoint and actual value results which is corrected when IS "drive enable" is set. The axis movement
starts from the setpoint position valid before the "drive enable" was removed. IS "Followup mode active" (DB390x.DBX1.3) is
set to 0 signal during the "Hold" state. Clamping or standstill monitoring is active.
Position measuring system 1 (DB380x.DBX1.5)
A position measuring system may be connected to the spindle. In this case the signal for the spindle has to be set.
Axes always require this signal. In this case, a position measuring system must be installed.
Drive enable (DB380x.DBX2.1)
When the drive enable is activated for the drive, the position control loop of the axis/spindle is closed. The axis/spindle is
then subject to position control.
When the drive enable is removed the position control loop and, with a delay, the speed control loop of the axis/spindle are
opened.
IS "Position controller active" (DB390x.DBX1.5) is set to 0 signal (checkback).
Activation:
The drive enable for the drive can be set and removed from the following places:
1. From the PLC user program with interface signal "Drive enable" (in normal cases)
Application: Removal of drive enable before clamping an axis/spindle.
2. The drive enable is cancelled internally by the control when certain faults occur in the machine, the drive, the position
measuring system or the control (when faults occur)
Application: The traversing axes must be brought to a standstill by a rapid stop due to a fault.
3. By the control if the following event occurs: IS "EMERGENCY STOP" (DB2600.DBX0.1) is active
Removal of drive enable for a moving axis/spindle:
● The spindle is braked to standstill with rapid stop taking account of MD36610 AX_EMERGENCY_STOP_TIME (duration
of the braking ramp in error states). Alarm 21612 "Controller enable reset during movement" is then triggered.
● The position control loop of the axis/spindle is opened. Checkback signal to PLC with IS "Position controller active"
(DB390x.DBX1.5) = 0 state. The timer for the drive enable delay time (MD36620 SERVO_DISABLE_DELAY_TIME
(shutdown delay of drive enable)) is also started.
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Function Manual
01/2017