Siemens SINUMERIK 828D Function Manual page 44

A2: Various NC/PLC interface signals and functions
1.2 NC/PLC interface signals
Figure 1-3 Trajectory for clamping and "follow-up"
Drives with analog setpoint interface
A drive with an analog setpoint interface is capable of traversing the machine axis with an external setpoint. If
"follow-up mode" is set for the machine axis, the actual position continues to be acquired. Once follow-up mode
has been cancelled, homing is not required.
The following procedure is recommended:
1. Activate follow-up mode:
DB31, ... DBX2.1 = 0 (controller enable)
DB31, ... DBX1.4 = 1 (follow-up mode) (in the same or preceding OB1 cycle)
→ The axis/spindle is operating in follow­up mode
2. Deactivate external controller enable and external speed setpoint
→ Axis/spindle moves with external setpoint
→ NC continues to detect the actual position and corrects the setpoint position to the actual position
3. Deactivate external controller enable and cancel external speed setpoint
→ Axis/spindle stops
4. Canceling follow­up mode
DB31, ... DBX2.1 = 1 (controller enable)
DB31, ... DBX1.4 = 0 (follow-up mode)
→ NC synchronizes to current actual position. The next traversing movement begins at this position.
Note
"Follow­up mode" does not have to be canceled because it only has an effect in
combination with "controller enable".
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Function Manual, 09/2011, 6FC5397-0BP40-2BA0
Basic Functions