4.8 Overtravel Function
4-35
Feed Axis
Operation
4.8
Overtravel Function
Overtravel forces the machine to stop when any moving part of the machine exceeds the safe range of move-
ment by forcibly stopping the servomotor with a limit switch signal input.
Overtravel is not always required for rotational applications such as a rotary table or magazines, and in those
cases the overtravel input signals do not need to be wired.
The overtravel function is not affected by the set value of Pn01E.0 (Motor Type/Application Selection Set-
ting).
There are two ways to implement overtravel protection: with the overtravel function built into the SERVO-
PACK or by implementing the overtravel function at the host controller.
4.8.1
Using the SERVOPACK Overtravel Function
For linear drive applications, connect the limit switches to the P-OT and N-OT pins of CN1 as shown in the
following figure to prevent damage to the machine.
Use an NC contact to prevent accidents in case there are any problems with the limit switch contacts or wiring.
Warnings for External Forces Applied to Servomotor Axes during Overtravel
Vertical Axes:
When overtravel occurs, the SERVOPACK’s /BK signal turns ON (break released). This may cause moving
parts (e.g., workpieces) to fall from vertical axes (including inclined axes). To prevent moving parts from fall-
ing, set the zero clamp state (Pn001.1 = 1) after the servomotor stops.
Other Axes Subject to External Forces:
When overtravel occurs, the axis becomes base blocked after it stops. In some cases, the servomotor may be
pushed back by external forces from the load axis. To prevent this from occurring, set the zero clamp state
(Pn001.1 = 1) after the servomotor stops.
N-OT
P-OT
CN1
Motor forward
direction
Servomotor
Limit switch
Limit switch
SERVOPACK