Overtravel And Related Settings - YASKAWA SGD7S Product Manual

5.12 Overtravel and Related Settings

5.12

Overtravel and Related Settings

Overtravel is a function of the SERVOPACK that forces the Servomotor to stop in response to a
signal input from a limit switch that is activated when a moving part of the machine exceeds the
safe range of movement.
The overtravel signals include the P-OT (Forward Drive Prohibit) and the N-OT (Reverse Drive
Prohibit) signals.
You use the P-OT and N-OT signals to stop the machine by installing limit switches at the posi-
tions where you want to stop the machine that is operated by the Servomotor.
A SERVOPACK wiring example is provided below.
Using the overtravel function is not necessary for rotating applications such as rotary tables
and conveyors. No wiring for overtravel input signals is required.
This section describes the parameters settings related to overtravel.
5-32
Rotary Servomotors
Forward direction of motor
Servomotor
Limit
Limit
switch
switch
 To prevent accidents that may result from contact faults or disconnections, use normally
closed limit switches.
Do not change the default settings of the polarity of the overtravel signals (P-OT and N-OT).
 If you use a Servomotor for a vertical axis, the /BK (Brake) signal will remain ON (i.e., the
brake will be released) when overtravel occurs. This may result in the workpiece falling when
overtravel occurs. To prevent the workpiece from falling, set Pn001 to n.1 to place the
Servomotor in a zero-clamped state when it stops.
 A base block state is entered after stopping for overtravel. This may cause the Servomotor
to be pushed back by an external force on the load shaft. To prevent the Servomotor from
being pushed back, set Pn001 to n.1 to place the Servomotor in a zero-clamped state
when it stops.
Linear Servomotors
SERVOPACK
CN1
N-OT
43
P-OT
42
CAUTION
Servomotor
Forward direction
SERVOPACK
CN1
Limit
Limit
N-OT
43
switch
switch
P-OT
42