Overtravel And Related Settings; Overtravel Signals - YASKAWA SGD7S Product Manual

5.10

Overtravel and Related Settings

Overtravel is a safety 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 CCW-OT (CCW Drive Prohibit) and the CW-OT (CW Drive
Prohibit) signals. You use the CCW-OT and CW-OT signals to stop the machine by installing
limit switches at the positions where you want to stop the machine that is operated by the Ser-
vomotor.
A SERVOPACK wiring example is provided below.
Rotary Servomotors
Servomotor
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.
 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 (CCW-OT and
CW-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 a hard stop (PnB1A = 0001 hex)
or set a smooth stop (PnB1A = 0002 hex).
 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 a hard stop (PnB1A = 0001 hex) or set a smooth stop (PnB1A =
0002 hex).
5.10.1

Overtravel Signals

The overtravel signals include the CCW-OT (CCW Drive Prohibit) and the CW-OT (CW Drive
Prohibit) signals.
Type Signal
CCW-OT
Input
CW-OT
Even during overtravel, you can input a reference to drive the motor in the opposite direction.
Forward direction of motor
SERVOPACK
CN1
Limit Limit
CW-OT
9
switch switch
CCW-OT
8
CAUTION
Connector Pin No.
Prohibits CCW drive (counterclockwise as viewed from the
CN1-8
load end of the motor).
Prohibits CW drive (clockwise as viewed from the load end
CN1-9
of the motor).

5.10 Overtravel and Related Settings

5.10.1 Overtravel Signals

Linear Servomotors
Servomotor
Forward direction
Limit Limit
CW-OT
switch
switch
CCW-OT
Meaning
SERVOPACK
CN1
9
8
5
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