YASKAWA MP2000 Series User Manual page 191

7.2 Motion Command Details
7.2.3 Zero Point Return (ZRET)
[ o ] N-OT Signal Method (OW3C = 17)

Operation after Zero Point Return Starts
Travel is started at the approach speed in the negative direction until the stroke limit is reached.
When the N-OT signal is detected, the direction is reversed to return at the positioning speed.
When a change in the N-OT signal status from ON to OFF is detected during the return, the positioning is performed.
When the positioning has been completed, a machine coordinate system is established with the final position as the
zero point.
 The moving amount after the change of the N-OT signal status is detected is set in the Zero Point Return Travel Dis-
tance. The positioning speed is set in the Speed Reference Setting.
 If a positive value is set for the approach speed, the command will end in an error.
 If an OT signal is detected during the positioning speed operation, an OT alarm will occur.
 Detecting the change in the OT signal status is performed using software processing. The position where positioning
is completed will depend on the high-speed scan setting, positioning speed, etc. Do not use this method if repeat
accuracy is required in the position where the zero point return operation is completed.
 The stopping method when the OT signal is detected depends on the setting of SERVOPACK parameters.

Parameters to be Set
Parameter
OW03,
Bits 0 to 3
OL10
OW18
OW3C
OL3E
OL42
7-52
Speed Reference Setting
(OL 10)
Zero Point
Return Travel
Distance
(OL 42)
Zero Point
Approach Speed
(OL
N-OT (DI_4)
Name
Speed Unit Selection
Speed Reference
Setting
Override
Zero Point Return
Method
Approach Speed
Zero Point Return Travel
Distance
Start
3E)
Select the setting unit for OL10 (Speed Reference Setting) and
OL3E (Approach Speed).
0: Reference unit/s
n
1: 10 reference units/min
2: Percentage of rated speed (1 = 0.01%)
3: Percentage of rated speed (1 = 0.0001%)
Set the positioning speed to use after detecting the N-OT signal. The sign is
ignored.
The travel direction will depend on the sign of the Zero Point Return Travel
Distance.
Setting to 0 or a negative value will result in an error.
This parameter allows the travel speed to be changed without changing the
Speed Reference Setting (OL10). The setting can be changed during
operation.
Setting range: 0 to 32767 (0 to 327.67%)
Setting unit: 1 = 0.01%
17: N-OT Only Method
Set the speed to be used at zero point return start.
Only a negative value can be used. Setting to 0 or a positive value will result
in an error.
Set the travel distance from the point where the N-OT signal is detected.
The travel direction will depend on the sign.
Always set to a positive value when using N-OT Only Method.
P-OT (DI_3)
Setting