Omron CJ1W-NC271 - 12-2009, Operation Manual

Page: 411 / 687

383
Torque Limits
Section 10-4
Positioning that Does Not Reach Target Position (Example: Pushing a Load)
Note In applications such as pushing a load, when using the torque limit function to
limit the output torque of the Servomotor and stop the machine, the command
present position reaches the target position while the feedback present posi-
tion does not, which causes the pulses to accumulate for the position devia-
tion in the Servo Drive’s deviation counter. To change movement to the
opposite direction, send the operating command with the Current Limit Desig-
nation Bit setting enabled in the pushing direction.
If the Current Limit Designation Bit setting is disabled for the direction in which
the load is being pushed when operation is started in the opposite direction
(i.e., an operating command is sent without specifying the torque limit), torque
will be generated in the pushing direction at the start of operation. This is due
to the position deviation accumulated in the pushing direction and may result
in damage to the machine or an accident.
ABSOLUTE MOVEMENT
(word a, bit 03)
Forward Rotation Current
Limit Designation Bit (word
a+16, bit 14)
Receiving Command Flag
(word b, bit 00)
Busy Flag (word b, bit 13)
Torque Limit Status Flag
(word b+1, bit 09)
Position
Pushing direction target
position (position command
value)
Pushing stop position
Speed
Pushing direction target
speed (speed command
value)
Position deviation
Start Pushing
Start in opposite
direction
Time in which accumulated position deviation is consumed
a = Beginning word of Axis Operating Output Areas specified in Common Para (Axis No.
−
1)
×
25
b = Beginning word of Axis Operating Input Areas specified in Common Para (Axis No.
−
1)
×
25
Time
Broken line: Servomotor's actual speed
Time
Time
Broken line: Feedback present position
(Servomotor's actual position)
Solid line: Command present position
This flag remains ON for the time the output torque is limited by the limit value.
When positioning is not
completed and the position
deviation due to pushing
remains, the axis's Busy
Flag will remain ON until
DECELERATION STOP or
other stop operation is
executed.
When position deviation has accumulated due to pushing,
torque in the pushing direction that is greater than the limit
value will be generated if the forward rotation current limit is
cleared, which may result in damage to the device.
Therefore, specify a torque limit in the pushing direction also
when starting operation in the opposite direction.
Solid line: Command speed