User`s manual

4-18 Motion Mate™ DSM314 for Series 90™-30 PLCs User's Manual – January 2001 GFK-1742A
4
5.14 Reversal Compensation.
A compensation factor that allows the servo to reverse direction
and still provide accurate positioning in systems exhibiting backlash. Backlash is exhibited by a
servomotor that must move a small amount (lost motion) before the load begins moving when
direction is reversed. For example, consider a dead bolt door lock. Imagine the servo controls the
key in the lock and the feedback reports bolt movement. When the servo turns the key
counterclockwise, the bolt moves left. However, as the servo turns the key clockwise, the bolt does
not move until the key turns to a certain point. The Reversal Compensation feature adds in the
necessary lost motion to quickly move the servo to where motion will begin on the feedback
device. The DSM314 removes the compensation distance when a move in the negative direction is
commanded, and adds the compensation distance before a move in the positive direction.
Default: 0.
Note
Reversal compensation is not available if the
Follower Control Loop
configuration is set to Enabled.
5.15 Drive Disable Delay.
Servo Drive Disable Delay (milliseconds). The time delay from the time the
zero velocity command is received until the drive enable (digital servo MCON) signal switches off.
Disable Delay is effective when the
Enable Drive
%Q bit is turned off or certain error conditions (Stop
Mode) occur. Disable Delay should be longer than the worst case deceleration time of the servo from
maximum speed. Because turning OFF the
Enable Drive
%Q bit stops the DSM314 from commanding
the servo, there are times when the drive enable signal should stay ON. For example, if the servo runs into
an End of Travel Limit and the drive enable signal was immediately turned OFF due to the error, the servo
may continue moving until it coasted to a stop. Thus, to allow the DSM314 to command and control a fast
stop, the Drive Disable Delay should be longer than the deceleration time of the servo from maximum
speed.
The disable delay may be used to control when torque is removed from the motor shaft.
Applications using an electro-mechanical brake generally need time for the brake to engage prior to
releasing servo torque. The delay should be set to a value longer than the engagement time for the
brake. Default: 100.
5.16 Jog Velocity
. Jog Velocity (User Units/second). The velocity at which the servo moves during
a
Jog
operation.
Jog Velocity
is used by motion programs when no Velocity command is included
in the program.
Jog Velocity
is always used by the %AQ Move Command (27h). Default: 1000.
5.17 Jog Acceleration
. Jog Acceleration Rate (User Units/second/second). The acceleration and
deceleration rate used during
Jog
,
Find Home
,
Move at Velocity, Abort All Moves
and
Normal
Stop
operations. A
Normal Stop
occurs when the PLC switches from Run to Stop or after certain
programming errors (refer to Appendix A).
Jog Acceleration
is used by motion programs when no
Acceleration command is included in the program.
Jog Acceleration
is always used by the %AQ
Move Command (27h). The value of
Jog Acceleration
should be set high enough to perform
satisfactorily during
Abort all Moves
and
Normal Stop
operations. Default: 10000.
Note: A minimum value after scaling is used in the DSM314. This value is determined by the rule:
Jog Acc * (user units/counts) >= 32 counts/sec/sec.
5.18 Jog Acceleration Mode
. Jog Acceleration Mode (LINEAR or S-CURVE). The acceleration
mode for
Jog
,
Find Home
,
Move at Velocity, Abort All Moves
and
Normal Stop
operations. A
Normal Stop
occurs when the PLC switches from Run to Stop or after certain programming errors
(refer to Appendix A). LINEAR (constant acceleration) causes commanded velocity to change
linearly with time. S-CURVE (jerk limited acceleration) causes commanded velocity to change