Rockwell Automation 1771-QA Stepper Positioning Assembly User Manual - Manual (Page 26)

3–4 Programming and Operation
Publication 1771-UM002A–EN–P – May 2000
Jog
A jog allows an axis to be manually controlled by an operator
independent of other axes in the system. This can be done at any
time except when a positioning profile is in progress. A jog can be
initiated by a hardware or software input to the stepper positioning
assembly.
Jog data is one move block that controls one axis. The job move
block typically is contained in a separate 1-move (10-word) moveset.
The jog move block can also be contained in a moveset with other
moves. If so, the jog must be the first move of the moveset. The
remaining moves will be ignored as a result of the stepper controller
module processing the jog move block. After the jog has been
executed as needed, the remaining moves can be initiated by again
transferring the same moveset to the stepper controller module. This
time a skip bit must be set in the jog data and the jog load bit must be
cleared. (These bits are described in section titled “Move Block,”
Bit 02 and 03). The positioning profile will then start with move two
and ignore the jog data.
The jog can be initiated by jog forward or jog reverse user-supplied
input switches or by ladder diagram logic. An axis must be at rest
before a jog can be initiated. As long as the jog input is asserted, the
jog will continue at the specified rate.
Once released (off) the jog will decelerate to a zero rate over the time
defined by the decel value programmed in the jog move. If desired,
the final position value can serve as an upper (or lower) limit of jog
travel. The jog will automatically decelerate to reach a zero rate at
the programmed final position if the jog input is held on.
If the final position value of the jog is programmed as zero, the limit
of travel will be 999,999 pulses. If the decel value is programmed as
zero, the jog rate will cease instantly when the jog input is turned off.
!
ATTENTION: Avoid damage to the stepper motor
and machine by selecting jog final rate and decel
values which are compatible with the stepper
motor/machine dynamics.