Parker Automation Gemini GV6K, Command Reference Manual

Page: 143 / 362

Command Descriptions 141
Steppers only: An
FSHFC
move may be performed only when the follower is in the continuous
positioning mode (
MC1
) and performing a Following move at a constant ratio.
The most recently commanded velocity (
V
) and acceleration (
A
) for the follower axis will determine the
speed at which the
FSHFC
move takes place. The velocity and direction of the
FSHFC
shift is independently
superimposed on whatever velocity and direction results from the ratio and motion of the master. The
FSHFC
shift is not a change in ratio; rather, it is a velocity added to a ratio. The velocity commanded is
added to the present speed at which the follower is moving, up to the velocity limit of the product. For
example, assume a follower is traveling at 1 rps in the positive direction while following a master. If a
FSHFC
move is commanded in the positive direction at 2 rps, the follower's actual velocity (after
acceleration) will be 3 rps.
The
FSHFC
parameters stop (
Ø
) and kill (
3
) can be used to halt a continuous
FSHFC
move (positive-
direction or negative-direction). The example below shows how to stop a
FSHFC
continuous move.
An
FSHFC
move may be needed to adjust the relative follower position on the fly during the continuous
Following move. For example, suppose an operator is visually inspecting the follower's motion with respect
to the master. If he notices that the master and follower are out of synchronization, it may be desirable to
have an interrupt programmed (e.g., activated with a push-button switch) that will allow the operator to
advance or retard the follower at a superimposed correction speed until the operator chooses to have the
follower start tracking the master again. The example below shows this.
FSHFC
Example:
Assume all scale factors and set-up parameters have been entered for the master and follower. In this
example, the follower is continually following the master at a 1:1 ratio. If the operator notices some
misalignment between master and follower, he can press 1 of 2 pushbuttons (connected to onboard trigger
inputs #1 and #2, which are also referred to as TRG-1A and TRG-1B) to shift the follower in the positive-
or negative-direction at 0.1 user scaled units until the button is released. After the adjustment, the program
continues on as before.
Example:
DEF SHIFT ; Begin definition of program called SHIFT
V.1 ; Add or subtract 0.1 user scaled units from the follower velocity
; when shifting
COMEXS1 ; Continue command execution after stop
COMEXC1 ; Continue command execution during motion
FOLMAS1 ; Master encoder input is the master
FOLRN1 ; Set follower-to-master Following ratio numerator to 1
FOLRD1 ; Set follower-to-master Following ratio denominator to 1
; (ratio set to 1:1)
FOLEN1 ; Enable Following mode
D+ ; Set to positive-direction
MC1 ; Select continuous positioning mode
GO1 ; Start following master continuously
VARB1=b10 ; Define onboard input pattern #1 and assign to VARB1
VARB2=b01 ; Define onboard input pattern #2 and assign to VARB2
$TESTIN ; Define label called TESTIN
IF(IN=VARB1) ; IF statement (if onboard input #1 is activated, do the jump)
JUMP SHIFTP ; Jump to shift follower in the positive-direction when pattern 1
; active
NIF ; End of IF statement
IF(IN=VARB2) ; IF statement (if onboard input #2 is activated, do the jump)
JUMP SHIFTN ; Jump to shift follower in the negative-direction when pattern 2
; active
NIF ; End of IF statement
JUMP TESTIN ; Return to main program loop
$SHIFTP ; Define label called SHIFTP (subroutine to shift in the
; positive direction)
FSHFC1 ; Start continuous follower shift move in positive-direction
WAIT(IN.1=b0) ; Continue shift until onboard input #1 is deactivated
FSHFC0 ; Stop shift move
JUMP TESTIN ; Return to main program loop
$SHIFTN ; Define label called SHIFTN (subroutine to shift in the
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