Gemini GV6K and Gemini GT6K Programmer's Guide

FSHFD Example
In this example, the follower follows a master that moves in a continuous cycle. Once each
cycle, the master and follower both pick parts. The master’s part is detected by a sensor
connected to trigger 1B, and the follower’s part is detected by a sensor connected to trigger 1A.
After both parts are detected, they must be aligned. The sensors are mounted 2 inches apart
from each other, so that proper alignment would result in 2 inches of follower travel between
detection of the master's part and detection of the follower’s part.
The follower position is sampled when each of the sensors activates. The difference between
the follower positions is compared to the required 2 inches. If the measured difference is
greater than or less than 2 inches, then a shift move to correct the alignment is made. At that
point, the follower will then start tracking the master again. The follower is continually
following the master at a 1:1 ratio.
DEL ALIGN
; Delete program before defining
DEF ALIGN
; Begin definition of program called ALIGN
COMEXC1
; Allow continuous command execution during motion
FOLMAS1
; The master encoder input is the master
FOLRN1 ; Set follower-to-master ratio numerator to 1
FOLRD1 ; Set follower-to-master ratio denominator to 1
; (ratio set to 1:1)
FOLEN1
; Enable Following mode
MC1
; Enable continuous positioning mode
D+ ; Set direction to positive
GO1
; Start Following master continually
INFNC1-H
; Enable trigger input 1A to latch position of follower
; when the follower's part is detected
INFNC2-H
; Enable trigger input 1B to latch position of follower
; when the master's part is detected
$SYNCLP
; Main loop where synchronizing moves occur
WAIT(TRIG.1=b1 AND TRIG.2=b1)
; Wait for both follower and master inputs to occur
VAR10=1PCCA ; Load VAR10 with the follower commanded position due
; to follower input activation
VAR11=1PCCB ; Load VAR11 with the follower commanded position due
; to master input activation
VAR12=VAR10-VAR11 ; Load VAR12 with the offset distance
VAR13=VAR12-2 ; Calculate the required shift
FSHFD(VAR13) ; Perform synchronization move of distance in VAR13
JUMP SYNCLP ; Return (jump) to main program loop
END
; End of program
Geared Advance Following
The FGADV command provides the ability to super-impose an advance or retard on Following
motion. This is the same ability provided by the FSHFD command (see Performing Phase
Shifts above), except that the super-imposed motion is also geared to master motion. The
FGADV command has the positive or negative “advance” distance as a parameter, but it
initiates motion instead of simply setting up the distance. The shape of the super-imposed
profile is determined by the FOLMD, FOLRN, and FOLRD commands (just as a normal preset
Following move).
The FGADV command profile may be delayed with the GOWHEN command.
A FGADV move may be performed only while the conditions below exist (Following status bit
#23, reported with the FS, TFS, and TFSF commands, indicates that it is “OK to do FGADV
move”):
• Master is specified with a FOLMAS command
• Following is enabled with the FOLEN command
• The follower is either not moving, or moving at constant ratio in continuous mode
(MC1)
180 Gem6K Series Programmer’s Guide