Electro Cam PS-6144 Series - Manual (Page 44)

3-16 Programming
Offset
Menu Path MAIN SCREEN to SETUP MENU to OFFSET
Background Because the PS-6144 is a programmable device, it can be set to display a position of
“zero” at any point in the machine cycle. Usually, a machine is jogged to the beginning
of a cycle, and the SHAFT POSITION function is set to zero at this point.
In addition, each output group operating in Mode 0, 3, 4, or 5 can be individually “offset”
from this SHAFT POSITION through OFFSET programming. This allows the output
channels in a group to be set to “zero” at a different machine position than the one that
corresponds to “zero” in SHAFT POSITION.
Note: When programming a controller, there must be more than one group defined in
the CONFIG MENU in order fro a user to adjust OFFSET for a group in the SETUP
MENU.
Setting a group to its own zero position can simplify setpoint programming for output
channels by clarifying the relationship between the setpoints and the machine compo-
nent controlled by the group. For example, suppose that an output group controls a
glue head on a cartoning machine. By jogging the machine and viewing POS on the
PS-6144 display, you realize that the glue head must turn on at 347
°
and off at 22
°
when using the position set through SHAFT POSITION. Since other output channels
correlate well with SHAFT POSITION, you don’t want to change it. Instead, using the
OFFSET function for this group, you could add 13
°
to the shaft position so that the glue
head would turn on at a group position of 0
°
and off at 35
°
. Although the group posi-
tion has been “offset” by 13
°
, the gun would still turn on at 347
°
and off at 22
°
in terms
of shaft position.
For output groups operating in Mode 1 or 2, the group position is reset to a “preset”
value whenever the group’s input terminal is energized. This preset is defined through
OFFSET programming. Because the reset can occur at any resolver position, the rela-
tionship between the position of a group operating in Mode 1 or 2 and the SHAFT
POSITION varies.
Units with the gray code output option “-G” generate an 8-bit position signal across
Outputs 1 through 8. This gray code position signal always corresponds to the position
as programmed through SHAFT POSITION, and is not affected by group positions
programmed through the OFFSET function.
Screens OFFSET Screen—Group Mode 0, 3, 4 or 5
OFFSET Screen—Group Mode 1 or 2
(continued)
GRP:1< POS: 0
ABS: 132
Group Position = Shaft Position + ABS Offset
Absolute Offset Value for this Group
Output Group
GRP:1< POS: 359
PRE: 30
Group Position = PRE + Change Since Last Reset
Group Preset Value (If Group is Mode 1 or Mode 2)
Output Group