Rockwell Automation GMLC Reference Manual - Manual (Page 329)

Publication GMLC-5.2 - November 1999
292 I/O and Event Blocks
When you enable an output cam, the selected discrete output is no longer
available for use in an Output block. When you disable an output cam, the
output again becomes available for use in an Output block as a standard
discrete output. Until the discrete output is re-used, and given a new value
by the application program, it retains its current value.
A typical mechanical output cam consists of a shaft geared 1:1 with the
machine such that it rotates exactly one revolution per machine cycle.
Attached to this shaft are many individual cam wheels with cutouts that
are read by proximity switches whose outputs are used to activate
solenoids, valves, etc., as shown below.
The Output Cam block simulates this operation using a discrete output.
Up to 48 output cams can be configured using Flex I/O outputs, general
purpose outputs, RIO discrete outputs, or SLC output bits. Generally,
when the position of the selected axis is within the window defined by the
start of window and end of window positions, the output is on; otherwise,
it is off.
!
ATTENTION: If a discrete output is configured as an
output cam, do not use an Output block to turn that
discrete output on or off.
Proximity Switches
Cam Wheels
Drive Shaft
(rotates with
machine)
To solenoids,
valves, etc.