Rockwell Automation 8520 9/Series CNC Integration Maintenance Manual Documentation Set - Manual (Page 529)

I/O Interface
Section 10A
10A-6
This entire process is reversed for outputs originating from the PAL
program. An example of the output process is shown in Figure 10A.3.
Figure 10A.3
PAL Fiber Optic Output Process
PAL signals converted
from optical to electrical
I/O name %ES_ALARM
assigned to output labeled
B12 on I/O device
E-Stop Warning Alarm
(typical I/O output element)
PAL signals
converted from
electrical to optical
Executing PAL checks $ESTOP
(from the control) and sets %ES_ALARM true
Customer
supplied I/O
power source
Other I/O
ring devices
1746 I/O Rack
All I/O devices on the I/O ring must be assigned a position that
corresponds to the physical location of that device on the I/O ring. Their
corresponding input and output terminals must be assigned variable names.
These assignments are listed in the I/O Assignment file.