Rockwell Automation 8520 9/Series CNC Integration Maintenance Manual Documentation Set - Manual (Page 528)

I/O Interface
Section 10A
10A-5
The devices on the fiber optic I/O ring convert electrical signals to optical
signals for transmission through the I/O ring. These optical signals are
converted back to electrical signals at the sub processor board for use by
the PAL program. An example of the input process is shown in
Figure 10A.2.
Figure 10A.2
PAL Fiber Optic Input Process
Executing PAL checks for %HOM_SW1 input
to be true prior to setting $HMSW.00 true
I/O signals
converted
from optical
to electrical
Other
I/O ring
devices
I/O signals converted
from electrical to optical
I/O name %HOM_SW1
assigned to input labeled
A08 on I/O device
Home Switch
(typical I/O
input element)
Customer
supplied I/O
power source
11387-I
1746 I/O Rack