Rockwell Automation 8520 9/Series CNC Integration Maintenance Manual Documentation Set - Manual (Page 527)

I/O Interface
Section 10A
10A-4
I/O devices are connected either directly to the control or through a fiber
optic I/O ring that provides serial communication with the control. The
I/O devices on the 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. This entire process is reversed for outputs originating from the
PAL program.
Each I/O device connected to the I/O ring has an transmitter and receiver.
Fiber optic cables connect transmitters to receivers to form the I/O ring. A
typical ring layout is shown below.
Figure 10A.1
Typical Layout of a Multiple Device Fiber Optic I/O Ring
HPG
9/290 Processor
1746 I/O Rack
High--density I/O
Digital I/O
MTB Panel
Operator’s Panel
11386-I
10A.1
Fiber Optics