Rockwell Automation 1772-LP3 PLC - 2/30 Programmable Controller Programming and Operations Manual - Manual (Page 151)

Output Override and I/O Update Instructions
Chapter 7
7Ć9
The remote fault zone programming technique is used to disable parts of or
the entire user program when a fault occurs in a remote I/O rack. Remote
I/O racks are controlled by the processor via the 1772-SD2 distribution
panel and can be located up to 10,000 feet from the panel. Up to two local
I/O racks can be used with remote I/O racks in a system (Figure 7.5).
Unlike local I/O racks, each remote I/O rack can have up to 128 I/O points
using one of the following arrangements:
One 128-I/O chassis
Two 64-I/O chassis
One 64-I/O chassis and two 32-I/O chassis
Four 32-I/O chassis
The PLC-2/30 can control up to 14 I/O racks when using the 1772-SD2
distribution panel. For information on wiring, switch settings and use of
the 1772-SD2 distribution panel, refer to the Allen-Bradley Remote I/O
Scanner/Distribution Panel Product Data (publication no. 1772-929).
7.4
Remote Fault Zone
Programming