Rockwell Automation 1775-S5_SR5,D17756.5.5 User Manual PLC-3 FAMILY I/0 - Manual (Page 20)

Scanner Hardware and Installation
Chapter 1
1-11
The chassis electromechanically interlocks helping to guard against
inserting or removing modules while power is on.
ATTENTION: Do not change the thumbwheel setting on a
scanner while power is on. This could result in equipment
damage.
PLC-3 and PLC-3/10 systems require a scanner with the thumbwheel set
to 1. If you are using a multi-chassis system, the scanner set to 1 must be
in the chassis with the front panel.
You can operate a 1775-S5 scanner with a 1775-S4A, -S4B scanner in a
PLC-3 system and a 1775-SR5 with a 1775-SR scanner in a PLC-3/10
system. However, note the following cautions.
ATTENTION: You can replace a 1775-S4A, -SR scanner with
a 1775-S5, -SR5 scanner, however, you must:
perform a logical save of memory without saving the module
status area (E2)
clear memory after replacing one scanner with another.
restore the previously stored memory
configure each 1775-S5, -SR5 scanner communication
channel in LIST.
Failure to observe this caution could result in equipment
damage and/or undesired machine operation.