Rockwell Automation 1785-LTx,D17856.2.1 Classic PLC-5 Programmable Controllers Users Manual - Manual (Page 33)

Choosing Hardware
Chapter 2
2-14
Use the following modules in either primary or complementary I/O chassis
opposite any type of module:
Communication Adapter Module (1771-KA2)
Communication Controller Module (1771-KE)
PLC-2 Family/RS-232-C Interface Module (1771-KG)
Fiber Optics Converter Module (1771-AF)
DH/DH+ Communication Adapter Module (1785-KA)
DH+/RS-232C Communications Interface Module (1785-KE)
Use the following modules in either primary or complementary I/O chassis
opposite any type of module. However, these modules do not work as
standalone modules; each one has an associated master module. Use care
when placing the master modules in the I/O chassis (refer to the paragraph
on Master/Expander I/O modules):
Analog Input Expander Module (1771-E1, -E2, -E3)
Analog Output Expander Module (1771-E4)
Servo (Encoder Feedback) Expander Module (1771-ES)
Pulse Output Expander Module (1771-OJ)
A PLC-5 processor backup system contains two of each of the following
hardware components:
Classic PLC-5 processor module
Processor Catalog Number
PLCĆ5/15 1785ĆLT Series B
PLCĆ5/25 1785ĆLT2
1785-BCM Series C Backup Control Module (for 2 channels)
1785-BEM Backup Expansion Module (for 2 additional channels)
Power supply
Local chassis
Important: The PLC-5 backup system does not back up I/O in the
processor-resident local chassis. Do not install I/O in the processor-
resident local chassis of a backed up system.
Refer to the PLC-5 Backup Communication Module User Manual,
publication 1785-6.5.4, for more information on configuring a PLC-5
processor backup system.
Selecting a PLCĆ5 Processor
Backup System