Rockwell Automation 1785-BCM_BEM, D17856.5.4 PLC-5 Backup Communication Module User Manual - Manual (Page 21)

Understanding the 1785-BCM
Hardware Components
Chapter 2
2-5
Figure 2.3
Relays for Processor A and Processor B
PLC-5
HSSL
PLC-5
Remote I/O
DH+
PLC-5
HSSL
PLC-5
Remote I/O
DH+
Customer
Relay
Customer
Relay
1785-BCM 1785-BCM
1785-BCM 1785-BCM
Processor A (primary)
Processor B (primary) Processor A (secondary)
Processor B (secondary)
11051I
Important: When using a 1785-BCM module with a PLC-5/40, PLC-5/60,
or PLC-5/80 processor, you can add a 1785-BEM backup expansion
module to provide backup for all processor communication channels. The
channels of the 1785-BEM module, like the 1785-BCM module, can be
configured for Data Highway Plus or remote I/O. For more information on
the 1785-BEM backup expansion module, refer to Chapter 4.
The customer relay connection on the 1785-BCM module is used to switch
external devices. Relay contacts are rated at .25A @ 24V dc resistive.
Loads with inductive characteristics will require additional suppression
devices. Customer Relay