Rockwell Automation 1785-BCM_BEM, D17856.5.4 PLC-5 Backup Communication Module User Manual - Manual (Page 49)

Installing Your 1785-BEM Module
Chapter 4
4-6
Switch Assembly
The 1785-BEM module has a switch assembly which specifies if Channels
2A and 2B are going to establish communication with Data Highway Plus
network or with the remote I/O link. When the module establishes
communication with the remote I/O link, the switch also determines the
baud rate and the mode of operation of the processor (scanner or adapter).
To set these switches, refer to the section on “Setting the Switch
Assembly.”
I/O Backplane Interface
The 1785-BEM module communicates with the 1785-BCM module
through its connection with the I/O chassis backplane.
The logic circuit of the 1785-BEM module is driven by the power supply
through the backplane of the I/O chassis. Use the following guidelines to
determine the power supply requirements for your PLC-5 backup system.
1. Add these values to determine output current needed from the power
supply for all the modules in that chassis.
0.6A at 5V for the 1785-BEM module and
1.0A at 5V for the 1785-BCM module and
3.3A for the PLC-5/40 or PLC-5/60 processor
2. Refer to table 3.A, Power Supplies for a PLC-5 Backup System, to
select your power supply.
3. Use separate power sources for the primary and secondary
processors. Connect the power supplies through different power
sources to take precautions against interruptions and incoming power
failures.
Determining Power Supply
Requirements