Rockwell Automation 1785-BCM_BEM, D17856.5.4 PLC-5 Backup Communication Module User Manual - Manual (Page 26)

Installing Your PLC-5 Backup System
Chapter 3
3-3
The logic circuit of the 1785-BCM module is driven by a power supply
through the backplane of the I/O chassis. Determine the power supply
requirements for your PLC-5 backup system:
1. Add these values to determine output current needed from the power
supply.
1.0A at 5V for a 1785-BCM module and
2.5A for the PLC-5/15 or PLC-5/25 processor or
3.3A for PLC-5/11, -5/20, -5/30, -5/40, -5/60, or -5/80 processor
2. Refer to Table 3.A to choose the power supply that provides
sufficient power for all modules in your backup system.
Important: Refer to Chapter 4 to select your power supply when you add
a 1785-BEM module in your backup system.
Table 3.A
Power Supplies for a PLC-5 Backup System
Power Supply Output Current (in amps) Power Supply Location
1771-P4 8 slot
1771-P4R 1 8 slot
1771-P4S 8 slot
1771-P4S1 8 slot
1771-P5 8 slot
1771-P6S 8 slot
1771-P6S1 8 slot
1771-P6R 8 slot
1771-P7 16 external 2
1771-PS7 16 external 2
1 A P4R redundant power supply can prevent system switchover due to power supply failures
or incoming power failures.
2 You cannot use an external power supply and a power supply module to power the same
chassis; they are not compatible.
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