Rockwell Automation 1400-SP PowerMonitor Software - Manual (Page 73)

Appendix B
Communications Application Note
B–5
Figure B–2
RS–485 Loop Topology
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RS–485 Terminals
+ – SHLD
RS–485 Terminals
+ – SHLD + – SHLD
Device #1
Device #2 Device #3
RS–485 Terminals
RS–485 Cable:
22 gauge shielded
twisted pair
IBM PC
RS–232C/RS–485
Converter
RS–232C
+ – SHLD
RS–485 Terminals
+ – SHLD
Device #1
Loop Topology
Loop topology also allows up to 32 devices to be connected along the 4000
foot length of the cable.
One advantage of the loop topology is that a single open circuit fault
condition on the main loop will not result in the loss of communication
between the computer station and any of the Powermonitors (see Figure
B–2).