Rockwell Automation DeviceNet Media Design Installation Guide - Manual (Page 96)

Publication DNET-UM072C-EN-P - July 2004
4-18 Determine Power Requirements
Two Power supplies (not end-connected) in parallel with no V+
break
The following example uses the look-up method to determine the
configuration for two power supplies that are not end-connected. This
configuration provides the most power to the cable system. You must use
diodes at the power taps to prevent back-feeding of the power supplies. Check
your national and local codes for any restrictions on the use of parallel power
supplies.
1. Determine the trunk line length of one end section (for this example we
will use section 3).
122m
2. Add each device’s current together in section 3.
0.25+1.00+0.30 = 1.55A
power
supply
D3
PT T TR TR T T T T T
section 1
244 m
(800 ft)
122 m
(400 ft)
section 2
D2 D1 D4 D5 D6
30 m
(100 ft)
60 m
(200 ft)
122 m
(400 ft)
244 m
(800 ft)
0.25A 0.25A 0.25A 0.25A 1.5A 0.5A
TR = terminating resistor T = T-Port tap
PT = Power Tap D = device
31515-M