Rockwell Automation DeviceNet Media Design Installation Guide - Manual (Page 30)

Publication DNET-UM072C-EN-P - July 2004
1-20 Get Started
The following example uses the look-up method to determine the configuration
for one end-connected power supply. One end-connected power supply
provides as much as 8A near the power supply.
1. Determine the total length of the network.
106m
2. Add each device’s current together to find the total current
consumption.
0.10 + 0.15+ 0.30 + 0.10 = 0.65A
3. Find the next largest network length using the table on page 1-19 to
determine the approximate maximum current allowed for the system.
120m (2.47A)
Since the total current does not exceed the maximum allowable current, the
system will operate properly (0.65A
≤ 2.47A).
power
supply
TR TR PT T T T
D1 D2 D3 D4
0.10A 0.15A 0.30A 0.10A
23m
(75 ft)
30m
(100 ft)
53m
(175 ft)
106m
(350 ft)
TR = terminating resistor T = T-Port tap
PT = PowerTap tap D = device
T
41833
IMPORTANT
Make sure that the required power is less than the rating of
the power supply. You may need to derate the supply if it is
in an enclosure.
IMPORTANT
If your application doesn’t fit “under the curve,” you may
either:
• Do the full-calculation method described in Chapter 4.
• Move the power supply to somewhere in the middle of
the cable system and reevaluate as described in the
previous section.
Results