Rockwell Automation DeviceNet Media Design Installation Guide - Manual (Page 92)

Publication DNET-UM072C-EN-P - July 2004
4-14 Determine Power Requirements
4. Add each device’s current together in section 1.
1.10+1.25+0.50 = 2.85A
5. Add each device’s current together in section 2.
0.25+0.25+0.25 = 0.75A
6. Find the value next largest to each section’s length using Figure 4.1 on
Page 4-4 to determine the approximate maximum current allowed for
each section.
Section 1 = 100m (2.93A)
Section 2 = 160m (1.89A)
Section 1 is operational since the total current does not exceed the maximum
current (2.85A < 2.93A).
Section 2 is operational since the total current does not exceed the maximum
current (0.75A < 1.89A).
power
supply
D1
PT T TR TR T T T T T
section 1
86 m
(282 ft)
55 m
(180 ft)
section 2
D2 D3 D4 D5 D6
1 m
(3 ft)
85 m
(279 ft)
127 m
(417 ft)
158 m
(518 ft)
1.10A 1.25A 0.50A 0.25A 0.25A 0.25A
TR = terminating resistor T = T-Port tap
PT = Power Tap D = device
31513-M
IMPORTANT
Section 1+ Section 2 < 3.6A. This is < 4A for
NEC/CECode compliance. However, if due to derating of
the power supply, you used a power supply larger than 4A,
you would exceed the NEC/CECode maximum allowable
current.
Results