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3.5 Network Power/Grounding
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3.5 Network Power/Grounding
In a DeviceNet network, the power for communication (24 VDC) is supplied through the
DeviceNet power cables (V+/V-) via the network connector. This section describes
network power supply to the DeviceNet cables and network power configuration.
Grounding the network is also explained.
3.5.1 Network power supply method
In order to supply the network power (24 VDC) to the DeviceNet cables, the power tap
(Figure 3-8) specified for the DeviceNet must to be used. The power tap is an apparatus
for connecting a 24 VDC power unit to a trunk cable. It has the following functions:
(1) To prevent reverse current flow to two or more 24 VDC power units, if connected to
one network, due to potential difference
(2) To support a maximum of 16 A from the power units directly connected to the tap
(3) To limit the current flow from the power tap to the cables to 8 A maximum with a
protective circuit (fuse or circuit breaker)
(4) To provide terminals for grounding the network.
Figure 3-8 Power Tap Composition
Power Tap Composition
Model 1485T-P2T5-T5 (PowerTap)
Manufacturer Rockwell Automation
Power tap
V
−
V +
Schottky
diode
Protective
circuit
Protective
circuit
Network power unit
Maximum cable length from
power unit to power tap is 3 m.
Grounding terminal
DeviceNet cable
Trunk cable
Signal CAN_H
Signal CAN_L
V +
V
−
Shield/drain
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