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Chapter 2. Installation
2.3
2.3.1
Grounding
DeviceNet Cable Grounding
All DeviceNet cable shields must be tied to ground at each device connection. This is done by tying the bare
wire of the cable to pin 3 (Shield) of the connector.
2.3.2
DeviceNet Power Supply Grounding
The DeviceNet network power supply must also be grounded, but only at one point. The V- signal must be
connected to protective earth ground at the power supply only. If multiple power supplies are used, only one
power supply must have V- connected to earth ground.
2.3.3
DeviceNet System Grounding
DeviceNet communications should only be grounded to earth at a single point. Typically this is done in the
control cabinet where the DeviceNet power supply is located.
Return for the DeviceNet power (-V), the drain (bare wire) and the cable shields must be directly tied to earth
ground. Ideally, this grounding is done at a central location. Connection should be made using a 25mm (1in.)
copper braid or a #8 AWG wire not longer than 3meters (10ft.).
The illustration below represents grounding for a network that has two power supplies. The chassis of each
power supply is connected to earth ground.
Power Supply #1
Return
+24V
Power Supply #2
Return
+24V
V+
CAN_H
SHIELD
CAN_L
V-
Figure 8: Grounding Example
Ground Wire Size
The minimum size ground conductor for the DeviceNet screw-clamp terminals on a DeviceNet module is a
2.5mm2 (14 AWG) wire. For other network devices, larger wire diameters may be necessary.
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DeviceNet Modules for PACSystems* RX3i and Series 90*-30 User's Manual
GFK-2196B