DeviceNet Cable

Either DeviceNet thick cable or thin cable can be used.  Thick cable permits greater cable

lengths and higher current levels. Generally, thick cable is used for the trunk cable.  Thin cable

is normally used for shorter distances and is suitable for drop cables and for installations where

more cable flexibility is needed. Both thick cable and thin cable are 5-wire, multi-conductor

copper cable.  Two wires form a transmission line for network communications. A second pair

transmits network power.  The fifth conductor forms an electromagnetic shield. Most cables

have color coded leads which correspond to the color coding on the terminals on the DeviceNet

Master Module.

Power Requirements

The DeviceNet Master module consumes 450mA at 5VDC (typical) from the PLC backplane.

This power is used for module operation, The DeviceNet Master powers its network transceiver

from the 24VDC DeviceNet network power source. Linear power supplies are recommended for

the DeviceNet power source. The DeviceNet power source should not also be used for device

power. Transients caused by  I/O devices can cause communications errors and even create

bus-off conditions.

The DeviceNet specification recommends using a power tap to connect a power supply to the

network. The power tap should be appropriately fused for the current capacity of the bus cables.

The maximum current on the network depends on the cable type.

The DeviceNet network power supply must 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.