Chapter 8: DeviceNet The basic topology is the trunkline-dropline topology. This topology uses separate twisted-pair buses for the distribution of signals and power. The specifications allow trunk lines and drop lines made of thick or thin cable. The baud rate, maximum distance from end-to-end of the net- work, and cable size are dependent on each other. See the table Features of a DeviceNet Net- work on page 85 for further details. Figure 8-1. Trunk Lines and Drop Lines Made of Thick and Thin Cable DeviceNet allows devices to be powered directly from the bus, and devices can use the same cable to communicate with other devices on the bus.
DeviceNet nodes are hot-pluggable — you can remove or add components on the bus without powering down the network. NOTE : This hot-pluggable feature requires the configuration of the controller to match the configuration of the physical network. The default configuration auto- matically recognizes and maps the first 64 bits of Mac ID 1 and 2. If the con- figuration needs to be changed, use ACE Configuration Tools. The power distribution on the network/bus does not need to be in one place. The distribution of power supplies needs to be well-planned because there are certain constraints on the power supply. In general, power supplies can be placed at any point in the network.
The maximum current rating of a trunk line is 8 amps. DeviceNet allows opto-isolated, externally powered devices (e.g., AC drive starters and solenoid valves) to operate on the same bus cable. For detailed information, see the DeviceNet Technical Specifications. SmartController EX User’s Guide, 11069-000 Rev. F Page 84 of 92