DeviceNet

DeviceNet is a CAN-based industrial fieldbus that runs the Common Industrial Protocol (CIP) over CAN 2.0A. ODVA-managed and once the workhorse low-end network in the Rockwell ecosystem, it has been largely succeeded by EtherNet/IP for new builds but remains widely deployed.

Overview

• Multi-drop; up to 64 nodes per network.
• Carries data + 24 VDC power on a single 5-wire cable.
• Producer/consumer model — natural multicast on the CAN bus.
• Same CIP object model as EtherNet/IP & ControlNet.

Physical Layer

• 5-wire cable: V+, V−, CAN_H, CAN_L, drain (shield).
• Round (thick / thin) or flat KwikLink cable.
• 120 Ω terminators at both ends of the trunk.
• Power supply tap on the network; some segments use dual supplies.

Addressing & Baud

• Node addresses (MAC IDs) 0–63; default 63 for new devices.
• Baud / max length: 125 kbps / 500 m, 250 kbps / 250 m, 500 kbps / 100 m.
• All nodes must use the same baud; auto-baud devices exist but pin them in production.

Messaging

• I/O messaging — implicit, time-critical: polled, change-of-state, cyclic, strobed.
• Explicit messaging — config / diagnostics; non-real-time.
• Predefined Master/Slave Connection Set simplifies common use.

Configuration

• Use RSNetWorx for DeviceNet (now FactoryTalk Linx Network Browser) for design & commissioning.
• Load EDS files for each device.
• Build a scanlist on the scanner module (e.g. 1756-DNB).
• Map device assemblies into the scanner I/O image.

Troubleshooting

• Check 24 V power at the device drop.
• Measure termination — ~60 Ω across CAN_H / CAN_L with bus powered off.
• Duplicate MAC ID is the most common bring-up issue.
• Scanner LED steady green = healthy; flashing = node fault; check the node-fault table.
• Increase trunk wire gauge or add a second power supply if voltage drop is excessive.