DeviceNet Protocol

DeviceNet is an industrial automation protocol developed by Rockwell Automation, built on the Controller Area Network (CAN) technology. It is widely used for communication between industrial controllers and I/O devices, such as sensors, actuators, and drives. DeviceNet simplifies wiring, reduces installation costs, and enhances data exchange between devices.

Overview of DeviceNet Protocol

DeviceNet provides a robust communication network that supports real-time data exchange and control in industrial automation systems. It uses a multi-drop network topology, allowing multiple devices to connect on a single network segment.

Key Features of DeviceNet

• Based on CAN Technology: Utilizes the reliable CAN protocol for communication.
• Multi-Drop Network Topology: Supports connecting multiple devices on a single network segment.
• Device Profiles: Defines standard device profiles for interoperability between devices from different manufacturers.
• Power and Data on the Same Cable: Combines power and data signals on the same cable, reducing wiring complexity.
• Flexible Network Configuration: Supports a variety of network configurations and topologies.

How DeviceNet Works

DeviceNet operates on a physical layer based on the CAN protocol, using a five-wire cable for communication. The five wires include two for data (CAN_H and CAN_L), two for power (V+ and V-), and one for shielding (SHIELD).

DeviceNet Communication Layers

• Physical Layer: Defines the physical connections and signal characteristics.
• Data Link Layer: Manages data transfer between devices using CAN technology.
• Application Layer: Defines the structure and meaning of messages exchanged between devices.

DeviceNet Pinout

DeviceNet uses a 5-pin open-style connector for communication:

• Pin 1: Shield (SHIELD)
• Pin 2: V+ (Power Supply +24V)
• Pin 3: V- (Power Supply 0V)
• Pin 4: CAN_H (CAN High Data Line)
• Pin 5: CAN_L (CAN Low Data Line)

Example: Connecting Devices via DeviceNet

To connect devices using DeviceNet, follow these steps:

1. Connect the SHIELD wire to Pin 1 of each device.
2. Connect the V+ wire to Pin 2 of each device to provide power.
3. Connect the V- wire to Pin 3 of each device to complete the power circuit.
4. Connect the CAN_H wire to Pin 4 of each device for the CAN High data line.
5. Connect the CAN_L wire to Pin 5 of each device for the CAN Low data line.
6. Ensure proper network termination at both ends of the network segment.

DeviceNet Messaging

DeviceNet supports various types of messages for different purposes, including explicit messages for configuration and implicit messages for real-time data exchange.

Explicit Messages

Explicit messages are used for device configuration, diagnostics, and non-time-critical data exchange. They follow a request/response model.

Implicit Messages

Implicit messages are used for real-time data exchange between devices. They are typically cyclic and event-driven, ensuring timely data updates.