DeviceNet fieldbus network - technology overview

The Device Level Network

DeviceNet was originally developed by Rockwell Automation and today, It is managed by the Open Devicenet User organization (ODVA). Devicenet is among the worlds leading device level networks for industrial automation. DeviceNet is a very popular network for time critical applications based on Rockwell Automation technology. DeviceNet offers robust, efficient data handling because it is based on Producer/Consumer model. DeviceNet is standardized in the international standard series IEC 61158. DeviceNet devices are certified for interoperability and conformance to the DeviceNet standard by ODVA.

Provider/Consumer Communication
DeviceNet is a digital, multi-drop network that connects and serves as a communication network between industrial controllers and I/O devices. Each device and/or controller is a node on the network. DeviceNet is a producer-consumer network that supports multiple communication hierarchies and message prioritization. DeviceNet systems can be configured to operate in a master-slave or a distributed control architecture using peer-to-peer communication. DeviceNet systems offer a single point of connection for configuration and control by supporting both I/O and explicit messaging. DeviceNet also has the unique feature of having power on the network. This allows devices with limited power requirements to be powered directly from the network, reducing connection points and physical size.

DeviceNet uses a trunk-line/drop-line topology that provides separate wire pairs for both signal and power distribution. Thick or thin cable can be used for either trunklines or droplines. End-to-end network length varies with data rate and cable thickness.

DeviceNet uses the Common Industrial Protocol, called CIP, for its upper protocol layers. CIP is strictly object oriented. Each object has attributes (data) and services (commands) and behavior (reaction to events). Two different types of objects are defined in the CIP specification: communication objects and application-specific objects. Vendor-specific objects can also be defined by product vendors for situations where a product requires functionality that is not in the specification.

Configuration with EDS-Files
During the setup phase of the DeviceNet network, the DeviceNet Master Scanner must be configured with a special configuration tool such as Rockwell's RSNetWorx or HMS´s NetTool. The configuration process is based on electronic device data sheets (EDS-Files) which are required for each DeviceNet device. EDS-Files are provided by the device manufacturers and contain electronic descriptions all relevant communication parameter and objects of the DeviceNet device.

DEVICENET FACTS
Network Type:	CAN-based Producer/Consumer Fieldbus communication system
Topology:	Bus line with trunkline/dropline topology
Installation:	- Shielded cable with 2 pairs of 2 wires each - Cable contains data and 24 Volt bus power on separate wires - Connection via pluggable screw terminals or M12 connectors - Segment length depending on cable and baudrate 100 - 500m
Speed:	125 - 500 kbit/s
max. Stations :	64
Data :	- max. 8 Byte per telegram frame - larger data packages require segmentation
Network Features :	Field level communication system of the CIP network family, providing advanced communication features for field devices
User Organization:	Open DeviceNet Vendors Organization (ODVA)

HMS is an active member of the DeviceNet User Organization and participates actively in the further standardization of the DeviceNet technology. HMS offers a broad range of certified DeviceNet products.