GE Motor Protection System A.1.8 DeviceNet Specification Highlights, Description, Connections

DEVICENET OVERVIEWCHAPTER A:

Table A–1: Trunk Cable Length Specification

Baud rate	100% thick cable	100% thin cable	Flat cable
125 kbps	500 meters	100 meters	420 meters
250 kbps	250 meters	100 meters	200 meters
500 kbps	100 meters	100 meters	100 meters

Table A–2: Drop Cable Length Specification

Baud rate	Maximum	Cumulative
125 kbps	6 meters	156 meters
250 kbps	6 meters	78 meters
500 kbps	6 meters	39 meters

A.1.8 DeviceNet Specification Highlights

Description:

The DeviceNet specification defines a network communication system for transferring data between elements of an industrial control and automation system. The specification is divided into two volumes and defines the following elements:

Volume 1:

•DeviceNet communication protocol and application (Layer 7: Application layer)

•CAN and its use in DeviceNet (Layer 2: Data Link Layer)

•DeviceNet physical layer and media (Layer 1: Physical Layer)

•Volume 2:

•Device profiles for interoperability and interchangeability among like products

CAN defines the syntax or form of the data transfer. The DeviceNet application layer defines the semantics or meaning of the data transferred

Communication Protocol and Application:

Standard or application specific objects are combined together into Device Profiles by the applications using DeviceNet. The Device Profile defines the device as viewed from the network: DeviceNet specifications contains a library of objects and Device Profiles. ODVA coordinates the work of industry experts in the development of both new Object and Device Profile specifications.

DeviceNet supports strobed, polled, cyclic, change-of-state, and application-triggered data transfer. The user can choose master/ slave, multi-master and peer-to-peer, or a combination depending on device capability and application requirements. The choice of data transfer can significantly speed up system response time. One popular application for DeviceNet is to use a standard, predefined set of connections that allow devices to operate in a master/slave connection set.

Connections:

The DeviceNet communication protocol is based on the idea of connections. Connections must be established with a device in order to exchange information with that device.

A–4 LM10 MOTOR PROTECTION SYSTEM – INSTRUCTION MANUAL