WAGO 750-306 Technical Description

Also see for DeviceNet 750-306: Manual

WAGO 750-306 Technical Description Manual pdf 112 page image

112 ï DeviceNetNetwork CommunicationWAGO-I/O-SYSTEM 750DeviceNet5.3 Network Communication5.3.1 Objects, Classes, Instances and AttributesProtocol processing of DeviceNet is object oriented. Each node in the networkis represented as a collection of objects. In the following, several terms con-nected with them are defined:• Object:Object is an abstract representation of individual components within a de-vice belonging to each other. It is defined by its data or attributes, its ex-ternal functions or services available, and by its defined behaviour.• Class:A class includes objects of a product belonging together, it is organized ininstances, e.g. Identity Class, DeviceNet Class.• Instance:An instance is composed of various variables (attributes). Differing in-stances of a class have the same services, the same behaviour and the samevariables (attributes). However, they can have different variable values,e.g. different connection instances: Expilict Message, Poll I/O or Bit-Strobe connection instance.• Attributes:The attributes represent data provided by a device via DeviceNet. Theycontain the current values, e.g. a configuration of an input, such as, for in-stance Vendor ID, Device Type or Product Name.• Service:Services can be applied to classes and attributes. They perform defined ac-tions, e.g. reading of variables (attributes) or resetting a class.• Behaviour:The behaviour defines how a device reacts as a consequence of externalevents, such as changed process data, or as a consequence of internalevents, such as expiring timers.