DeviceNet • 113

Module Characteristics

5.4 Module Characteristics

The I/O module is defined by vendor ID and device type.

5.4.1 Communication Model

5.4.1.1 Message Groups

CAN messages are divided into several groups in order to achieve different priorities.

•message group 1 serves to exchange I/O data via I/O messages

•message group 2 is reserved for Master/Slave applications

•message group 3 serves to exchange configurations data via explicit messages

•message group 4 is reserved for system administration (i. e. Offline Connection Set)

The CAN Identifier (Connection ID) and with it the priority is built via different message groups and the MAC ID.

5.4.1.2 Message Types

DeviceNet has 2 types of messages:

•I/O Messages and

•Explicite Messages

5.4.1.2.1I/O Messaging

I/O messages are sent by a node and can be received by one or several other nodes. Only I/O data is transmitted and no protocol data is specified by this way.

5.4.1.2.2 Explicit Messaging

Explicit messages are sent directly from one node to another. They consist of a request and an answer. Therefore services can be requested directly from another node. The data field consists of the service identification and the destination address. The format of the explicit messages is defined. Via explicit messages devices can be configured or a dynamic built-up of message connections can be made.

WAGO-I/O-SYSTEM 750

DeviceNet