VIPA System 200V IM Series, Руководство пользователя

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Manual VIPA System 200V
Chapter 6 DeviceNet
HB97E - IM - Rev. 06/29 6-3
Basics
DeviceNet is an open low-end network that is based upon the physical
properties of CAN-Bus. The bus is also used to supply the devices with the
required DC 24V power.
You can use DeviceNet to install direct connections between your control
system and simple industrial devices like sensors and switches as well as
technologically advanced devices like frequency converters and barcode
readers.
Direct interfacing improves communications between the different devices
and provides important diagnostic facilities at the device level.
DeviceNet is an open device net standard that satisfies the user profile for
industrial real-time system applications.
The DeviceNet protocol has an open specification that is the property of
and administered by the independent vendor organization "Open
DeviceNet Vendor Association" ODVA.
This is where standardized device profiles are created to provide
compatibility and exchangeability on logical level for simple devices of the
same type.
In contrast to the classical source–destination model, DeviceNet uses a
modern producer/consumer model that requires data packets with identifier
fields for the identification of the data.
This approach caters for multiple priority levels, more efficient transfers of
I/O data and multiple consumers for the data.
A device that has data to send
produces
the data on the network together
with an identifier. All devices requiring data listen for messages. When a
device recognizes a suitable identifier, they act and
consume
the respec-
tive data.
DeviceNet carries two types of messages:
•
I/O messages
Messages that are subject to critical timing constraints and that are
contain data for control purposes that can be exchanged by means of a
single or multiple connections and that employ identifiers with a high
priority.
•
explicit messages
These are used to establish multi-purpose point-to-point communication
paths between two devices which are used for the configuration of
network couplers and for diagnostic purposes. These functions usually
employ identifiers of a low priority.
Messages that are longer than 8Byte are subject to the fragmentation
service. A set of rules for master/slave, peer-to-peer- and multi-master
connections is also available.
General
DeviceNet