Lenze I/O system 1000 System Manual - Manual (Page 557)

DeviceNet communication
About DeviceNet
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557 EDSIO1000 EN 7.0
11 DeviceNet communication
11.1 About DeviceNet
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 standardised 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 devices recognize a suitable
identifier, they act and consume the respective data.
DeviceNet carries two types of messages:
ƒ I/O messages
Messages that are subject to critical timing constraints and contain data for control
purposes that can be exchanged by means of single or multiple connections and that
employ identifiers with a high priority.
ƒ 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 8 bytes are subject to the fragmentation service. A set of
rules for master/slave, peer−to−peer− and multi−master connections is also available.