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D301171 - IO-Link master 1108
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Short Description of PROFIBUS-DPV1
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Short Description of PROFIBUS-DPV1
General
PROFIBUS-DPV1 is an enhancement of PROFIBUS-DP which provides the possibility of
acyclic data communication.
A cyclic and centrally directed data transfer between master and slaves is characteristic for
the standard functions of PROFIBUS-DP. A Class1 master (PLC) controls the cyclic exchange
of process data with the slaves. The data exchange is carried out in rotation and in a defined
order. The data which have to be transmitted are projected beforehand.
Via acyclic communication functions, PROFIBUS-DPV1 now offers the possibility to transmit
data to the slave in addition to the cyclic process data.
Acyclic data transfer
The need for acyclic data transfer exists wherever slave devices which provide several param-
eterization options have to be parameterized during operation.
Typical examples are the parameters of a drive, like limit values, rotational speed or torque,
operation mode and the generation of an error list.
Acyclic services are handled with low priority, parallelly and additionally to the cyclic process
data transfer. The negative influence on the speed of the high-priority process data transfer,
shall thus be minimized.
DPV1-functions
The DPV1-functions consist basically of the services "Read" and "Write". The master uses
these services for read- or write access to data blocks in PROFIBUS.
In addition to that, an "intiate" and "abort"-service for the connection management, a "data-
transport"-service for the exchange of large data packages and the "alarm"-and "status"-
services for the transmission of alarm messages have been defined.
DPM1 versus DPM2
PROFIBUS-DPV1 differentiates between two master classes.
An automation system (PLC), which generally controls the basic cyclic process data transfer
with standard DP-functions, is defined as Class1-master. A Class1-master can use DPV1-
functions optionally.
The new Class2-master is generally an engineering tool which is used for the acyclic data
transfer.
The protocol cycle of the DPV1-functions on the fieldbus depends on the use of a Class1- or
a Class2-master.
Note
At present, the BLxx-gateways for DPV1 only support the services "Read" and
"Write".