Profibus Dp Network Operation; Profibus Dp-V0; Cyclic Data; Sync/Freeze - WEG CFW500 User Manual

5 PROFIBUS DP NETWORK OPERATION

The CFW500 frequency inverter with Profibus DP communication accessory operates as a slave in the network
and supports the network services of DP-V0 and DP-V1 communication protocols. Information about the
inverter operation using the services specified on these versions is presented bellow.
5.1

PROFIBUS DP-V0

5.1.1

Cyclic Data

The communication via cyclic data allows the data transfer in two directions:
Input data: Data transmitted from the slave to the master, for monitoring the status and the variables of

each slave.
Output data: Data transmitted from the master to the slave, for control and transmission of operation data

to the equipment.
These data are transmitted in regular time periods, defined by the baud rate, number of slaves in the network
and the amount of data exchanged with each slave.
The number of input/output (I/O) words available for the CFW500 depends on the format of the configuration
telegram, programmed through the parameter P0922. It is possible to communicate from 2 to 10 input words
and the same number of output words. The contents of these words depend on the setting of the parameters
P0741 to P0757.
The same programming done at the parameter P0922 must also be configured at the network master, using a
master configuration tool and the CFW500 GSD file, selecting one of the available modules described in the
GSD file.
5.1.2

SYNC/FREEZE

The CFW500 frequency inverter supports the SYNC/UNSYNC and FREEZE/UNFREEZE commands. These are
global commands that the master can send to all the network slaves, allowing simultaneous update of I/O data
in the network equipments.
The SYNC/UNSYNC commands act on the master output data. When receiving a SYNC command, the
command and speed reference values received by each slave are frozen. Values received later by the slave are
stored, but will only be updated after the reception of a new SYNC command, or after the UNSYNC command,
which cancels this function.
The FREEZE/UNFREEZE commands act in a similar form as the SYNC, but their action is associated to the
master input data. When receiving a FREEZE command, variable and status values of each slave are frozen.
These values remain fixed until a new FREEZE command be received, or after the UNFREEZE command, which
cancels this function.
5.2

PROFIBUS DP-V1

In addition to the services defined by the first version of the Profibus DP specification (DP-V0), where it is mainly
defined how to perform the exchange of cyclic data for equipment control and monitoring, the CFW500
frequency inverter with the Profibus DP communication accessory also supports the DP-V1 additional services
for acyclic communication. Using these services, it id possible to read/write drive parameters using DP-V1
acyclic function, both by the network master (class 1 master) and by a commissioning tool (class 2 master).
5.2.1

Available Services for Acyclic Communication

The device supports the following services for acyclic communication in the Profibus DP network:
Communication between class 1 master and slave (MS1):

Data acyclic reading (DS_Read)

Data acyclic writing (DS_Write)

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