Commands Sync/Freeze; Available Objects/Scanning Times - BONFIGLIOLI Vectron ACTIVE CUBE Manual

11 Commands SYNC/FREEZE

The Profibus component supports the Profibus commands SYNC/UNSYNC and
FREEZE/UNFREEZE. These commands are used to synchronize a number of slaves.
With the FREEZE command, all the slaves keep their input data. They are then read
out in sequence by the bus master. As all the slaves keep their inputs simultaneously
with the FREEZE command, the bus master is given a process pattern of all the slaves
at a defined time. With the UNFREEZE command, this state is cancelled and the slaves
update their inputs again.
With the SYNC command, all the slaves retain their current outputs. Subsequently
arriving data are not put through to the outputs, but buffered. The bus master can
give new commands to the slaves and activate all the slaves simultaneously with the
UNSYNC command. They immediately transfer the buffer data to their outputs with
the UNSYNC command.

12 Available objects/scanning times

If a Profibus slave has been recognized, parameterised and configured by its master
on the bus, there is a cyclic exchange of data with the Profibus DATA_EXCHANGE
service, in which the output data are transmitted from the master to the slave and the
input data from the slave to the master in one cycle. The repetition rate with which
the slaves carry out the exchange of data with the master, the so-called bus rotation
time, is a function of the transmission rate, the number of subscribers and the size of
the objects transmitted. If there are few subscribers, a high transmission rate and
short objects being exchanged, bus rotation times of 1 to 2 ms are possible.
It is therefore sensible to configure the objects to suit the application. Depending on
the application the focus can be transmission speed, number of objects or a combina-
tion of both.
The configured data exchange objects have principally two components, which are
either completely, partly or not at all existent with the differing object configurations.
These components are the communication channel and the process data channel.
The communication channel (PKW object) is used for accessing (write/read) para-
meters in the frequency inverter. An exception is formed by the string parameters, to
which there is NO access. The communication proceeds according to a firmly defined
hand-shake process and lasts for a number of DATA_EXCHANGE cycles.
The process data channel (PZD objects) is processed in every cycle. The reference
values are accepted and the actual values forwarded. Therefore a data update takes
place with every DATA_EXCHANGE.
Direction of transmission Master
PKW
PZD
Outx = user defined
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communication channel
PKW area
PKE IND PWE PWE PZD 1 PZD 2
PWEh PWEl
Parameter identification value
Process data channel
CM-PDPV1
Slave (OUT)
process data channel
PZD x
STW HSW Outx
STW = Control word HSW = Main reference value
CM-PDPV1
PZD area
PZD x PZD x PZD x
Outx Outx Outx
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