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

Profibus-dp, communication module cm-pdp, frequency inverter 230v/400v

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Table Of Contents

Table of Contents

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 canceled and the slaves

update their inputs again.

With the SYNC command, all the slaves keep their outputs. Data arriving subsequently

are not put through to the outputs, but buffered. The bus master can give new com-

mands to the slaves and activate all the slaves simultaneously with the UNSYNC com-

mand. They immediately take over the buffer data to their outputs with the UNSYNC

command.

If a Profibus slave has been recognized, parameterized and convalued by its master

on the bus, there is a cyclic exchange of data with the DATA_EXCHANGE Profibus

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 repeat 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 set, 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.

As it can be seen from what has just been said that the possible bus rotation time also

depends to a considerable extent on the size of the objects to be transmitted, the

frequency inverter offers a selection between four different objects PPO1 to PPO4.

In this way, an optimum adaptation to differing situations and requirements is possi-

ble.

The objects defined according to PROFIDRIVE principally have two components, which

are either completely, partly or not at all existent with the differing objects PPO1 to

PPO4. These components are the communication channel and the process data chan-

nel.

The communication channel is used for access (write/read) to any parameters in

the frequency inverter. An exception is formed by the string parameters, to which

there can be 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 is processed in every cycle. The reference values are

accepted and the actual values forwarded. A data update thus takes place with every

DATA_EXCHANGE.

Direction of transmission Master

PKW

PZD

06/05