Lenze I/O system 1000 - 6.3 Communication

Lenze · I/O system 1000 · Reference Manual · DMS 5.0 EN · 09/2016 · TD17 218
6 PROFIBUS communication
6.3 Communication
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6.3 Communication
6.3.1 Bus access
The transmission protocol offers two bus access procedures.
Master
 Master
The master communication is also referred to as token passing procedure. The token passing
procedure makes sure that the bus access authorisation is assigned. The bus access authorisation is
given by means of a "token". The token is a special telegram transmitted via the bus.
If a master has a token, it can communicate with all of the other bus nodes. The token hold time is
defined during system configuration. Once the token hold time has elapsed, the token is passed on
to the next master which is then in possession of the bus access authorisation and can
communicate with all of the other nodes.
The data transfer between the master and the slaves assigned to it is automatically controlled by
the master and takes place in a fixed and recurring sequence. The slaves are assigned to a master
during configuration. In addition, it can be defined which slaves participate in the cyclic process data
transfer.
Master
 Slave
Before master and slave can communicate, the configuration and the parameter setting are
checked for errors after startup.
The following are checked: type, format information, length information and the number of inputs
and outputs.
If the parameters are valid, the slave changes over to the DataExchange (DE) state. The master can
now transmit output data to the slave and receive the current input data from the slave.
While the process data transfer is in progress, the master can transmit new parameter data to the
slave.