13 Communication Protocols
13.1 Brief Introduction
EFC 3600 frequency converters provide standard RS485 communication port to
realize the communication between the master and slaves via ModBus or
PROFIBUS protocol.
①
With the help of a PC, a PLC or an external computer a
"single master/multiple slaves" network control can be realized (setting of fre-
quency control command and running frequency, modification of parameters,
monitoring of frequency converter running status and failure messages) to ad-
dress the specific requirements of applications.
①
：Notes on EFC 3600 available communication protocols
● EFC3600-xKxx-xPx-MDA-7P-NNNN (MDA) models: only ModBus
protocol available
● EFC3600-xKxx-xPx-PDA-7P-NNNN (PDA) models: ModBus and
PROFIBUS protocols optional
13.2 ModBus Protocol
13.2.1 Protocol Description
Brief introduction
● ModBus is a master/slave protocol. Only one device may send commands in
the network at a particular time.
● The master station manages message exchange by polling the slave stations.
Unless being approved by the master station, no slave station may send mes-
sage. In case of an error during data exchange, if no response is received, the
master station will query the slave stations absent from the polling.
● If a slave station is unable to recognize a message from the master station, an
exception response will be sent to the master station.
● Slave stations cannot communicate with each other but through the master’s
software which reads data from one slave station and sends them to another.
There are two types of dialogs between the master station and the slave sta-
tions:
– The master station sends a request to a slave station and waits for its re-
sponse.
– The master station sends a request to all slave stations and does not wait
for their response (broadcasting).
Bosch Rexroth AG
Communication Protocols
EFC 3600
184/259
DOK-RCON03-EFC-3600***-IT03-EN-P
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