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7 Modbus RTU
7.1 General
DE1 variable speed starter
09/14 MN040011EN
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111
7 M
odbus RTU
7.1 General
Modbus is a centrally polled bus system in which a so-called master (PLC)
controls the entire data transfer on the bus. Internode communication
between the individual modules (slaves) is not possible.
Every single data-exchange operation is initiated by the master with a
request. Only one request can be sent on the cable at a time.
Slaves are not able to initiate transfers, and are only able to respond to
requests.
Two types of dialog are possible between master and slave:
•
The master sends a request to a slave and waits for a response.
•
The master sends a request to all slaves and does not wait for a
response (broadcast).
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For more information on Modbus, please visit: