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Communication protocols
Modbus > Modbus Master - Parameter
Interface
Wiring receiver
54
Here it is to specify if the interface is operated in half- (RS485) or full-duplex (RS422)
operation.
n
Full-duplex (RS422)
–
Four-wire operation (default value: active)
Data is exchanged between the communication partners in both directions simul-
taneously. In full-duplex operation, therefore, data may be sent and received at
the same time. Each communication partner must be able to operate a send and
a receive facility simultaneously.
n
Half-duplex (RS485)
–
Two-wire operation (default value: not activated)
Data is exchanged between the communication partners but only in one direction
at a time. In half-duplex operation, therefore, at any one time data is being either
sent or received. This setting is only available with the ASCII protocol.
n
Initial state of the receive lines
–
For a connection with minimum reflections and the break evaluation at
RS422/485 operation, the lines may be preset with defined static voltage levels.
At the CP interface the wiring of the receiver is realized as follows:
Parameter
None
(default value: not activated)
Parameter
Signal R(B) 0Volt
Signal R(A) 5Volt
(Break evaluation)
Parameter
Signal R(B) 5Volt
Signal R(A) 0Volt
(default value: not activated)
Description
No pre-assignment of the receiving lines.
This setting only makes sense with bus-capable spe-
cial drivers.
Description
With this pre-assignment break detection is possible at
full-duplex operation (RS422).
Description
This pre-assignment corresponds to the idle state (no
sender is activated) at half-duplex operation at RS485.
Here wire-break recognition is not possible.
HB130 | CP | 341-1CH01 | en | 18-40
VIPA System 300S
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