Amplicon USB232U, Instruction Manual

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USB232U/485Ui
Page 7
2.3 USB232U/485Ui Configuration Jumper Settings
Most configuration settings on the USB485Ui are performed by the plug and play installation
program. However the USB485Ui has some jumpers and these need to be set before
connecting the unit to the host. The functions of the jumpers on the USB485Ui control whether
the unit operates in Full Duplex or Half Duplex mode and whether or not the RS485 port is
terminated.
2.3.1 RS485 Full Duplex / Half Duplex Operation
The RS485 port on a USB485Ui can be used in either full duplex or half duplex.
In full duplex operation, the transmitter can be left in its enabled state at all times. In half
duplex receive operation, the transmitter must be disabled by switching to its high impedance
state. This allows reception of data over the same serial lines.
2.3.1.1 Jumper Selection For Full Duplex Operation
Link Function
JP2 2-3
JP3 2-3 Full Duplex (4 wire) operation
JP4 1-2 Receiver enabled when device is awake
JP5 2-3 Transmitter enabled when device awake
Figure 2.1 Jumper Settings For Full Duplex Operation
2.3.1.2 Jumper Selection For Half Duplex Operation with Echo
Link Function
JP2 1-2
JP3 1-2 2 wire operation.
TxA is connected to RxA’ and TxB is connected to RxB’
JP4 1-2 LOCAL ECHO ON
Receiver enabled when device is transmitting
JP5 1-2 Transmitter only enabled when device is transmitting
Figure 2.2 Jumper settings for Half Duplex Operation with Echo
2.3.1.3 Jumper Selection For Half Duplex Operation without Echo
Link Function
JP2 1-2
JP3 1-2 2 wire operation.
TxA is connected to RxA’ and TxB is connected to RxB’
JP4 2-3 LOCAL ECHO OFF.
Receiver disabled when device is transmitting.
JP5 1-2 Transmitter only enabled when device is transmitting
Figure 2.3 Jumper settings for Half Duplex Operation without Echo