ADLINK C485 - Manual (Page 41)

Converter
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5.1 RS422 Interface Application Notes
The RS422 interface is used for point to point connections or multi-drop ap-
plications. Users may need to keep in mind that only one driver output signal
can be active in one time, or you could damage the driver IC.
Even though there is one 120 ohm terminator resistor in each input signal pair,
Users may need to remove this terminator resistor for proper operation.
For proper operation, don’t leave cables unconnected. Crosstalk can occur,
leading to transition data coupled to receiving data input.
5.2: RS485 Interface Application Notes
The RS485 interface is used for multi-drop half-duplex applications. Users
may not use RTS signals to control data direction because of its
Auto-Data-Direction-Control capability. There is one 120ohmn terminator
resistor in each RXD input signal pair. Users may or may not need to remove
this terminator resistor for proper operation.
For proper operation, don’t leave cables unconnected. Crosstalk can occur,
leading to transition data coupled to receiving data input.
The relationship between DATA+/DATA- and signals on the UART may be
different from other manufacture’s definition. In our RS4232, DATA+ is in
phase as signal in UART (not inverted).
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