Hardware automatically enables the
transmitters when transmitting.
Transmitters will turn off three bit-times
after the last stop bit of the last
character, regardless of baud rate. Used
in two-wire communication.
Auto Toggle
DTR is set to enable the transmitters.
Used in two-wire communication
Half Duplex using DTR
RTS is set to enable the transmitters.
Used in two-wire communication.
Half Duplex using RTS
Transmitters and receivers are always
enabled; ports can send and receive
simultaneously. Used in four-wire
communication.
Full Duplex
RS-422/485 Duplex Mode
Receivers are only enabled when not
transmitting. In a Half Duplex mode,
you will not receive what you transmit.
When NOT Tranmitting
8. To summarize the RS-422/485 output drivers enable options: The
QSC(LP)-200/300’s ports may be configured for either full duplex or half duplex
operation with this option. The default setting is the RS-422/485 ports are configured
for full duplex operation with the RS-422/485 output drivers always enabled. In half
duplex mode, the RS-422/485 transmitter may be enabled and disabled via the RTS
(request to send) or DTR (data terminal ready) signals, or in auto-toggle mode, set to
enable only when data is being transmitted. Both RTS and DTR are controlled
through the Modem Control Register of the 16750.
9. Click the "Port Settings" tab and then click the "Advanced" button. The
QSC(LP)-200/300 driver will display a custom Advanced Port Settings control, which
allows the ports UART compatibility mode and FIFO threshold levels to be
configured. The threshold values of full-scale for the transmit buffer and ¾-scale for
the receive buffer are optimal for most applications. Note that the FIFO option for
each of the QSC(LP)-200/300's four ports is configured independently.
Quatech QSC(LP)-200/300 User's Manual
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