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Control”, or “Clocks” selections under “RS-422/485 connector set-up” on the RS-422/485 tab of
each port’s property dialog.
6.5 AUXIN/AUXOUT Loopback
The AUXIN signal is an input from the external device, and connecting it to the
AUXOUT signal provides for a loopback mode of operation. In other words, whatever signal is
transmitted by the external device over the AUXIN line will be fed back to the external device
over the AUXOUT line. This mode is accomplished by default or by removing the jumper from
the “AUX” pins for the appropriate port of the jumper block J1.
6.6 Half-Duplex/Full-Duplex/Auto-Toggle Selection
Using the hardware overrides provided by jumper block J1, the transmitters and receivers
of each channel can be forced into Auto-Toggle mode. Additionally, operation in either
half-duplex or full-duplex modes can be implemented via Soft Select, which is accessable via
Device Manager under the Windows operating system.
The transmit drivers can be controlled by either the Data Terminal Ready (DTR) or the
Request to Send (RTS) output from the UART. When disabled, the transmit drivers enter a
high-impedance state. The receivers can be controlled by the inverse of the transmit enable.
The drivers and receivers are always enabled in full-duplex mode.
WARNING:
When operating in half-duplex mode, the transmitter drivers must
be disabled before receiving any data. Failure to do so may result
in multiple active output drivers being connected together, which
may cause damage to the board, the computer, and the external
device.
Quatech QSC(LP)-200/300 User's Manual 25