Quatech QSC(LP)-300 AUXIN/AUXOUT Loopback, Half-Duplex/Full-Duplex/Auto-Toggle Selection

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.

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