Quatech DSC-200/300 user manual Half-Duplex/Full-Duplex Selection

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8.5 Half-Duplex/Full-Duplex Selection

Using jumper blocks J6 and J8, the transmitters and receivers of each channel can be enabled and disabled by modem control signals. This allows operation in both half-duplex or full-duplex modes.

The transmit drivers can be controlled by either the Data Terminal Ready (DTR) or the Request to Send (RTS) output from the UART. If a jumper is applied between pins 1 and 4, the drivers are enabled for TxD and AUXOUT when the UART's DTR signal is asserted. If a jumper is applied between pins 2 and 5, the drivers are enabled for TxD and AUXOUT when the UART's RTS signal is asserted. If neither of these jumpers is applied, the drivers remain enabled at all times. When disabled, the transmit drivers enter a high-impedance state.

The receivers can be controlled by the inverse of the transmit enable. If a jumper is applied between pins 3 and 6, the receivers for RxD and AUXIN will be disabled when the transmit drivers are enabled and vice-versa (based on the DTR or RTS connections on pins 1-4 or 2-5).

To operate in half-duplex DTR mode, apply jumpers between pins 1 and 4 and pins 3 and 6. To operate in half-duplex RTS mode, apply jumpers between pins 2 and 5 and pins 3 and 6.

To operate in full-duplex mode, leave the jumpers in their factory default locations, installed in the spare locations of 4-5 and 6-only. The drivers and receivers are always enabled in full-duplex mode. Figure 23 shows how to select half- or full-duplex operation.

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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Contents DSC-200/300 Warranty Information Page Declaration of Conformity Manufacturers Name RS-422 or RS-485 Signal Line Termination Using the New Hardware Found WizardAddress Map and Special Registers Base Address and Interrupt Level IRQPage General Information Features IND Option --- Surge Suppression UpgradeHardware Configuration Factory default signal termination settingsSignal Connections Full-duplex/Half-duplex OperationEnable Scratchpad Register SPAD, J13 Clock Rate and Optional RegistersForce High-Speed Uart Clock X2, X4, or X8, J10-J12 Clock multiplier jumper optionsHardware Installation Jumper/connector locationsChannel Address Range Enabling the Special Registers Interrupt Status RegisterOptions Register Bit Name DescriptionClock Rate Multiplier RR1 RR0Windows Configuration Windows MillenniumWindows Windows Windows Page Using the New Hardware Found Wizard Windows NT DOS and Other Operating Systems QTPCI.EXEQTPCI.EXE Basic Mode display QTPCI.EXE Expert Mode display OS/2 External Connections Jumper/Channel correspondenceRTS/CTS Handshake RclkXclk AUXIN/AUXOUT LoopbackHalf-Duplex/Full-Duplex Selection Half- or full-duplex selection Termination Resistors RS-422/485 Line termination resistance valuesDSC-200/300 connector definitions RS-422/485 Peripheral ConnectionPCI Resource Map INTA#10Specifications Troubleshooting Computer will not boot upDSC-200/300 Revision March
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