Quatech RS-485 user manual Signal Connections, Full-duplex/Half-duplex Operation

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2 Hardware Configuration

The DSC-200/300 is automatically configured at boot time by the computer's BIOS or operating system. There are no required switches or jumpers to set for installation.

This chapter lists a number of optional jumper settings that control various hardware features. These jumpers, located in a column at the end of the board opposite the D-type connectors, control how signals are routed from the UARTs to the connector, as well as full- or half- duplex operation and special options.

Any changes from the factory default should be made before installing the DSC-200/300 in the computer.

2.1 Signal Connections

The DSC-200/300 provides each of two serial ports with four differential signal pairs: TxD, RxD, AUXOUT, and AUXIN. TxD and RxD are always present at the connector. The AUXOUT and AUXIN signals can be used to support RTS/CTS handshaking, external clocking, or external signal loopback. The factory default configuration, as shown in Figure 2, is a loopback of AUXOUT to AUXIN at the connector, with RTS and CTS looped back on the board. There is an extensive discussion of this topic in section 7.

2.2 Full-duplex/Half-duplex Operation

The DTR or RTS modem control output of the UART can be used to enable and disable the transmit drivers. The inverse of these signals can also be used to enable and disable the receivers. These options are selectable per channel. The factory default, as shown in Figure 2, is for both the drivers and receivers of both channels to be continuously enabled. Spare jumpers are installed in neutral positions. For details, refer to section 7.5.

The DSC-200/300 is shipped from the factory with each channel configured with No jumpers on J10-23. The following conditions occur: CTS=AUXIN, AUXOUT=RTS, RCLK=TCLK, TXEN=1 AND RXEN=1.

Quatech DSC-200/300 User's Manual

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Contents DSC-200/300 Date of Purchase Model Number Page Declaration of Conformity Changing Resource Settings with Device Manager IND Option --- Surge Suppression Upgrade2 AUX0SEL1,0, AUX1SEL1,0 J12,11,19,18 4 TGL0SEL1,0, TGL1SEL1,0 J15,14,22,21Half-Duplex/Full-Duplex/Auto-Toggle Selection External ConnectionsGeneral Information DSC-200/300 Product Series Summary FeaturesFull-duplex/Half-duplex Operation Signal ConnectionsJumpers J10-J23 define the options for this card 1 CTS0SEL, CTS1SEL J10,17 RCLK0SEL, RCLK1SEL J13RXEN0SEL, RXEN1SEL J16 Clock Rate and Optional Registers Enable Scratchpad Register SPAD, J2Clock multiplier jumper options Hardware Installation Base Address and Interrupt Level IRQ Interrupt Status Register Enabling the Special RegistersQuatech Modem Control Register Quatech Modem Control RegisterBit Name Description Options RegisterRR1 RR0 Clock Rate MultiplierWindows Millennium Windows Windows Windows Windows NT Viewing Resources with Device Manager Quatech DSC-200/300 PCI Two-Port RS-422/RS485 Serial Adapter Adapter Data Rate Multiplier Application. This mode is useful for legacy Used when external handshaking or Page DOS and other operating systems OS/2QTPCI.EXE QTPCI.EXE Expert Mode display Jumpers J10-12 RTS/CTS HandshakeTclk RclkAUXIN/AUXOUT loopback AUXIN/AUXOUT LoopbackHalf/full-duplex and Auto-Toggle selection RS-422/485 Termination Termination ResistorsRS-422/485 Peripheral Connection DSC-200/300 connector definitionsPCI Resource Map Specifications Computer will not boot up