Quatech RS-485 user manual Termination Resistors, RS-422/485 Termination

Page 39

7.6 Termination Resistors

No termination resistors are provided on the ports. Both output and input signals are connected only to the external connector. Any termination which is required must be added externally.

RS-422/485 Receiver

+RXD+

Rt

-RXD-

RS-422/485 Receiver

+AUXIN+

Rt

-AUXIN-

Recommended Termination Resistor Values

RS-422	RS-485
100 ohm 1/2W resistor	60 ohms total resistance
	(120 ohms at each end)

Figure 21. RS-422/485 Termination

Quatech DSC-200/300 User's Manual

37

Image 39

Contents DSC-200/300 Date of Purchase Model Number Page Declaration of Conformity 4 TGL0SEL1,0, TGL1SEL1,0 J15,14,22,21 IND Option --- Surge Suppression UpgradeChanging Resource Settings with Device Manager 2 AUX0SEL1,0, AUX1SEL1,0 J12,11,19,18Half-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