6 External Connections

The QSC(LP)-200/300 provides four differential communication signals per channel. The two output signals are Transmit Data (TxD) and Auxiliary Output (AUXOUT). The two input signals are Receive Data (RxD) and Auxiliary Input (AUXIN). A ground signal is also provided.

The available input signals for AUXIN are Clear To Send (CTS) and the Receive Clock (RCLK). The available output signals for AUXOUT are Request To Send (RTS), the Transmit Clock (TCLK), and the AUXIN signal (for loopback). Either half-duplex or full-duplex operation can be selected for each communications channel. Auto-Toggle is also jumper selectable .If half-duplex operation is selected, one of the UART's signals (either DTR or RTS) is used to enable the transmitter drivers. The inverse of the transmitter enable can be used to enable the receiver drivers.

Configuration is usually done using Soft Select, accessable through Device Manager in Windows operating systems. Hardware overrides are available via jumper J1 for interface signal routing.

6.1 DTR/DSR or RTS/CTS Operation

The DTR or RTS modem control output of the UART can be used to enable and disable the transmit drivers. These options are selectable per channel. The factory default, with no jumpers across any of the pins in J1, is for both the drivers and receivers of both channels to be continuously enabled. . These option are not selectable via jumpers, they are only accessable through Device Manager under Window operating systems.

6.2 RTS/CTS Handshake

Transmission of RTS, combined with reception of CTS, allows for hardware handshaking (data flow control) between the UART and the external device. RTS is transmitted on AUXOUT and CTS is received on AUXIN by connecting a jumper across the “AUX” pins for the appropriate port of the jumper block J1. If RTS/CTS handshaking is not desired, the RTS output can be looped back to the CTS input by removing the any jumper from “AUX” pins for the appropriate port of the jumper block J1.

6.3 RCLK

This is the clock signal used by the receiver portion of the UART. It is generally provided by connecting it to the UART's own transmit clock output (TCLK). This signal can only be accessed via Soft Select through Device Manager. RCLK is affected by the “Loopback All”, “Modem Control”, or “Clocks” selections under “RS-422/485 connector set-up” on the RS-422/485 tab of each port’s property dialog.

6.4 TCLK

This is the output clock signal used by the transmitter portion of the UART. It is generally connected to the UART's own receive clock input (RCLK). This signal can only be accessed via Soft Select through Device Manager. TCLK is affected by the “Loopback All”, “Modem

Quatech QSC(LP)-200/300 User's Manual

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Quatech QSC(LP)-300 user manual DTR/DSR or RTS/CTS Operation, RTS/CTS Handshake, Rclk, Tclk