Quatech RS-422 - Manual (Page 30)

7 External Connections
The DSCLP-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 (XCLK), and the AUXIN signal (for loopback).
Either half-duplex or full-duplex operation can be selected for each communications
channel. 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.
Factory-installed resistors allow for signal line termination in compliance with the
RS-422 and RS-485 standards. The desired termination can be selected or removed
per port by applying a jumper.
Configuration is done using jumpers J1 through J4 for termination selection, and
jumpers J5 through J8 for interface signal routing. Each jumper block provides the
same functions for its particular channel.
J7, J8 J3, J4 Port 2
J5, J6 J1, J2 Port 1
Signal routing Termination Channel
Figure 17 --- Jumper/Channel correspondence
CTS
AUXIN
XCLK
RTS
AUXOUT
RCLK
1
2
3 6
5
4
1
2
3 6
5
4
RTS
DTR
Tx ENABLE
Tx ENABLE
Tx ENABLE Rx ENABLE
Half-duplex
if 3-6 shorted
Jumpers J6, J8
Jumpers J5, J7
Figure 18 --- Pinout of jumpers J5-J8
DSCLP-200/300 User's Manual 25