RS-232
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RS-422 INTERFACE CONVERTER
12
T
HE
R
ECEIVER
T
ERMINATION
S
WITCH
This switch is marked S1 on the printed circuit-board diagram in Figures 3-1 and 3-2. This switch serves
to terminate the receiver with pull-up and pull-down resistors in order to designate the receiver state and
enable the Converter’s anti-streaming function. Setting the switch to the ON position closes the switch,
setting the switch to OFF opens the switch.
3.2 LEDs
The RS-232
↔
RS-422 Interface Converter is equipped with seven LEDs located on the front panel that
indicate the status of INPUT signals.
The three LEDs on the right side of the front panel show conditions on the RS-232 interface: DSR
(Data Set Ready), CTS (Clear To Send), and Data.
The three LEDs on the left side of the panel show the same conditions on the RS-422 interface: DSR
(Data Set Ready), CTS (Clear To Send), and Data.
The LED labeled PWR, located in the center of the front panel, indicates when power is applied to
the unit.
Figures 3-5 and 3-6 illustrate signal flow in both the DTE and DCE configurations.
NOTE
Some LEDs may be lit when no input signal is present. This is not a malfunction, but a
floating state condition at the input that causes the output of that driver to indicate a
positive voltage condition.
