Despatch 926E Equipment Manual (C-155)Rev 2/11 - Manual (Page 52)

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Pinout Descriptions
Pin Out
Description
-RxD
Receive Data
Input - Pin 2
This pin accepts serial data sent by the RS-232 or RS-422 host. The
serial data is expected with the word length, baud rate, stop bits and parity
selected by the internal switches. The signal level is low true.
-TxD
Transmit Data
Output - Pin 3
This pin transmits serial data to the RS-232 or RS-422 host. The serial
data is sent with the word length, baud rate, stop bits and parity selected
by the internal switches. The signal level is low true.
CTS
Clear to Send
Input - Pin 4
The CTS input is used as a hardware handshake line to prevent the
interface converter from transmitting serial data when the RS-232 host is
not ready to accept it. When RTS/CTS handshake is selected on the
internal switches, the interface converter will not transmit data out -TxD
while this line is unasserted (low). If the RS-232 host is not capable of
driving this line it can be connected to the Vtest output (Pin 6) of the
interface converter. If XON/XOFF handshake is selected, the CTS line is
not tested to determine if it can transmit data.
RTS
Request to Send
Output - Pin 5
The RTS output is used as a hardware handshake line to prevent the
RS-232/RS-422 host from transmitting serial data if the interface
converter is not ready to accept it. When RTS/CTS handshake is
selected on the internal switches, the interface converter will drive the
RTS output high when there are greater than 1,000 character locations
available in its internal buffer. If the number of available locations drops
to less than 1,000, the interface converter will unassert (low) this output.
If XON/XOFF handshake is selected, the RTS line will be permanently
driven active (high).
Vtest
Test Voltage
Output -Pin 6
This pin is connected to +5 volts through a 1K resistor. It is also common
to Vtest on Pin 9.
Gnd
Ground
Pin 7
This pin sets the ground reference point for the other RS-232 inputs and
outputs.
Vtest
Test Voltage
Output - Pin 9
This pin is connected to 5 volts through a 1K resistor. It is also common
to Vtest on Pin 6.
+RxD
Receive Data Plus
Input - Pin 14
This pin accepts serial data sent by the RS-422 host. The serial data is
expected with the word length, baud rate, stop bits and parity selected by
the internal switches. The signal level is high true and only connected to
this pin when RS-422 operation is selected. It is 180 degrees out of
phase with -RxD.
+TxD
Transmit Data Plus
Output - Pin 16
This pin transmits serial data to the RS-422 host. The serial data is sent
with the word length, baud rate, stop bits and parity selected by the
internal switches. The signal level is high true and only connected to this
pin when RS-422 operation is selected. It is 180 degrees out of phase
with -TxD.