LRS400S Data Transceiver Users Manual
LUM0025AA Rev A
Version 1.0
30
RS-422
AND
RS-485
F
ULL
D
UPLEX
P
IN
-O
UTS
Function
Bare Board Pin Number
DE-9 Pin Number
RX+ 7
3
RX- 9
7
TX+ 5
2
TX- 10 8
Signal Ground
4 or 6
5
RS-485
H
ALF
D
UPLEX
P
IN
-O
UTS
Function
Bare Board Pin Number
DE-9 Pin Number
Wire to both pins for Bus +
Short 5 and 7
Short 2 and 3
Wire to both pins for Bus -
Short 9 and 10
Short 7 and 8
Signal Ground
4 or 6
5
RS232 Pin Assignments
Pin
Assignment
Signal
Definition
1
CD
Carrier Detect
Output
Used to show an RF connection between transceivers.
2 TX Transmit
Data
Output Used to transmit data bits serially from the transceivers to the
system device.
3 RX Receive
Data
Input Used to receive data bits serially from the system device
connected to the transceivers.
4
DTR
Data Terminal Ready
Input
Used only in transceivers in Point-to-Point Slave/Master
switchable mode or for DTR Connect.
5
GND
Ground
Signal return for all signal lines shared with Pin 9.
6
DSR
Data Set Ready
Output
Always high when the radio is powered from the 2.5mm
power connector. Indicated power is on to the radio. Also,
this pin can be used for +12Volts when powering the
transceivers directly through the RS-232 port.
Note:
This is not used on the OEM module.
7
RTS
Request to Send
Input
The transceiver does not recognize RTS for flow control. RTS
is used as a control line in RTS/CTS mode.
8
CTS
Clear to Send
Output
This signal is used to tell the system device connected to the
transceiver that the transceiver is ready to receive data.
When asserted, the transceiver will accept data, when
deasserted the transceiver will not accept data. This should
always be used for data rates above 38.4KB or there will be a
risk of lost data if an RF link is not very robust.
9
GND
Ground
Signal return for all signal lines shared with Pin 5.
