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DB9 Connector Pinouts
Pin
Name
Direction
1
DCD
Out
2
RD
Out
3
TD
In
4
DTR
In
5
SG
6
DSR
Out
7
RTS
In
8
CTS
Out
9
RI
2.4.2 RS485 Serial Port
The RS485 port provides for communication between the XYR 400E unit and its host device using
a multi-drop cable. Up to 32 devices may be connected in each multi-drop network.
As the RS485 communication medium is shared, only one of the units on the RS485 cable may
send data at any one time. Thus communication protocols based on the RS-485 standard require
some type of arbitration.
RS485 is a balanced, differential standard but it is recommended that shielded, twisted pair cable
be used to interconnect modules to reduce potential RFI. It is important to maintain the polarity
of the two RS485 wires. An RS485 network should be wired as indicated in the diagram below
and terminated at each end of the network with a 120 ohm resistor. On-board 120 ohm resistors
are provided and may be engaged by operating the single DIP switch in the end plate next to the
RS485 terminals. The DIP switch should be in the "1" or "on" position to connect the resistor. If
the module is not at one end of the RS485 cable, the switch should be off.
17
Function
Data carrier detect –
Transmit Data – Serial Data Output
Receive Data – Serial Data Input
Data Terminal Ready -
Signal Ground
Data Set Ready - always high when unit is powered on.
Request to Send -
Clear to send -
Ring indicator -
XYR400E Ethernet Modem
Version 1
5/1/08
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