Radio/Serial Telemetry Module
User Manual
Page
22
©
March 2000
The serial port is a 9 pin DB9 female and provides for connection to a terminal or to a PC for
configuration, field testing and for factory testing. This port is internally shared with the RS485 -
ensure that the RS485 is disconnected before attempting to use the RS232 port. Communication is
via standard RS-232 signals. The 905 is configured as DCE equipment with the pin-out detailed
below. The serial port communicates at a baud rate of 9600 baud, 8 bits, no parity, one stop bit.
Pin
Name
Dirn
Function
1
DCD
Out
Data carrier detect - not used
2
RD
Out
Transmit Data - Serial Data Input (High = 0, Low = 1)
3
TD
In
Receive Data - Serial Data Output (High = 0, Low = 1)
4
DTR
In
Data Terminal Ready - not used
5
SG
-
Signal Ground
6
DSR
Out
Data Set Ready - not used
7
RTS
In
Request to Send - not used
8
CTS
Out
Clear to send - not used
9
RI
-
Ring indicator - not used.
An example cable drawing for connection to a laptop is detailed below:
MALE
FEMALE
2.4.11 RS485 Serial Port
The RS485 port provides for communication between multiple 905 units using a multi-drop cable.
Up to 32 units may be connected in each multi-drop network. Each multi-drop network may have
one unit providing radio communications with other units in the system. The RS485 feature allows
local hubs of control to operate without occupying radio bandwidth required for communication
between remotely sited units.
