M7 GX Technical Manual
4
Raveon Technologies Corp.
5. RS232 Serial I/O Connector
The RS232 9-pin serial I/O connector is a female 9-pin D-
subminiature connector having
the following pins configuration. It is pinned out so that it
may be plugged directly into a
computer or PC’s 9-pin COM port.
Front-view of DB-9 connector on modem (female)
Pin
Name
Dir
Function
Level / Specification
1
CD
out
Carrier
detect
Indicates presence of carrier. Logical 0 means carrier is present. If disabled, it is
asserted (0). It will be a 1 when the modem is in the configuration mode.
2
RxD
out
Receive data
Data out of the modem.
3
TxD
in
Transmit
data or IN
2
Data into the modem.
Also used as digital input IN2 for exception reporting. GND or floating for a 0, >3V for
digital 1.
4
DTR
in
Data terminal
ready or IN
0
Used as digital input IN0 for exception reporting. GND or floating for a 0, >3V for digital
1. Use the TRIGBITS command to set which bits are used as inputs.
5
GND
Ground
connection
Signal and power ground
6
DSR
out
Data Set
Ready
Normally is set to 0 when modem is powered on and running. Modem sets to a 1 when
in low-power mode.
7
RTS
in
Request to
send
or
IN
1
Used to stop/start the flow of data out TxD pin. 0 = OK, 1 = don’t send.
Also used as digital input IN1 for exception reporting. GND or floating for a 0, >3V for
digital 1.
8
CTS
out
Clear to send
Used to stop the flow of data going into the RxD pin from the device connected to the
M7
. 0 = OK to send, 1 = don’t send
9
Power
In or
out
DC power
User may supply the DC power to the modem on this pin. If the DC input connector is
used to power the radio, then the DC power will also be on this pin.
Note: RS-232 signals use positive and negative voltages to represent digital 1s and 0s. A positive voltage is a 0, and a
negative voltage is a digital 1.
This pin-out allows it to be directly plugged into a computer’s 9-pin serial port using a conventional 9-pin RS-
232 serial cable. To connect it to a modem, or peripheral that has a serial port, you will need a “
null-modem
”
cable.
IN 2
(TXD)
IN 1
(RTS)
IN 0
(DTR)
Hexadecimal
Representation
0
0
0
0
0
0
1
1
0
1
0
2
0
1
1
3
1
0
0
4
1
0
1
5
1
1
0
6
1
1
1
7
6. Configuring the M7 GX
6.1.
Overview
There is a “Command Mode” used to program and configure the
M7 GX
. In the Command Mode, the
M7 GX
modem accepts commands via the serial port and the user may configure the internal parameters of the unit,
such as frequency and ID codes.
6.2.
Command Mode
The
M7 GX
modem may be put into a “Command Mode”, by entering a sequence of three plus characters
(+++). Using serial communications software such as
HypterTerminal
, send the 3-character command
sequence “+++”.
When the
M7 GX
modem first enters the Command Mode, it sends its model number out its serial port, and
then an “OK”.
