Company Confidential
27
Raveon Technologies Corp.
If addressing is not needed or desired, it can be turned off so that all modems
receive data from all other modems, and all modems can talk to all other
modems.
Each
M8T
contains a 16 bit address, called its Unit Address, and is represented
as a 4 digit hexadecimal number.
M8T
address may be any number between
0000 and FFFF, which is effectively 65,535 different addresses. Every
M8T
has
a Unit Address programmed into it, as well as the ID of the unit it will send data
to. The Unit Address is programmed with the
ATMY xxxx
command, and the
Unit Address of the destination modem (the Destination Address) is configured
with the
ATDT xxxx
command.
The defaults UNIT ID in al
M8T
modems is 1234, and 1234 is the default for the
destination ID. An Address Mask is used to select which digits of the address will
be used to determine if a particular reception was intended for the M8T modem.
The default Address Mask is FFFF, which means all digits will be used. With
these settings, by default all M8s will talk to and hear all other M8T radio
modems.
Group Numbers
By default the M8’s Group Number is 0. Group 0 means ignore the group
numbering. The Group Number is set with the
ATGP xx
command, where xx is
the group number.
ATGP 0
disables group numbering and is the default way the
M8T radio modem works. If the Group Number is set to any non-zero number
from 1-255, then the group feature is enabled, and the group number will be the
group specified in the
ATGP
command. When enabled, the M8T will only
communicate with other M8s that have the same Group Number.
Hexadecimal Numbers
For those not familiar with hexadecimal numbers, a hexadecimal digit represents
a 4-bit binary pattern. There are 16 possible values
(0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,and F). These 16 values represent 4 bits of
information, thus 4 hexadecimal digits can represent 16 bits of information. The
hexadecimal numbers represent 4 bit data in the following way:
Hexadecimal Table
Hex #
Binary
Hex #
Binary
Hex #
Binary
Hex #
Binary
0
0000
5
0100
8
1000
C
1100
1
0001
6
0101
9
1001
D
1101
2
0010
7
0110
A
1010
E
1110
3
0011
8
0111
B
1011
F
1111
When communicating over the air,
M8T
modems transmit their Unit Address and
the Destination Address along with the data. Receiving modems check the
received Destination Address, and see if it matches their Unit Address. If it does
match, the receiving modem outputs the data it received via its serial port. If it
does not match, the receiving modem discards the data, and does not send it out
the serial port.
