User's Manual

Company Confidential 24 Raveon Technologies Corp.
these settings, by default all M8s will talk to and hear all other M8S 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
M8S 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 M8S 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, M8S 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.
Setting A System-Wide Address
If individual addressing is not needed in your system, there are two ways to
ensure it is not used. One way is to set all modems in the system with the same
Unit Address and Destination Address. From the factory, these are both set to
1234, and thus, all modems can communicate with all other modems, using the
address 1234. The advantage of using this system-wide address, is that if there
are other M8S modems on the channel, but in some other system, they probably
will not have the same Unit Address, and thus will not interfere with your system.
To reduce the possibility of data cross-talk, the system implementer may wish to
use a different system-wide address for the Unit Address instead of 1234. There
are over 65,000 addresses available.
The ATLA command can be used to set an additional address that the M8S will
listen for.