User's Manual

Company Confidential 17 Raveon Technologies
6.5 Addressing (Packetized Mode only)
Addressing Basics
One of the more powerful aspects of the M7-UC modem is its addressing
scheme. Incorporating addressing in the modem allows multiple radio
systems on the same frequency to co-exist, and not interfere with each other.
Also, some user application cannot tolerate receiving data that was not
intended for it, and by setting the addresses in the modems properly, the
system can be configured to allow reception of only data intended for the
recipient.
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 M7-UC contains a 16 bit address, called its Unit Address, and is
represented as a 4 digit hexadecimal number. M7-UC address may be any
number between 0000 and FFFF, which is effectively 65,535 different
addresses. Every M7-UC 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 M7-UC 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 M7-UC modem. The default Address Mask is FFFF, which means all
digits will be used.
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, M7-UC 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.