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E Series Ethernet Radio – User Manual
Collision Avoidance (Digital and Carrier Detect based)
Where multiple “unsynchronised” protocols coexist on a common “multiple access” radio channel, there is always a possibility that both “hosts”
may poll different “remote” devices at the same time. If both devices attempt to answer back to the single master radio at the same time, it
follows that a collision could occur on the radio channel.
Digital
If the “multiple access master” has been configured for full duplex operation, it is possible to use the inbuilt collision avoidance signalling
system.
A unit configured as a master of a collision avoidance scenario must be permanently transmitting.
Once the master radio receives a
valid incoming data stream from a remote, a flag within the “outbound” data stream is used to alert all other remote devices that the channel has
become busy. Remote devices wishing to send data will buffer the message until the channel status flag indicates that the channel is clear. A
pseudo-random timing value is added to the retry facility to minimise the chance of waiting remotes retrying at the same time.
RF Carrier Detect
In half duplex systems, the receiver’s RF carrier detect is used to inhibit the transmitter whilst a signal is being received. If a full duplex Base
station is employed, it can be configured to energise it’s transmitter with a blank carrier to inhibit other remotes from transmitting.
Security
AES Encryption
When encryption is enabled in a network, all data sent over the air is protected from eavesdropping and can only be read by radios sharing the
same Encryption Key.
Encryption must be enabled in each radio in a network. The encryption key is 128 bits long and is entered as a text string or a hexadecimal
number. For maximum security the key chosen should be one that is difficult for an intruder to guess.
Once written into the radio using the programmer, it is not possible to read the encryption key so care must be taken to record the key in a safe
place.
Encryption Key : String
For a string type of key, use up to a maximum of 16 printable characters. Please note that the key is case sensitive.
Some examples are:
TRIO2010
Murray River
Encryption Key : Hexadecimal Number
Hexadecimal numbers can have a value of 0 to 15 and are represented by 0-9 and A, B, C, D, E or F
A hexadecimal key begins with 0x and has up to 32 digits following
Some examples are:
0x123
0x123456789ABCDEF
0x1111111122222222333333334444444 up to 32 digits
Password Protected Configurations
Configuration information can be protected by a user definable password. When a password is set, the programmer will request the password
each time the radio is read. No configuration information can be displayed or changed without the correct entry of the password. If the password
is lost/forgotten the radio will have to be factory defaulted by depressing the factory default button on the front of the radio.
*Note - The password is NOT saved within a saved configuration and must be set within a programming session.
Part D – Features
