Chapter Three
Operation
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3.2.6
Testing and Commissioning
We recommend that you set-up and test the system with all of the modules together
before
you install the modules. It is much easier to find a configuration problem.
When the system is configured, record the radio signal strength and background noise level
for each radio link. If there are future communications problems, you can compare the
present measurements to the as-commissioned values.
3.3
Security Considerations
There are three dimensions of security considerations:
1.
Failure to operate when required - or “operational reliability”.
The features discussed above optimise operating reliability. Using an acknowledgement
and re-try protocol ensures that the transmitting module is aware whether the transmitted
message has been transmitted reliably. The “fail to transmit” and “fail to receive” alarms
provide indication if the radio link has failed to operate.
2.
Mal-operation, or operating when not requested.
This problem occurs when an output is “triggered” by the wrong radio device. The 905U
modules use frequency encoding and a very secure addressing system to ensure this does
not occur. An additional security level using data encryption can also be selected.
3.
Malicious operation, or “hacking”
This is the problem most associated with security concerns - the ability for someone to
access information from a radio system by “listening-in”, or to cause damage by
transmitting radio messages to force outputs.
A security option can be selected during the module configuration to protect against this.
The security option (if selected) adds data encryption to radio messages. Modules in the
same system are automatically configured with the encryption key, such that only these
modules can understand each other. “Foreign” modules will hear the messages, but
cannot decrypt the messages. For more information, refer to section 4.3.7.
