User manual

105G Wirless Gateway USer Manual

Elpro_man_105g_1.18.doc Page 26

For example, to monitor the comms status of I/O register 1045, perform a binary/discrete read on

comms fail, and a “0” returned if the status is normal.

If it is desired to monitor the comms status of all I/O points, it is more efficient to only monitor

the comms status of one I/O point at each remote module (if this point is in comms fail, then all

points at the remote module will be in comms fail). If this point is an input, then the comms fail

time for this input can be made short, to give an early warning of a comms problem (this means

that the corresponding update time for the input at the 105U will need to be short). If the point is

an output, then the update time for the output should be made short.

2.7 Security Considerations

There are three dimensions of security considerations:

1. Failure to operate when required - or “operational reliability”.

The features discussed above optimize operating reliability. Using an acknowledgment and

re-try protocol ensures that the transmitting module is aware whether the transmitted

message has been transmitted reliably. The “comms fail” 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 105G

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 4.2.2.