WI-I/O 9-K
v1.9
Page 22
Power for pulse input
Average pulse rate is 1 pulse per hour (0.0003Hz), so power required = 0.06 x 0.0003 per day
=
zero
Quiescent power
Power for quiescent current
=
3.4 per day * 365
=
1241 mAHr per year
Total power consumption per year
=
15 + 526 + 0 + 1241
=
1782 mAHr
Expected battery life is
=
1700/1782
= 0.95 year
Note that battery life is shortened during configuration or diagnostics. When the serial cable is
connected to the WI-I/O K, the module does not revert to sleep mode and the power
consumption is considerably increased. These periods should be minimised if you are using a
battery pack.
2.7
Security Considerations
There are a couple of dimensions of security considerations:
•
Failure to operate when required - or “operational reliability”.
The other WI-I/O 9-x modules use an acknowledgment and re-try protocol to ensure that the
transmitting module is aware whether the transmitted message has been transmitted reliably. The
WI-I/O K module is not able to do this, and hence does not have the same level of reliability.
However the ability to transmit each message multiple times does improve the reliability. A
“fail to receive” alarm at the receiver provide indication if the radio link has failed to operate.
•
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 of the WI-I/O 9-x I/O User Manual.
