HART Device Electronic Keying
The Electronic Keying feature for HART devices automatically compares the expected device
to the physical device before connection is established. You can use Electronic Keying
to help prevent connection to a device that does not match the type and revision
expected.
For each device, the selected keying option determines if, and how, an Electronic Keying
check is performed.
The three keying options that are available are:
- Compatible Module (default)
- Exact Match
- Disable Keying
Compatible Module is the default setting. It allows the physical device to accept the key
of the device configured in the software, if the configured device is one that the
physical device is capable of emulating. The exact level of emulation that is required
is defined as follows:
- HART Expanded Device Type must match.
- Major revision of the physical device must be greater or equal than the configured major revision.
- If major revision exactly matched, minor revision of the physical device must be greater or equal than the configured minor revision if the configured minor revision is not 0.
Disable Keying indicates that the keying attributes are not considered when attempting to
communicate with a device. Other attributes, such as data size and format, are
considered and must be acceptable before connection is established. With Disabled
Keying, connection can occur with a device other than the type specified in the I/O
configuration tree with unpredictable results.
WARNING:
Be extremely cautious when using Disable Keying; if used incorrectly, this option
can lead to personal injury or death, property damage, or economic loss.
You do not use Disable Keying. If you use Disable Keying, you must take full
responsibility for understanding whether the device being used can fulfill the
functional requirements of the application.
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