Echelon FTXL User Manual
Page 149
FTXL User’s Guide
137
A network variable connection is authenticated only if the readers and
writers have the authenticated keywords specified. However, if only the
originator of a network variable update or poll uses the keyword, the
connection is authenticated (although the update does take place). See
on page 44 for more information about authentication.
The default is nonauth (config).
Recommendation: Use the acknowledged service with authenticated updates.
Do not use the unacknowledged or repeated services.
priority | nonpriority [ ( config | nonconfig ) ]
Specifies whether the network variable update has priority access to the
communications channel. This field specifies the default value.
All priority network variables in a device use the same priority time slot
because each device is configured to have no more than one priority time slot.
The config keyword indicates that this service type can be changed by a
network management tool. This option allows the tool to change the service
specification during installation. config is the default
The nonconfig keyword indicates that this service cannot be changed by a
network management tool.
The default is nonpriority (config).
The priority keyword affects output or polled input network variables. When
a priority network variable is updated, its value is propagated on the network
within a bounded amount of time as long as the device is configured to have a
priority slot by a network management tool. The exact bound is a function of
the bit rate and priority. The delay before propagation for a nonpriority
network variable update is unbounded.
rate_est ( const-expr )
The estimated sustained update rate, in tenths of updates per second, that
the associated network variable is expected to transmit. The allowable value
range is from 0 to 18780 (0 to 1878.0 updates per second).
max_rate_est ( const-expr )
The estimated maximum update rate, in tenths of messages per second, that
the associated network variable is expected to transmit. The allowable value
range is from 0 to 18780 (0 to 1878.0 updates per second).
It might not always be possible to determine rate_est and max_rate_est. For
example, update rates are often a function of the particular network where the
device is installed. These values can be used by a network management tool to
perform network load analysis and are optional.
Although you can specify any value in the range 0 to 18780, not all values are
used. The values are mapped into encoded values in the range 0 to 127. Only the
encoded values are stored in the device's self-identification (SI) data. The actual
value can be reconstructed from the encoded value. If the encoded value is zero,
the actual value is undefined. If the encoded value is in the range 1 to 127, the
actual value is
5
)
8
/
(
2
−
=
n
a
, rounded to the nearest tenth. The value
a
, produced
by the formula, is in units of messages per second.