Echelon Neuron C User Manual
Page 189
Neuron C Reference Guide
169
priority | nonpriority [( config | nonconfig )]
Specifies whether a network variable update has priority
access to the communications channel. This field specifies
the default value. The config and nonconfig keywords
specify whether the priority designation can be changed
by a network tool. The default is config. 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 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 over the network within
a bounded amount of time as long as the device is
configured to have a priority slot by a network tool. The
exact bound is a function of the bit rate and priority. This
is in contrast to a nonpriority network variable update,
whose delay before propagation is unbounded.
rate_est (
const-expr
) The estimated sustained 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 network variable
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 network variable
updates per second).
Note: 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 tool to perform network load analysis and are
optional.
Although any value in the range 0..18780 can be specified,
not all values are used. The values are mapped into
encoded values
n
in the range 0..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..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.