Echelon LonPoint Application and Plug-In - Manual (Page 13)

The LonPoint Application and Plug-in Guide 1-7
any downstream functional blocks that check heartbeats to go into heartbeat failure
as well. Functional blocks which go into heartbeat failure will output their default
values (see Defaults, below)
You can disable heartbeat receive checking on downstream functional blocks. This
may be desirable in situations where it makes sense for the application to continue
to use the last known valid data rather than change to the configured default
network variable or hardware output.
Throttle
The throttle option limits the rate of updates on an output network variable. Use
throttling to reduce network traffic. In order to minimize network traffic, set the
throttle value to the longest interval between updates on the output network
variable that is compatible with correct system operation. Turn off throttling by
setting the value to 0. The AI and PID functional blocks produce data at their
configured scan interval, and do not have a throttle configuration property.
Default Values
Default values are values that apply to hardware outputs and both input and output
network variables.
A functional block will use its default hardware or network variable output value
when any of the following conditions occur:
•
The functional block has just come out of reset and has not yet received any
network variable updates.
•
The functional block has an enable input network variable which is turned off.
•
The functional block senses a heartbeat failure.
Default values for input network variables are used when any of the following
conditions occur:
•
The network variable has not yet received any updates since its last reset.
•
The network variable is not connected. There are often situations where one or
more inputs on a functional block will not be connected. The network variable
should be configured with an appropriate default input value. This also allows
you to manually set the value of an input network variable for debugging and
testing.
Override Values
Override values are values that apply to output network variables and hardware
outputs. LonPoint functional blocks can be forced into an override state with the
LonMaker tool or the LonPoint Plug-in. When a functional block is in the override
state, the output network variables and hardware outputs, if any, will be set to their
override values. Override values and the override state are preserved across power
cycles and resets.
While override values are stored in both the device and in the LNS database, the
override state of a device is stored only in the device, not in the LNS database. If you
replace a device with the LonMaker tool, the old device’s override values are