Specifications

APPENDIX C: EVENT PROGRAMMING
Page 182 MRC-565 Packet Data Radio Operations & Maintenance
Event definition
An "event" occurs when some input signal or timer changes its state. You can think of a state as
being "on" or "off", "1" or "0", "true" or "false". When the state changes, an "action" can then
be taken. Once the signal has changed state and the action performed, it will not take further
action until the state changes again to prevent a continuous string of actions. For example, if a
switch is turned "on", the lights come on and stay on. They don’t continually go on,on,on…
Once the switch is turned off, the lights can go off, and then they are ready to be turned on again,
etc.
There are three classes of events: Reset, Immediate and Scanned. Scanned events subdivide into
discrete I/O events and analog input events. These are defined in the following paragraphs.
Reset Event
A reset event occurs only once when the MRC-565 powered up or reset, when the event monitor
task is started for the first time, or is stopped - then restarted. It is a well-defined event that does
not need to scan anything in order to determine whether or not a reset has occurred. It occurs
once on each power up or monitor-start. There is also no corresponding end to this event. The
logical end of this event would be power failure or shutdown, but either such event makes the
MRC-565 unable to respond to anything. An action taken on a reset event command will remain
as defined in the command until the MRC-565 is reset again or powered off, or until some other
event changes the action. Stopping the event monitor will not clear the reset event definitions.
Command Event
An immediate action can be triggered by entering a local event command from any port, or by
remote command sent over the RF link. This type of action does not get stored in the event table
and will not be re-issued on power-up or restart. In this way, the operator has the ability to
manually override or control conditions in the field. The event state is considered to be "true" as
soon as the command is entered or received. Once the action is completed, the event state is set
to "false" again.
Scanned Event
Scanned events are tested on a periodic basis by the monitor task. An input signal that would
trigger a scanned event must be repeatedly tested to see if the signal persists at a trigger level
before an event is started. A scanned event is started when a signal remains at (or above or
below) the trigger level for a defined settling duration. When an event is detected by its input
condition persisting at its high state for a settling duration, that event's associated action is
triggered and the monitor task begins looking for the end of the event. The end of an event
occurs when the event remains at a low state for a defined hold-off duration. After the hold-off
duration with the input condition at its low state, the event is enabled to scan for the next event.
For example, if an event is testing the battery voltage to be above 5.0 volts, the action will be
triggered when the voltage is first detected to be at or above 5.0 volts for the entire settling
period. When the voltage goes below 5.0 volts for the hold-off period, it will re-arm the event to