Instruction Manual
D103621X012
4320
January 2018
35
Advanced Wireless Reporting (Report By Exception and Delayed Triggering)
Report By Exception (RBX) or Triggered Burst Mode allow you transmit data only when a change occurs. When a
triggered burst mode is enabled, a “trigger” variable is identified, and the data is sampled and published at a fast rate
when there is a significant change in the monitored trigger variable. A slower “default” rate is used when the trigger
conditions are not met. This feature results in lower energy consumption by the device, as there are fewer data
transmissions. You can define what is a “significant” change, as well as the values of the fast and default update rates.
To use this feature, configure one of the triggered burst modes. The “triggered” burst modes include: Windowed,
Rising, Falling, and On-Change trigger modes.
D
Windowed
— allows you to define a +/- boundary around the last sampled of the trigger variable. The trigger
variable must change by more than that “window” to trigger the fast update rate.
D
Rising
— the faster updates begin when the value of the trigger variable rises above the trigger level you select.
D
Falling
— the faster updates begin when the value of the trigger variable falls below the trigger level you select.
D
On-Change
— the whole burst message content is monitored for the slightest change.
Any
change initiates the
fast update rate.
Note
On-Change trigger mode is used for messages that contain discrete data. It should not be used on messages that contain floating
point data that dithers as a result of system noise or resolution limitations, such as the temperature variable.
The trigger variable varies with the selected message content. When “Selected Device Variables” is the general burst
message content, the variable that you assign to slot 0 in the Detailed Message Contents is the one monitored against
the trigger conditions. In most cases the assigned trigger variable is one of the process-related variables, i.e., one of
the 3 switch state signals. In other configurations of general message content, the trigger variable is predefined and
can be determined by viewing the configuration data.
Sensor Sample Rate
—If any burst message is being triggered (is not in Continuous mode) a common sensor sample rate
is used for all data acquisition. For battery-powered devices, select a value between 0.5 seconds and the Triggered
Update Rate, in increments of 0.5 seconds.
Normally, the device wakes up to sample the data for a burst message in preparation for each scheduled publishing
event. In some applications it is possible to miss transitions that occur between the update intervals. Delayed
Triggering reduces the possibility of this occurring by defining a faster sample rate for monitoring. The sample rate
should be faster than the published rate. When a trigger condition is detected by the Delayed Triggering mechanism,
the time stamp and data are captured immediately. Publishing of the message is scheduled for the next available
publishing slot. For example; if you have the default update rate set for 1 minute, and the fast update rate set to 8
seconds, enabling Delayed Triggering with a 1/2 second sample rate allows you to detect a trigger event almost as
soon as it occurs. Without Delayed Triggering, transient events that occur
during
the 8 seconds interval are not
detected.
D
Device
Identification
Tag
—enter the HART tag for the instrument (up to 8 characters). The HART tag is the easiest way to distinguish
between instruments in a multi‐instrument environment. Use the HART tag to label instruments electronically
according to the requirements of your application. The tag you assign is automatically displayed when the Field
Communicator establishes contact with the 4320 at power‐up.