Manage Data Stream Thresholds

You can configure thresholds for data sample values for data streams.

threshold is a user-defined range of data sample values. A threshold is used for setting up automated alert and notification actions. A threshold can be set only for data streams; it cannot be set for virtual streams, technical streams, and event streams. Data stream thresholds are configured for each data stream individually. 

Both a data stream threshold and its alert action are configured in the UI. The configurations are downloaded automatically to the device during the next transmission. The information is stored on the device so that it can execute the appropriate commands immediately when the threshold is exceeded. Each data stream type - serial, analog, and digital - can have a maximum number of thresholds configured for it. 

Thresholds are configured by defining the upper limit value of a range. The upper limit of the previous range (or lower limit of sensor, if this is the first threshold being defined) is the lower limit of the range being configured. Let’s say you want to configure thresholds for a temperature sensor that can measure between 0°F and 250°F. The first range begins at 0°F, and you set the threshold (upper limit of the range) to be 90°F. This range is defined as "Normal" with no alert action required. The next range automatically begins at  90°F, and you define the threshold (upper limit of the range) to be 120°F, and designate the range as "Hot". This range will have an alert action. The final range automatically begins at 120°F, and you define the threshold (upper limit of the range) to be 250°F, and designate the range as "SuperHot". This range will have an alert action. 

A key feature of the device is the ability to configure multiple thresholds as described above for any data stream, and to specify which actions to take when data samples exceed each threshold. Actions might be modifying the sampling or transmission frequency, or sending email and/or SMS alerts to certain users. For example, you can specify sending alerts when data samples cross a threshold. Another example might be one data stream triggering the sampling of a different data stream. Each individual data stream can be configured with up to four threshold ranges.

One of the alert actions is changing the transmission interval. A transmission interval defines how often the device transmits the data. You can designate that when a device exceeds a threshold, it will automatically change its pre-defined transmission mode: Normal, Event, and Emergency. 

Another alert action is to change the sampling interval of the stream. If you configure the alert to change the sampling interval, then the new sampling interval affects all streams in the same sample group. For example, when stream A reaches a threshold and tells the sensor to sample every minute, all streams in stream A's sample group will begin to sample every minute rather than just the specific stream that exceeded its threshold. 

The False Alarm Threshold helps to ensure that threshold alerts are not sent during short data spikes. For example, if you set this value to 120 seconds, that means that no alert actions will be implemented if stream samples are within the threshold range for less than 2 minutes.