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Understanding ALTA Sensor Data Logging

ALTA Sensor Data Logging

ALTA sensors offer data logging capabilities to ensure that data recorded by your sensors is not lost in the event of loss of power and loss of radio communication. Current versions of both Alta Sensors and Alta Gateways offer this feature. This article will provide details on the functionality of sensor data logging. It is also important to understand Link Mode when considering sensor data logging.

General sensor message logging behavior

Readings taken on sensor Heartbeat Intervals are logged in the sensor memory in the condition that the sensor has a connection to the gateway, is reporting data, and then loses radio communication with the gateway. Once the sensor is back within range of the gateway’s radio, the sensor establishes a connection and reports current readings. After reconnection, the sensor then starts uploading logged readings in a manner that efficiently manages gateway bandwidth. The sensor will then upload the logged readings over the next series of communications (which may occur outside of the standard Heartbeat Interval). How many subsequent communications depends on the amount of time the sensor was not in range, how frequent the sensor Heartbeat, and therefore how many logged data messages are to be uploaded.

Data logging in Sensors

Current Alta Sensors offer the capability of logging up to 3200 sensor messages. In the event of loss of radio communication to the gateway (whether the sensor is moved out of range, the gateway is powered off, or other scenarios), the sensor will log up to 3200 readings at it’s Heartbeat interval (as long as the Alta sensor firmware is version 14.x.x.x or later). These logged readings will be delivered to the gateway upon restoration of the radio link to the gateway. In the case of many logged data messages, it can take a significant amount of time to upload the data (possibly hours).

Things to consider regarding logged sensor messages
  • The sensor must have had an established connection to the gateway and been reporting data in order to start logging readings upon signal loss.
  • Sensors with firmware 14.x.x.x and later will retain their logged messages even on power loss.
  • Sensors with firmware 14.x.x.x and later do not offer a manner by which to clear logged messages (including power cycle).
  • Sensors with firmware prior to 14.x.x.x will log 512 messages maximum.
  • Once the sensor reaches the maximum logged messages, the sensor will halt logging and no additional readings will be logged (in which case, there may be a gap when logged messages are uploaded to the gateway).
  • Once the sensor’s connection to the gateway is restored, the sensor will relink to the gateway, and start uploading the logged messages.
Uploading logged messages

Once the sensor relinks to the gateway and sends a current reading, the sensor will begin to upload the backlogged data. This will occur in batches, and the devices will manage this upload as to efficiently manage the gateway’s bandwidth. As a result, you will likely see gateway be more active than normal and transmissions that contain more than expected data. If you review the sensor history, you will likely see backlogged data begin to show under the sensor history as it is uploaded.

Note: because of the higher than normal transmission activity, sensor configurations and other activities that require gateway bandwidth may be affected during logged message uploads from extended periods for multiple sensors. It is common to have sensors which do not accept configurations during logged data uploads from any sensors on the network, especially with sensors with firmware 14.x.x.x and earlier.

Factors affecting sensor data logging

The following factors can affect sensor data logging, and should be considered if you find your sensors did not report logged messages.

  • Sensor firmware version
  • Gateway firmware version
  • Environmental factors
  • Network configurations and linking with unexpected gateways


Sensor logging can be a powerful tool to ensure your sensor data is reliable. If you have inquiries related inquiries, feel free to reach out to

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