Short answer: Every 4 seconds.
Long answer: There are two relevant metrics for understanding Samsara sensor response rate: sampling frequency (how frequently sensors record data) and update frequency (how frequently sensors send recorded data to the cloud).
- Sampling frequency: Every Samsara sensor samples data every 4 seconds.
- Update frequency: Sensors dynamically adjust their reporting interval based on how quickly sensor readings are changing. If sensors detect a rapid change, they will report to the cloud (making the changes visible to the operator) more immediately. If sensor readings are relatively constant, the sensors will buffer and batch their updates to maximize battery life. In practical applications, this buffering should be unnoticeable.
When change occurs, sensors update immediately over the Samsara gateway's persistent connection to the cloud (assuming the sensor is in range of a connected gateway.)
As a result, changes in sensor readings are typically sent to the cloud and reflected in the dashboard in a matter of seconds.
Find more information on EM21 and EM22 sensor basics here.