Synchronizing the Sensor Sampling Times

You can configure a sample group of devices to do sampling that is synchronized with your device's clock.

By default, sampling is not synchronized with the device's clock. Rather, after the device reboots, sampling is done according to the value of the sampling interval (group_sample_interval_sec). Devices typically reboot at different times. As a result, sampling of multiple devices is not done at the same time.  
When a group of devices are synchronized with the device's clock, all devices in the group do sampling at the same time according to the sampling interval. Every time the device wakes up the sensor to take a sample, the device checks its time against the clock and realigns itself, if needed.


To synchronize devices:

1. Ensure all of the sensors belong to the same group - either group 1 or 2 - by doing these steps:

a. Click Devices in the left pane.

b. In the Sites Tree pane, click the device name.

c. In the right pane, click the Configuration tab.

d. Click SampleGroup > GROUP.  Select the group that the sensors are in.

2. For each sensor, do the following steps in the appropriate GROUP:

a. Click group_sample_interval_type. Click the current value of group_sample_interval_type, and then click Set Setting.

b. In the Set Setting window, select INTERVAL_SYNCED from the drop-down list.

3. Save the configuration changes, and then validate that the device rebooted by doing the following steps:

a. Click Devices in the left pane, and then select the device in the Sites Tree pane.

b. In the right pane, click the Commands tab. You will see a Reboot command after a few seconds.

c. If no Reboot command is displayed, click Actions > Reboot in the Device Information pane to manually reboot the device.

 Both the configuration changes and the reboot will take effect after the device contacts the server.

The device will reboot 2 minutes after the next transmission and will synchronize its time with the clock. At reboot, the sensors associated with the group will take samples in time intervals that are offset from the top of the hour.

For example, if reboot occurs at 17:45 and the sampling interval is set for every 10 minutes, all sensors in the group will sample at 18:00 (the top of the hour) and every 10 minutes thereafter.

To expedite the next transmission, you can swipe the magnetic activator key over the embossed logo on the face of the device. The device will go into calibration mode, and thereby force the taking of a few samples and immediate transmission.