7
5.1 ActiveThreshold and InActiveThreshold
Formula
Active Threshold (or InActiveThreshold) =
Critical value ÷
9.8
÷
0.0625
* The gravitational acceleration at standard atmospheric pressure is 9.8 m/s
2
* The scale factor of the threshold is 62.5 mg
Active Threshold
Active Threshold can be changed by ConfigureCmd
Active Threshold range is
0x0003-0x00FF
(default is 0x0003);
InActive Threshold
InActive Threshold can be changed by ConfigureCmd
InActive Threshold range is
0x0002-0x00FF
(default is 0x0002)
Example
Assuming that the critical value is set to 10m/s
2
, the Active Threshold (or InActive Threshold) to be set is
10/9.8/0.0625=16.32
Active Threshold (or InActiveThreshold) to be set integer as 16.
Note: When configuration, ensure that the Active Threshold must be greater than the InActive Threshold.
5.2 Calibration
The accelerometer is a mechanical structure that contains components that can move freely.
These moving parts are very sensitive to mechanical stress, far beyond solid-state electronics.
The 0g offset is an important accelerometer indicator because it defines the baseline used to measure acceleration.
After installing R718EC, users need to let the device rest for 1 minute, and then power on. Then, turn on the device and wait for
the device to take 1 minute to join the network. After that, the device will automatically execute the calibration.
After calibration, the reported three-axis acceleration value will be within 1m/s
2
.
When the acceleration is within 1m/s
2
and the speed is within 160mm/s, it can be judged that the device is stationary.
5.3 Example of data configuration
FPort
：
0x07
Bytes
1
1
Var(Fix =9 Bytes)
CmdID
DeviceType
NetvoxPayLoadData
CmdID
– 1 byte
DeviceType
– 1 byte – Device Type of Device
NetvoxPayLoadData
– var bytes (Max=9bytes)
