Sigfox WSSFCB-NH3, Руководство пользователя

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7
The node does not send RF and
the RF module is hot
Insert the battery in the
wrong direction
Electronics got problem
Check battery polarity
8 RSSI is weak and often loses data
Distance between Node
and Base station is far or
there are many
obstructions
Connection to Antenna
problem
Check the location of
Sigfox node and distance
to the base station
Check the antenna
connector in the PCB
The output value of NH3 is calculated from the formula: Y= AX + B
Where:
X = measured value of NH3 from sensor and electronics circuit
Y = output value of NH3 which is sent by the Uplink
A: Constant_A at address 278 in Memmap of sensor
B: Constant_B at address 280 in Memmap of sensor
The default values are: A = 1 and B = 0 ==> Y = X
After a period of time of working the sensor output will be drifted about < 1% of the reading value per month.
So depending on what accuracy you require, you can define how long the sensor needs to be re-calibrated again.
For general application, the cycle of calibration would be 3 or 6 months. For the highest accuracy, the cycle would be 1
or 2 months.
To re-calibrate the sensor, you need to re-calculation the new values of A and B. How can it be done?
By applying the standard Zero and Span Gas. Please follow these steps:
Zeroing can be done in 1 of 2 ways as below:
- Pure air can be used as a Zero standard for NH3 calibration. Simply place the sensor in a clean environment with
pure air. The ambient temperature should be from 20 to 25 oC.
- Or using high purity Nitrogen gas (99.999%) as a zero standard gas. Attach the calibration cap into the sensor and
turn on the Valve to provide the N2 flow into the sensor.
Waiting for the zero gas to enter completely into the sensor for at least 15 minutes, then using the magnet key to
activate the SW1. This action will force the sensor to send the new measured data to the Sigfox backend, you got the
measured value Y_o.
As the sensor has the maximum measurement range is 100ppm, you can use any standard NH3 gas cylinder with a
concentration from 25ppm to 100ppm for calibration. Please follow the steps below:
- Attach the calibration cap into the sensor and turn on the Valve of the cylinder to provide the span gas flow into the
sensor.
Waiting for the span gas to enter completely into the sensor for at least 5 minutes, then using the magnet key to
activate the SW1. This action will force the sensor to send the new measured data to the Sigfox backend, you got the
measured value Y_s.
10. Sensor calibration
10.1 Apply zeroing gas standard:
Before applying zeroing process, please do this step first: place the sensor in a Pure air environment from 20-25
oC in at least 1h. The sensor must be powered and running at the time.
10.2 Apply span gas standard: