ATM11 - Barometer

ATM11 barometr

Basic description

The ATM10 and ATM11 sensors convert atmospheric air pressure and air temperature, sensed by a semiconductor sensor (ATM10) or a Pt100 precision sensor (ATM11), into a digital signal transmitted to the connected system via the RS485 bus.

Both sensors contain an accurate, temperature-compensated sensor that allows the measurement of atmospheric air pressure in the range of 300 to 1100 mbar with a resolution of 0.01 mbar. The use of a precise sensor with very low temperature drift, excellent linearity and long-term stability, together with microprocessor control of the measuring cycle, ensures the sensing of atmospheric pressure with a very small error (typically <0.5 mbar). In total, ATM sensors contain up to 6 measuring channels that can be transmitted to the connected unit.

Mechanical design

All electronic circuits of the sensor, including the strain gauge pressure sensor itself, are housed in a cylindrical plastic housing with a diameter of only 16 mm and a length of 80 mm. The lower end of the housing is equipped with an industrial 4-pin M12 connector, through which the converter is powered and through which it transmits the measured data to the connected device.

The mechanical design of the sensor allows its placement in the radiation cover RK5 or in the cable gland of the telemetry station. The RK5 radiation cover is especially suitable for the ATM11 sensor, which is supplemented by accurate air temperature measurement using a platinum Pt100 sensor of accuracy class A.

Radiační kryt

The sensor can be supplied with a fixed cable of the required length or equipped with a standard M12 connector.

ATM11 barometer

Measurement of atmospheric air pressure

Both ATM10 and ATM11 sensors use a high-precision sensor from MEAS Switzerland for measuring atmospheric air pressure, which is characterized by very low temperature drift, excellent linearity and excellent long-term stability. The analog signal of the strain gauge bridge inside the sensor is measured by an integrated 24-bit AD converter, which is supplemented by internal calibration coefficients during production. The result is excellent sensitivity and accuracy of measurement, at which a resolution of up to 0.025 mbar can be obtained (this corresponds to a pressure difference of only 20 cm).

The software of the ATM10 and ATM11 sensors performs measurements and subsequent calculations for up to 6 internal measuring channels, which can be transmitted to the connected unit:

Channel K1: Air pressure, range 300 to 1100 mbar, resolution 0.1 mbar

Channel K2: Air temperature measured by a precision Pt100 sensor, accuracy class A (only for ATM11, range -30 to +50 °C, resolution 0.01 °C)

Channel K3: Air temperature measured by ATM sensor (range -30 to +50 ° C, resolution 0.1 °C

Channel K4: Reserve

Channel K5: Air pressure reduced by 500.00 mbar, range 500 to 1150 mbar, resolution 0.025 mbar (the shift was caused by the requirement to archive the high resolution of the sensor and the limited archiving capacity of the connected recording unit, which is max 16 bits per value, ie max. range 0 to 650.00 mbar)

Channel K6: Air pressure converted to altitude, range 300 to 1100 mbar, resolution 0.1 mbar (channel setting requires entering the altitude of the final location in the parameters of the sensor during its production or during its installation in the field)

Air temperature measurement

The RVT11 sensor measures the air temperature with a typical error not exceeding 0.25 °C in the range from -30 °C to +50 °C. In the entire operating range from -50 °C to + 70 °C, the typical temperature measurement error is less than 0.4 °C. High accuracy and stability of measurement allows the use of high resolution of the measured temperature, which can be set by the user in the connected recording unit. The converter works with minimal noise without fluctuations and with a resolution of 0.002 °C.
The RVT10 sensor measures the temperature using a semiconductor sensor with typ. accuracy 1 °C.

Connection of converters via RS485

Both ATM10 and ATM11 converters communicate with the connected recording unit via the RS485 bus under the FINET protocol (Modbus RTU). The communication interface is fully compatible with all telemetry stations of FIEDLER AMS s.r.o. (hydro loggers H1, H2, H3, H7, H40, STELA stations and M4016).

Communication address, baud rates and some other parameters of ATM10, 11 converters are user-adjustable, which allows you to connect several different devices and sensors to existing and newly built RS485 networks.

Technical parameters

Parameter	Value
Number of measuring channels	5 +1 rezervní
Air pressure measuring range	300 to 1100 mbar
Permitted overload	10 to 2000 mbar
Pressure measurement error	<±1,5 mbar (for 25 °C, 750..1100 mbar), <±2,5mbar (for -20..70 °C, 300..1100 mbar)
Long-term stability	typ ±1 mbar / year
Temperature sensor type (ATM11 only)	Pt100 accuracy class A, four-wire connection
Temperature measuring range	-40 °C to +70 °C
Resolution	0,002°C
ATM11 temperature measurement error	typ 0,15+0,001t [°C], max 0,25+0,002t [°C] ATM10: < 0,8 °C for 25 °C, max 2,0 °C in range -20..+70 °C
Measurement time of one channel	<0,1 sec
Output	RS485, connection cable length up to 500 m
Communication protocols	FINET (Modbus RTU), range of adjustable addresses: 1 to 16
Power voltage	Un: 6 to 16 V DC
Dimensions	diameter 15.8 mm, length 84 mm