Atmospheric pressure sensor BAR

0÷2Vdc, 4÷20mA or RS485 / Modbus | 800÷1100 hPa | Piezoresistive | < 0.4 hPa @ 20°C | 120 x 80 x 55mm | 10÷30Vdc | IP65

Manufacturer: Nesa
Category: Meteorology – Climatology, Pressure, Atmospheric pressure, SENSORS

The NESA BAR is an electronic barometer for measuring atmospheric pressure, with a piezoresistive transducer, IP65 plastic housing, and construction according to WMO standards. Typical range 800–1100 hPa and accuracy < 0.4 hPa @ 20 °C.

Output: 0-2Vdc (BAR-A), 4-20mA (BAR-B), or RS485/Modbus (BAR-C). Supplied with calibration report. For weather stations, environmental monitoring systems, and measurement campaigns.

Key points

Typical range 800÷1100 hPa; other range 500÷1100 hPa
Accuracy < 0.4 hPa @ 20 °C, sensitivity and resolution 0.05 hPa
Piezoresistive transducer, response time < 2 s
Output 0÷2Vdc, 4÷20mA or RS485 / Modbus
10÷30Vdc, < 0.1 W, reverse polarity and transient protection
IP65, -40 ÷ +60 °C, 270 g

Technical Frequently Asked Questions

What exits does the BAR have?

BAR-A: 0÷2Vdc = 800÷1100 hPa. BAR-B: 4÷20mA = 800÷1100 hPa, not self-powered. BAR-C: RS485 / Modbus (Standard ID 013).

What parameters does the digital output have?

RS485 half-duplex at 9600 baud, parity N, 8 data bits and 1 stop bit. Modbus RTU only with function 0x03, 32-bit IEEE754 floating-point value at addresses 40002-40003. Serial protocol request command: 013CR.

What does each kit include?

Calibration report and a cable with terminal block or PS2 connectors. The cable can also be ordered separately: CS05, CS10 or CSxx.

How do I order it?

Sensor (BAR), output (A, B or C), sensor-datalogger cable (05, 10 or xx, length in meters to be specified) and bracket (SSU, L = 700-750 mm, for outdoor use only). Manufacturer's example: BAR B 10 SSU.

Properties

Feature	Specification
Measurement and operating principle
Measured magnitude	Atmospheric pressure
Typical range	800÷1100 hPa
Another range	500÷1100 hPa
Transducer type	Piezoresistive
Precision	< 0.4 hPa @ 20 °C
Sensitivity	0.05 hPa
Resolution	0.05 hPa
Response time	< 2 s
Regulatory compliance	WMO; CE
Output signals and interface
Exit sign	0÷2Vdc (A); 4÷20mA (B); RS485/Modbus(C)
Exit A	0÷2Vdc = 800÷1100 hPa [hPa = (V·300)/2 + 800]
Exit B	4÷20mA = 800÷1100 hPa, not self-powered [hPa = 300·(mA – 4)/16 + 800]
Output impedance	100 Ω
RS485 interface (half-duplex)	9600 baud, N parity, 8 data bits, 1 stop bit
Serial protocol	Request command 013CR (ID 013); the response is the measured value in the programmed engineering unit
Modbus RTU	Function 0x03 (Read Holding Register) only; 32-bit IEEE754 floating-point value in two 16-bit registers, addresses 40002-40003
Power supply, environment, and mechanical data
Food and consumption	10÷30Vdc, < 0.1 W
Protections	Polarity reversal and transients
Operating conditions	-40 to +60 °C
Box	Plastic (ABS), IP65
Dimensions	120 x 80 x 55 mm (see drawing)
Weight	270 g
Calibration	Functional test by comparison with a reference precision barometer; comes with calibration report
Supply	Includes cable with terminal block or PS2 connectors and calibration report

Reference	Configuration
BAR-ABARA	Output signal: 0÷2Vdc · Supply: 800÷1100 hPa, compliant with WMO, with calibration report; also available with separate cable (CS05, CS10, CSxx)
BAR-BBARB	Output signal: 4÷20mA · Supply: 800÷1100 hPa, compliant with WMO, with calibration report; also with separate cable (CS05, CS10, CSxx)
BAR-CBARC	Output signal: RS485 / Modbus · Supply: 800÷1100 hPa, compliant with WMO, RS485 / Modbus or RS485 with serial protocol, standard ID 013, with calibration report; also with separate cable (CS05, CS10, CSxx)