BHT-Barometric Humidity Temperature (Modbus) (Previously TPH)

TPH‑1™ is a digital sensor that measures air temperature, relative humidity, and barometric pressure. TPH‑1 uses the Modbus RTU protocol to connect to computers, programmable logic controllers (PLCs), some data loggers, and, of course, Dyacon Weather Stations.

Description

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Introduction


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Description

BHT is a high-quality, combination barometric, temperature pressure sensor, and humidity module. All sensing elements are integrated into a single probe and radiation shield. BHT is a low‑power, digital‑output module with a Modbus RTU interface. (More about Modbus.)

BHT is compatible with Dyacon control modules and Modbus host devices, such as programmable logic controllers (PLCs) and personal computers.*

Configuration parameters, such as baud rate, sensor address, and calibration settings, can be programmed through documented Modbus commands. No special programming software is required.

Feature Summary

  • Barometric pressure
  • Air temperature
  • Relative humidity
  • Modbus output
  • Low-power operation
  • Wide input voltage

BHT is a standard component of Dyacon MS‑100 series weather stations.

*Personal computers will require an RS‑485 adapter and appropriate software.

Key Features

Construction

BHT active sensing probe is housed in a compact radiation shield.

Radiation shield material is UV-stabilized PVC, which provides a rugged, low-mass construction that is designed to hold up over many years of use.

Hum-Temp

Temperature and relative humidity data are provided by a precision Swiss sensing element. The best-in-class capacitive sensor is highly accurate to the boundaries of its operational limits. The robust sensor is highly stable in harsh environments and exhibits minimal aging.

Barometric Pressure

A 24-bit ADC digital pressure sensor element has the capability to deliver +/- 1.5 mbar. (As a reference point, that equates to 10 cm of altitude change.)

Data Connection

Power and data are supplied through a 4-wire Modbus RS‑485 connection to a host device. Drawing a 1.4 mA average, BHT is suitable for solar-powered instrumentation systems. Additional sleep options can reduce average current to 60 micro-amps.

Mounting

The BHT mounting system is compatible with standard 1” pipe, PVC, aluminum, or steel.

The horizontal mounting pipe positions the air sensor away from the mass of surrounding structures and equipment that may affect air flow and temperature. The pipe also serves as an air duct for the normal passive aspiration or the aspirator kit.

Accessories

BHT can be used with the Smart-Fan™ aspiration kit for improved performance even in solar power stations. The mounting pipe serves as a remote exhaust, eliminating exhaust recirculation affecting sensor measurements.

Specifications

TEMPERATURE
Range-40°C to 80°C
Resolution0.01°C**
Accuracy (0°C to 60°C)+/- 0.2 K*
Reproducibility+/- 0.1 K
Response Time12 s
Long Term Drift<0.05 K/yr
Sensor TypePTAT

RELATIVE HUMIDITY
Range0% to 100% RH
Resolution0.01% **
Accuracy+/- 1.8% (0% to 80%)*
Reproducibility+/- 0.2% RH*
Hysteresis< +/- 1% RH
Linearity< +/- 1% RH
Response Time12 s
Long Term Drift<0.5% RH/yr
Sensor TypeCapacitive

BAROMETRIC PRESSURE
Range10 mbar to 1300 mbar
Resolution0.065 mbar**
Accuracy+/- 1.5 mbar*
Response Time0.5 ms
Long Term Stability<1 mbar/yr
Sensor TypeMEMS

*Full response range information is available upon request.

**The actual sensing element is highly sensitive (resolution of 0.02%), but message frame reports value in 0.1 increments.

ELECTRICAL
Power Input5 VDC to 24 VDC
Current1.4 mAavg at 12 VDC full run mode†
60 uAavg in sleep mode‡

MECHANICAL
MaterialUV-stabilized, PVC, white
Overall (WxDxH)13.2 cm x 13.4 cm x 13 cm (5.2” x 5.3” x 5.1”)
Cable4 conductor, 24 AWG, stranded
Foil shield w/ drain wire
Outdoor rated cable
Total Weight288 g (10.2 oz)
Weight Shield Only228 g (8.1 oz)

DATA
ProtocolsModbus RTU slave (RS-485)
Half duplex (2-wire)
Min. Request Period50 ms at 19200 bps

TEMPERATURE
Operating Temperature-40°C to 60°C
Storage Temperature-40°C to 80°C

ACCESSORIES
AspirationKIT-ASP-122
Horizontal Mounting KitKIT-TPHMNT

† Continuous full run mode, reading 200 range registers once per second.

‡ Timeout set to 50 or greater. No Modbus activity. See product manual for more information on this function.

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