Description
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 |
| Resolution | 0.01°C** |
| Accuracy (0°C to 60°C) | +/- 0.2 K* |
| Reproducibility | +/- 0.1 K |
| Response Time | 12 s |
| Long Term Drift | <0.05 K/yr |
| Sensor Type | PTAT |
| RELATIVE HUMIDITY | |
|---|---|
| Range | 0% to 100% RH |
| Resolution | 0.01% ** |
| Accuracy | +/- 1.8% (0% to 80%)* |
| Reproducibility | +/- 0.2% RH* |
| Hysteresis | < +/- 1% RH |
| Linearity | < +/- 1% RH |
| Response Time | 12 s |
| Long Term Drift | <0.5% RH/yr |
| Sensor Type | Capacitive |
| BAROMETRIC PRESSURE | |
|---|---|
| Range | 10 mbar to 1300 mbar |
| Resolution | 0.065 mbar** |
| Accuracy | +/- 1.5 mbar* |
| Response Time | 0.5 ms |
| Long Term Stability | <1 mbar/yr |
| Sensor Type | MEMS |
*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 Input | 5 VDC to 24 VDC |
| Current | 1.4 mAavg at 12 VDC full run mode† 60 uAavg in sleep mode‡ |
| MECHANICAL | |
|---|---|
| Material | UV-stabilized, PVC, white |
| Overall (WxDxH) | 13.2 cm x 13.4 cm x 13 cm (5.2” x 5.3” x 5.1”) |
| Cable | 4 conductor, 24 AWG, stranded Foil shield w/ drain wire Outdoor rated cable |
| Total Weight | 288 g (10.2 oz) |
| Weight Shield Only | 228 g (8.1 oz) |
| DATA | |
|---|---|
| Protocols | Modbus RTU slave (RS-485) Half duplex (2-wire) |
| Min. Request Period | 50 ms at 19200 bps |
| TEMPERATURE | |
|---|---|
| Operating Temperature | -40°C to 60°C |
| Storage Temperature | -40°C to 80°C |
| ACCESSORIES | |
|---|---|
| Aspiration | KIT-ASP-122 |
| Horizontal Mounting Kit | KIT-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.
