The Dwyer RHPX-2SDC0-00 is a duct mount humidity and temperature transmitter from the Dwyer Series RHPX, built around a capacitive polymer humidity sensor rated to ±2% RH across 10% to 90% RH at 25°C (77°F). It reports over BACnet MS/TP or Modbus RTU on an RS-485 network at baud rates from 9600 to 115200, with an on-board 120 Ω termination resistor for end-of-line devices and DIP-switch selection of protocol and network address. The plenum plastic probe carries a hydrophobic filter for duct air streams. The housing is UL 94 V-0 rated to IP66 / NEMA Type 4X, and on-board DIP switches select imperial or metric units.
- Duct-mounted humidity and temperature measurement, installed per the duct mounting procedure in AQ-RHPX-A
- RS-485 trunks where one twisted pair carries humidity, temperature, dew point, enthalpy and absolute humidity from a single device
- Plenum-space installations covered by UL 2043
- Dwyer publishes these Series RHPX applications: air economizers, outdoor humidity and temperature reference, pool room humidity monitoring, building energy management systems, commercial HVAC systems, clean rooms, museums and data centers
Key Features
BACnet MS/TP or Modbus RTU
Protocol is set by DIP switch 9 and the network address by switches 1 through 8. Supported baud rates are 9600, 19200, 38400, 57600, 76800 and 115200. Modbus addresses run 001-247 and BACnet addresses 000-127.
±2% RH Capacitive Polymer Sensor
Humidity sensor accuracy is ±2% at 10% to 90% RH and 25°C (77°F), across a full 0% to 100% measurement range, with 0.1% RH resolution.
Intelligent Serial Configuration
The transmitter can determine baud rate, parity and stop bits automatically from observed Modbus or BACnet serial traffic. Set a valid address, reapply power, and the red LED blinks until a request has been received and processed.
Five Measured and Calculated Values
Relative humidity, temperature, dew point, enthalpy and absolute humidity are all exposed as BACnet analog inputs AI1 through AI9 and as Modbus input registers, in both metric and imperial engineering units.
On-Board 120 Ω Termination
DIP switch 10 connects the internal 120 Ω termination resistor when the transmitter is the end device on the RS-485 segment, removing the need for an external resistor.
UL 2043 Plenum Rated
UL 2043 compliance covers RHPX-XS(D,E)-XX-X plastic probe duct mount without LCD, which includes this model, allowing installation into the plenum space. The unit also carries BTL and CE compliance, and Dwyer qualifies its UL 60335-2-40 listing as meeting UL 60335-2 clause 30.103DV.1 through that same UL 2043 compliance.
Technical Specifications
| Model / SKU | RHPX-2SDC0-00 |
| Sensor Configuration | D — Duct mount with plenum plastic probe and hydrophobic filter |
| Enclosure Size | S — Small enclosure |
| Humidity Measurement Range | 0% to 100% humidity |
| Humidity Sensor Accuracy | ±2%, at 10% to 90% RH and 25°C (77°F) |
| Humidity Sensor | Capacitive polymer |
| Temperature Measurement Range | -40°C to 60°C (-40°F to 140°F) |
| Network Communication | BACnet MS/TP protocol or Modbus RTU |
| Supported Baud Rates | 9600, 19200, 38400, 57600, 76800, 115200 |
| Termination Load | 120 Ω |
| Temperature Accuracy (Solid State Band Gap) | ±0.9°F @ 77°F (±0.5°C @ 25°C) |
| Passive Temperature Sensor | Not available on communicating models |
| Power Requirements | 14 to 35 Vdc or 10 to 32 Vac |
| Wiring Connection | Removable 5P terminal block, 18 AWG maximum |
| Resolution | Relative humidity 0.1%; temperature 0.1°F/°C; absolute humidity 0.1 g/m3 |
| Additional Calculations | Absolute humidity 0 to 50 g/m3 or 0 to 3000 lb/mmcf; dew point -75°C to 60°C (-102°F to 140°F); enthalpy -40 to 411 kJ/kg or -17 to 177 Btu/lb |
| Operating Temperature Range | -40°C to 60°C (-40°F to 140°F) |
| Storage Temperature | -40°C to 70°C (-40°F to 158°F) |
| Display | None on this model |
| Electrical Entry | 1/2 in NPS thread, cable gland included |
| Enclosure Material | UL 94 V-0 |
| Enclosure Rating | IP66, NEMA Type 4X |
| Duct Installation | 1 in diameter duct hole; four #8 x 1/2 in pan head sheet metal screws |
| Product Weight | 198.4 g (0.44 lb), duct configuration |
| Compliance | BTL, CE, UL 2043. UL 60335-2-40 per Dwyer footnote: meets UL 60335-2 clause 30.103DV.1 through UL 2043 compliance. |
| Warranty | 5 year limited warranty |
Documentation
Related Products
Frequently Asked Questions
Reading the Dwyer order code left to right: RHPX is the series, 2 is 2% RH accuracy, S is the small enclosure, D is Duct mount with plenum plastic probe and hydrophobic filter, C is the bacnet ms/tp or modbus rtu communications, 0 is no passive temperature sensor, and 00 is the cable length option.
No. The two-line alphanumeric display is a separate -LCD option on the Series RHPX order code.
No. DIP switch 9 selects one protocol or the other. BACnet MS/TP and Modbus RTU are mutually exclusive on this transmitter.
No. Passive temperature sensors are available on analog models only. If you need a resistive temperature output, order an analog RHPX with a passive temperature sensor code.
Yes. DS-RHPX Rev.1 lists RHPX-XS(D,E)-XX-X plastic probe duct mount without LCD under its UL 2043 compliance footnote, and RHPX-2SDC0-00 falls in that group.
No. Dwyer states the Series RHPX requires no routine maintenance, is not field serviceable, and cannot be repaired. Field repair should not be attempted and may void the warranty.
5 Year Limited Warranty. The Dwyer Series RHPX carries a five year limited warranty as published on the Dwyer Series RHPX catalog page. Warranty and return handling follow the Terms and Conditions of Sale published by Dwyer Instruments, LLC. Contact customer service for a Return Materials Authorization (RMA) number before shipping any product back for repair, and include a brief description of the problem plus any application notes.
The Series RHPX requires no routine maintenance, is not field serviceable, and cannot be repaired. Field repair should not be attempted and may void the warranty.
ZOT Supply is an authorized DwyerOmega distributor. Warranty support is handled through ZOT Supply at sales@zotsupply.com or 855-825-2811.
- Sensor Type:
- Duct
- Humidity Element:
- 2%
- Series:
- RHPX
- Supported Protocols:
- BACnet/Modbus
- Temperature Element:
- Solid State Band Gap
- Display:
- No Display
- Enclosure:
- NEMA 4X Enclosure
- CO2 Element:
- None
- Material:
- Plastic
