Our COMET range of temperature, humidity, CO2 and pressure transmitters communicates over an RS485 (Modbus RTU) serial output — industrial instruments built for continuous monitoring in laboratories, cleanrooms, server rooms, greenhouses and process areas, not development boards or hobbyist modules.
RS485 is a multi-drop serial interface — unlike point-to-point RS232, up to 32 devices can share one twisted-pair bus over cable runs of several hundred metres, each addressed individually over Modbus RTU. That makes it the practical choice for monitoring several rooms or zones from a single BMS, PLC or SCADA controller.
Our COMET range of temperature, humidity, CO2 and pressure transmitters communicates over an...
Ambient Temperature transmitter with RS485 output…
Barometric pressure transmitter – RS485 int…
RH+T+Tdp outdoor, indoor probe, RS485 interface
Temperature and humidity duct mount transmitter w…
Temperature and humidity duct mount transmitter w…
Temperature and humidity bar type transmitter wit…
Temperature and humidity transmitter with externa…
Compressed air RH+T transmitter with RS485 output…
Temperature transmitter with RS485 interface
CO2 concentration transmitter with RS4…
CO2 concentration transmitter with RS4…
Every COMET RS485 transmitter ships with a traceable calibration certificate, a 3-year warranty and free TSensor configuration software — industrial-grade instrumentation, not a $10 breakout board. Several models add relay outputs for local alarm switching alongside the RS485 feed.
Choose by measured parameter and whether you need relay outputs for local alarms (H-series) or duct/compressed-air mounting (D/P-suffix models).
Need a shorter, simpler point-to-point link instead? See our RS232 range.
Prefer a networked or wireless output? See Ethernet, PoE or WiFi Sensors.
We stock and calibrate the full COMET range in Australia, with NATA-accredited calibration certificates included.
COMET RS485 transmitters are complete industrial instruments — a calibrated sensor element, signal conditioning and an RS485/Modbus RTU output in an IP65-rated housing, backed by a traceable calibration certificate and 3-year warranty. Low-cost RS485 'sensor modules' sold on Amazon or AliExpress are typically uncalibrated breakout boards intended for hobbyist or development use.
RS485 supports multi-drop networking — up to 32 devices sharing one twisted-pair bus over cable runs of several hundred metres, each individually addressed over Modbus RTU. RS232 is point-to-point — one transmitter to one device, over a shorter cable run (typically up to ~15m). See our RS232 range for single-device, shorter-distance installations.
Yes — the COMET RS485 range communicates via Modbus RTU (most models also support the Advantech ADAM-compatible protocol), letting them integrate directly with building management systems, PLCs and SCADA platforms that already read Modbus.
Up to 32 devices on a single RS485 bus in a standard configuration, each with its own Modbus address, reporting back to one controller or gateway — the key advantage over a point-to-point RS232 link.
RS485 is rated for cable runs of up to roughly 1,200 metres at lower baud rates, far exceeding RS232's practical ~15m limit — the reason it's the preferred choice for multi-zone or multi-building monitoring.
The H-series (H0430 temperature, H3430/H3431 temperature & humidity, H4431 Pt1000 temperature, H5421/H5424 CO2, H6420 temperature/humidity/CO2, H7430 temperature/humidity/pressure) all add two relay outputs alongside RS485, for driving a local alarm, fan or damper directly from the transmitter.
Yes — the range includes combined temperature & humidity, temperature/humidity/CO2, and temperature/humidity/pressure models, duct-mount and compressed-air variants, as well as single-parameter temperature, pressure and CO2 transmitters.
Yes. Pacific Sensor Technologies holds local stock, ships Australia-wide. With our own NATA-accredited lab, service and recalibration don't depend on overseas turnaround.
