OPTICAL RAIN GAUGE
The bucket was always the problem
Infrared optical rainfall measurement, with nothing that tips
A tipping bucket is a mechanism in a place nobody visits. It sticks, it blocks, it drifts out of calibration, and none of that announces itself. The rainfall record just quietly stops being right.
Infrared optical rain gauge
Solid-state, no moving parts
5% accuracy, 0 to 200 mm/hr
0.1 mm resolution, one pulse per 0.1 mm
Tipping-bucket pulse output
Drops into existing systems
24-month warranty
Supplied with connector and manual
- Infrared opticalSolid-state rainfall measurement, no moving parts
- 5% accuracy0 to 200 mm/hr at 0.1 mm resolution
- Tipping-bucket pulse outputOne pulse per 0.1 mm, read by existing loggers unchanged
- Pairs with your stationMaxiMet GMX550 and GMX551, and MetConnect
The measurement problem
A rain gauge that fails silently
Leaves, insects and debris are the classic tipping bucket failure, and the classic thing about it is that the gauge keeps reporting. It reports less rain than fell, and nothing in the data says so until somebody climbs the mast.
TruMet PW100 removes the mechanism. Rain is measured optically, using infrared light, so there is nothing to tip, nothing to empty and nothing to stick.
Every 0.1 mm of rain produces one pulse, exactly as a tipping bucket produces one tip. Any logger or station expecting a tipping bucket input reads TruMet without changes to the wiring convention or the data record.
Nothing to tip
Optical infrared measurement, with no moving parts.
Tipping-bucket pulse
One pulse per 0.1 mm, the same as one tip.
Less prone to blockage
Less susceptible to debris, leaves and insects.
IP66 housing
UV-stabilised thermoplastic, 0.67 kg.
The model
One optical rain gauge, wired like a tipping bucket
TruMet PW100 is a rainfall sensor, not a weather station. It complements a station, or any logger expecting a tipping bucket input, rather than replacing one.
TruMet PW100
When a rainfall record matters and the mast is somewhere nobody wants to visit. Replaces a tipping bucket on the same input.
No single TruMet PW100 does all of that. Our team can suggest a pairing.
A pulse output, one per 0.1 mm, replicating a conventional tipping bucket gauge, through an 8-way M12 connector. If you need a digital interface such as SDI-12 or Modbus, ask us rather than assuming, because the pulse output is what the datasheet describes.
Where it pairs
It is a rainfall sensor, not a weather station
TruMet connects wherever a tipping bucket input exists. Within the MaxiMet range that is the GMX550 and GMX551 only. Other MaxiMet models have no such input, so they do not pair with TruMet.
GMX550 and GMX551 pair. GMX603 has it built in.
- GMX550 and GMX551 have a tipping bucket input for the TruMet pulse output
- GMX551 adds solar radiation to the GMX550 measurement set
- GMX603 carries TruMet rainfall integrated, so it is the built-in option rather than a pairing
Through the contact closure rain input
- Both MetConnect One and MetConnect THP pair with TruMet
- TruMet connects to the contact closure, tipping bucket rain input
- The same route any third-party logger expecting a tipping bucket takes
Not sure which fits? Make an enquiry
Choosing between them
Which station, in one line each
TruMet replaces a tipping bucket rather than competing with a weather station. The question is what it connects to. Pairing was confirmed with Product on 25 June 2026: if a MaxiMet is not named here, treat it as not supported rather than assuming.
| Specification | PairsGMX550 | PairsGMX551 | Built in, do not pairGMX603 | PairsMetConnect |
|---|---|---|---|---|
| How TruMet connects | Tipping bucket input | Tipping bucket input | TruMet rainfall integrated | Contact closure rain input |
| Station measures | Wind, T/H/P, rainfall | Wind, T/H/P, rainfall, solar | Wind, T/H/P, high-accuracy rainfall | T/H/P, wind on One, plus your own sensors |
| Rainfall | Optical or tipping bucket | Optical or tipping bucket | Optical, 0 to 200 mm/hr, 5% or better | Via the rain input |
| Solar radiation | No | 0 to 1600 W/m² | No | No |
| Weight | 0.7 kg | 0.8 kg | 1.1 kg | 3.0 kg hub box |
| Datasheet | Datasheet | Datasheet | Datasheet | Datasheet |
TruMet vs a tipping bucket
What changes when the mechanism goes
The output is deliberately identical. Everything behind it is not. A tipping bucket relies on a mechanism that tips and empties. TruMet measures optically, so there is no mechanism to wear or stick between service visits.
Debris, leaves and insects are the classic tipping bucket failure. TruMet is less susceptible to debris blockage, which matters most on remote sites where nobody visits the mast often.
The technology
Infrared, across a 66 by 20 mm surface
Rain falling through a 66 by 20 mm measurement surface is detected optically, and the sensor converts what it sees into rainfall depth.
It measures liquid precipitation from 0 to 200 mm per hour, to 5 per cent, with a resolution of 0.1 mm. Every 0.1 mm of rain produces one pulse, exactly as a tipping bucket produces one tip.
Rainfall measurement without moving partsSee what it connects to
Deployment
Built to be left alone
The housing is UV-stabilised thermoplastic, rated IP66, weighing 0.67 kg. It fits a 44.45 mm pole or mast and connects through an 8-way M12 connector. Operating temperature runs from -35 to +70 °C, and storage from -40 to +70 °C.
With no tipping mechanism there is no bucket to clear or level between visits. Service intervals and any cleaning regime for the optical window are covered in the user manual.
- Fits a 44.45 mm, or 1.75 inch, pole or mast
- Supplied with the sensor, a mating connector and the user manual
- 24 month warranty as standard
Drops into existing systems
One pulse per 0.1 mm into any logger already wired for a tipping bucket rain input, with no rework to the wiring or the data record.
See where it pairs →Where a tipping bucket still wins
TruMet measures liquid precipitation only, over a measurement temperature range of 0 to +70 °C. Sites that see snow or hail need a different sensor for those periods.
View specifications →One thing to confirm
The 5 per cent accuracy figure is from the released datasheet, TruMet PW100 Iss 1. Ask us for the current issue before you write it into a specification.
Download the datasheet →Applications
Where rainfall has to keep arriving
The common factor is a rainfall record that matters and a mast nobody wants to visit.
HydrometeorologyTruMet reports intensity from 0 to 200 mm per hour at 0.1 mm resolution, and its pulse output matches the tipping bucket record the network already holds, so long series stay comparable.Catchment and hydrometeorology →
Flood monitoringFlood warning depends on gauges that keep reporting during the heaviest rain. TruMet covers 0 to 200 mm per hour, is rated IP66 and has no tipping mechanism to jam or lag.Flood warning and water level →
Environmental monitoringLong-running environmental sites need instruments that survive unattended. TruMet is IP66, UV-stabilised thermoplastic and operates from -35 to +70 °C.Research and environment →
AgricultureGrowers need dependable rainfall figures for scheduling and record keeping. TruMet resolves 0.1 mm, mounts on a 44.45 mm pole and has no tipping mechanism to clear.Agriculture →
Water managementCatchment, reservoir and drainage teams already run tipping bucket inputs. TruMet delivers one pulse per 0.1 mm into that same input, so gauges swap site by site.Drainage, SUDS and attenuation →
Infrastructure and solarSolar farms and infrastructure projects put gauges where nobody wants to go. Less susceptibility to debris blockage means longer runs between visits.Solar site monitoring →Technical specification
TruMet PW100 technical specification
| Specification | TruMet PW100 |
|---|---|
| Measurement type | Optical, infrared |
| Precipitation type | Liquid precipitation only |
| Intensity range | 0 to 200 mm/hr |
| Accuracy | 5% |
| Resolution | 0.1 mm per pulse |
| Measurement surface area | 66 by 20 mm |
| Output | Pulse, one per 0.1 mm, replicating a tipping bucket |
| Construction | UV-stabilised thermoplastic |
| Mounting | 44.45 mm, or 1.75 inch, pole or mast |
| Weight | 0.67 kg |
| Connector | 8-way M12 |
| Protection class | IP66 |
| Operating temperature | -35 °C to +70 °C |
| Measurement temperature | 0 °C to +70 °C |
| Storage temperature | -40 °C to +70 °C |
Figures are quoted from the released datasheet, TruMet PW100 Iss 1. Power supply, the electrical rating of the pulse output and the M12 pin-out are held in the user manual rather than here. Ask for the current issue before writing any figure into a specification.
See it work
Rainfall measurement, in about a minute
Seven short films on what changes when the tipping bucket goes. Each one answers a question engineers ask before they specify.
Modernise without rebuilding
The hidden cost of changing sensors
Density matters. So does realism.
Extreme rainfall exposes mechanical limits
Operational proof matters
The future of rainfall monitoring
Real-time rainfall measurement
Prefer to watch them together? Watch them all on the Gill Group channel
Accessories
TruMet PW100 accessories
Cables, mounting and set-up kit for TruMet PW100, including the cable that pairs it with a MaxiMet.
Cables
- Power and comms cable, 2 m, M12 fitted
- Power and comms cable, 5 m, M12 fitted
- Power and comms cable, 10 m, M12 fitted
- Power and comms cable, 20 m, M12 fitted
- Integration cable to MaxiMet GMX550 or GMX551, 20 m
Connectors
- M12 connector, 8 way, field wireable
Mounting
- Bracket for wall mounting or pole clamping
- Support tube, 0.5 m
Set-up and configuration
- M12 to RS485 configuration cable
Order accessories with your sensor or on their own. Quote the part number when you get in touch.
Technical resources
Everything you need to specify TruMet PW100
Questions
Frequently asked questions
Does TruMet measure snow or hail?
No. TruMet measures liquid precipitation only, and its measurement temperature range is 0 to +70 degrees Celsius. The unit itself operates from -35 to +70 and stores from -40 to +70, so cold will not damage it, but rainfall is what it reports.
How accurate is it?
Accuracy is 5 per cent across an intensity range of 0 to 200 mm per hour. Resolution is 0.1 mm and the measurement surface area is 66 by 20 mm. Those figures come from the released datasheet, TruMet PW100 Iss 1.
Can it replace an existing tipping bucket?
Yes, that is the design intent. TruMet gives one pulse per 0.1 mm, which is exactly what a tipping bucket gives per tip. Anything already expecting a tipping bucket rain input reads TruMet without changes to the logger, the wiring convention or the data record.
Which MaxiMet weather stations does it pair with?
Within the MaxiMet range, the GMX550 and GMX551 only. They are the two models with a tipping bucket input for the TruMet pulse output. GMX603 is different: it carries TruMet rainfall integrated, so it is the built-in option rather than a pairing.
Does it work with MetConnect?
Yes. MetConnect pairs with TruMet through its contact closure, tipping bucket rain input. That is the same route any third-party logger takes. TruMet is a rainfall sensor rather than a full weather station, so it complements a station rather than replacing one.
How is it mounted, and what is in the box?
TruMet fits a 44.45 mm, or 1.75 inch, pole or mast and weighs 0.67 kg. It connects through an 8-way M12 connector. The box contains the optical precipitation sensor, a mating connector and the user manual.
What is it made of, and how well is it sealed?
The housing is UV-stabilised thermoplastic and the protection class is IP66. Operating temperature is -35 to +70 degrees Celsius and storage is -40 to +70. The combination is aimed at long unattended deployments outdoors, where a mechanical gauge would need regular attention.
What warranty does it carry?
TruMet PW100 carries a 24 month warranty. Because there are no moving parts, there is no tipping mechanism to service or recalibrate over that period. Service intervals and any cleaning regime for the optical window are covered in the user manual.
What does the output look like?
A pulse output, one per 0.1 mm, replicating a conventional tipping bucket gauge. If you need a digital interface such as SDI-12 or Modbus, ask us rather than assuming, because the pulse output is what the datasheet describes.
Have an application to discuss?
Speak to our team
Tell us what you need to measure, where and under what conditions. We’ll help you work out the appropriate approach.
Enquiring about TruMet PW100
- Our team replies. Not an account manager, and not a queue.
- We aim to respond in one working day. Monday to Friday.
- No obligation. Plenty of these end with us saying it is not our product.