The control decision
is made on the weather outside
Reference weather measurement outside the structure and non-contact position feedback on the vents and screens inside it, both built to keep working through years of humidity and constant cycling.
Two things fail, and both fail slowly
Protected cropping control acts on outside conditions. Vents open against wind and rain, screens move with light and temperature, and heating responds to the external demand, so the outside reference is the input to almost every decision the system makes.
If that reference drifts, nothing alarms. The structure simply runs slightly wrong for a season, and the cost appears as crop quality and energy use rather than as a fault.
The actuator feedback has the same problem in reverse. A vent that reports fully closed while sitting slightly open is an energy leak nobody is looking for, and the position sensor telling that story lives in humidity and cycles thousands of times a year.
One holding. Multiple measurement points.
A farm is not one measurement environment.
Wind at the field boundary can be different from the regional forecast. Conditions inside a grain store are different from those outside it. Water levels change with use and rainfall. Machinery develops wear while the rest of the operation continues around it.
Spray application and drift
Whether you can spray is a wind decision, and the record of that decision is the thing an inspector or a neighbour asks to see.
- MaxiMet GMX500 wind, temperature, humidity and pressure in one unit
- WindSonic 60 0 to 60 m/s, 0.5 kg, mounts on the sprayer
- MaxiMet GMX200 wind only, 0.5 kg, for a field-edge mast
Field weather station
The farm and the nearest official station are usually tens of kilometres and one valley apart, and the decisions are made on the farm.
- MaxiMet GMX551 wind, T, H, P, solar and rainfall in one housing
- MetConnect THP Pt100 and analogue inputs for soil probes
- MaxiMet GMX550 wind, T, H, P and rainfall without solar
Irrigation scheduling
Irrigating on a timer wastes water and energy. Irrigating on measured evapotranspiration and rainfall does not.
- MaxiMet GMX551 solar, wind, T, H, P and rainfall for the ET calculation
- MaxiMet GMX301 solar radiation only, 0 to 1600 W per square metre
- TruMet PW100 optical rainfall, 0 to 200 mm/hr, no bucket to block
Glasshouse and polytunnel climate
Vents, screens and heating all respond to outside conditions, and a control system acting on yesterday’s assumption costs a crop rather than a day.
- MetConnect THP temperature 0.2 degrees C, humidity 1.5 percent RH
- MaxiMet GMX501 wind, T, H, P and solar for vent and screen control
- Blade position sensors non-contact vent and screen actuator feedback
Grain store and crop storage
Stored grain is a season of work sitting in a shed, and it is lost to temperature and moisture rather than to anything dramatic.
- MetConnect THP temperature and humidity, Pt100 input for probes
- MaxiMet GMX300 temperature, humidity and pressure, no wind
- MaxiMet GMX400 adds rainfall for the outside reference
Livestock housing and ventilation
Housed stock lose condition to heat and humidity before anyone sees a problem, and the ventilation control needs to know what is happening outside.
- MetConnect THP temperature 0.2 degrees C, humidity 1.5 percent RH
- WindMaster 3-axis air-flow measurement for ventilation control
- MaxiMet GMX500 outside reference for the shed control system
Slurry, water and fuel tanks
A slurry store overtopping is a pollution incident with a fine attached, and the level is usually checked by looking.
- LevelSlick FEP coated for viscous and particulate liquids
- LevelPro stainless steel, IP66 and IP68, no moving parts
- DD1615 level display local display at the store
Tractor and machinery condition
A machine goes down in the two weeks of the year it is needed, and the wear that stopped it was in the oil months earlier.
- WearDetect oil debris sensing for ferrous wear particles
- LevelLite fuel and hydraulic level, IP68, voltage or current output
- Blade position sensors non-contact implement and actuator position
Rainfall measurement
Rainfall decides travel, application windows and irrigation, and a gauge that blocks with straw dust stops reporting in harvest.
- TruMet PW100 optical, 0 to 200 mm/hr, 5 percent, no moving parts
- MaxiMet GMX603 integrated optical rainfall, 5 percent or better
- MaxiMet GMX551 rainfall alongside wind, T, H, P and solar
Soil and evapotranspiration
Crop water demand is calculated from solar radiation, temperature, humidity and wind, so the weather station is doing agronomy rather than reporting.
- MaxiMet GMX551 all four ET inputs plus rainfall in one housing
- MetConnect THP four-wire Pt100 to IEC 60751 for soil probes
- MaxiMet GMX301 solar radiation, 0 to 1600 W per square metre
Frost risk and protection
Frost protection runs all night on the strength of a temperature reading, and it costs money whether or not the frost arrives.
- MetConnect THP temperature accuracy 0.2 degrees C, Pt100 input
- MaxiMet GMX400 temperature, humidity, pressure and rainfall
- WindSonic M heated, operating to -40 degrees C
Harvest and drying decisions
Harvest moisture and drying cost are decided against the weather, in a window measured in days, on figures that came from somewhere else.
- MaxiMet GMX551 wind, T, H, P, solar and rainfall on the farm
- MetConnect THP humidity accuracy 1.5 percent RH at 25 degrees C
- MaxiMet GMX603 high-accuracy optical rainfall
Buffer zones and boundaries
Buffer zones and neighbour complaints both come down to wind direction at the time of application, recorded rather than remembered.
- MaxiMet GMX200 wind only, 0.5 kg, for a boundary mast
- WindSonic 60 0 to 360 degrees with no dead band
- MetConnect One logs to SDI-12, Modbus or a farm data platform
Worker conditions and heat
Seasonal labour works long days outdoors and in glasshouses, where air temperature understates what the heat is doing to them.
- MaxiMet GMX552 WBGT heat stress with wind, T, H and P, 1.29 kg, IP66
- MaxiMet GMX500 wind, temperature, humidity and pressure
- MetConnect THP reference temperature and humidity
Remote power and telemetry
A field station has no mains and no daily visit, so the power budget decides whether it is still reporting in February.
- MetConnect THP 5 to 30 V DC, less than 70 mA at 12 V DC
- MaxiMet GMX200 0.5 kg, single supply, minimal draw
- MetConnect One SDI-12 v1.3 into an existing farm logger
Calibration and assurance
Farm assurance schemes and application records are audited, and an instrument nobody has verified is a finding waiting to happen.
- UKAS-accredited air velocity calibration traceable certification for anemometers
- Multi-parameter calibration six parameters, equipment from any manufacturer
- Recalibration scheduling intervals, reminders and turnaround
The reference outside and the feedback inside
The outside reference needs wind, rain, temperature, humidity and light, and it needs them from a position that represents the structure rather than a sheltered corner of the site. Wind matters most because vent strategies are constrained by it and because a wrong reading either risks the structure or wastes the venting.
The instrument is on a roof or a mast, outdoors, for years. Anything with a rotating element eventually fouls with dust, pollen and insects, and an anemometer that has seized reports calm, which reads as ideal venting conditions.
Inside, position feedback closes the loop. Vent, screen and damper positions decide whether the control strategy is actually being executed, and that measurement sits in condensing humidity, continuous cycling and, in some houses, spray.
A contacting position sensor in that environment is a consumable. Non-contact inductive sensing measures across a gap to a passive activator, so there is nothing in contact to wear out.
The input to every control decision
Getting the external measurement right is worth more than tuning the control loops, because a good strategy acting on a poor reference produces poor comfort and poor energy use with no obvious cause.
MaxiMet brings wind, temperature, humidity, pressure, solar radiation and rainfall into one unit on one cable, and ultrasonic wind measurement means there is no rotating element to foul with pollen, dust or insects.
One reference, no moving parts
View MaxiMetConfirm the vent actually closed
Control systems generally assume an actuator went where it was commanded. Over a season of thousands of cycles that assumption develops a gap, and the gap is an energy cost that never appears as an alarm.
Blade position sensors measure across a gap to a passive activator with no mechanical contact, sealed to IP67 for temporary immersion (1 m for 30 min). Blade25 measures 25 mm and Blade60 measures 60 mm of linear travel, and Blade360 provides a full 360 degrees of rotary measurement.
Commanded and confirmed are different
Explore position sensorsEnergy and quality are both reviewed
Protected cropping is energy intensive and margin sensitive, and both get reviewed against the season rather than the day. A record of external conditions and actual actuator positions is what makes that review useful instead of anecdotal.
It is also what makes a control change arguable. Changing a venting strategy on the basis of a measured season is a different conversation from changing it on the basis of how the house felt in July.
Labcal is an independent UKAS-accredited laboratory operating to ISO/IEC 17025:2017, calibrating equipment from any manufacturer across temperature, humidity, pressure, air velocity and flow.
What a protected cropping site measures
The outside reference the control system acts on, and the position feedback that confirms it was executed.
Outside reference
MaxiMet
All-in-one weather station, no moving parts
Wind, temperature, humidity, pressure, solar radiation and rainfall from one unit on one cable, sited to represent the structure.
WindSonic
Lightweight 2-axis ultrasonic anemometer
Lightweight ultrasonic wind measurement where the vent and screen strategy is constrained by wind speed and direction.
TruMet PW100
Infrared optical rain gauge
Optical rainfall measurement with nothing to block with pollen, dust or insects, feeding rain-close strategies.
Inside the structure
Blade position sensors
Non-contact inductive position sensing
Non-contact position feedback on vents, screens and dampers, sealed to IP67 for condensing humidity and continuous cycling.
Level sensing
Capacitive liquid level sensors
Continuous level in nutrient, water and dosing tanks with no float, including a FEP-coated variant for aggressive solutions.
MetConnect
Separable sensors for WMO-compliant siting
Separable sensors where the site keeps reference measurement at defined heights or across several structures.
Where protected cropping measurement does the work
Vent and screen control
External reference driving venting, screening and heating, with feedback confirming execution.
Simpler structures
Wind and rain measurement where the structure itself is the thing being protected.
Tight tolerances
Environments where small control errors show up quickly in the crop.
Heating strategy
External demand measurement behind the largest single cost in the operation.
Consistent control
One measurement architecture across structures so that settings mean the same thing everywhere.
Tank and supply
Level measurement across nutrient and water systems feeding the same control platform.
UKAS-accredited calibration for six measurement parameters
Labcal is an independent UKAS-accredited calibration laboratory, Lab 0625, operating to ISO/IEC 17025:2017. It provides calibration across gas and air flow, air velocity, liquid flow, pressure, temperature and humidity.
For a nursery carrying anemometers, thermal probes, pressure instruments, thermometers, temperature and humidity probes and data loggers, one accredited laboratory keeps the whole site on a single traceable schedule.
Gas meters · Mass flow controllers · Dispensing systems
Anemometers · Pitot tubes · Thermal probes
Flow meters and sensors · Process control equipment
Gauges · Transducers · Manometers · Transmitters
Thermometers · Probes · Thermocouples · Data loggers
Hygrometers · Probes · Transmitters
Getting reference and feedback into the control system
Protected cropping control is done by a climate computer or a building management system, and both the external reference and the actuator feedback have to arrive in it rather than alongside it.
Gill supports environmental monitoring, industrial sensing, embedded electronics and systems integration, so growers, control suppliers and structure manufacturers can bring measurement into existing control architecture.
Whether the requirement is Modbus into a climate computer, analogue into an existing input, a serial string into a display, or a configurable sensor embedded into an OEM build, Gill engineers can support integration from specification through commissioning.
Outputs and options
- Modbus RTU : Climate computers and BMS
- 4-20 mA & 0-10 V : Existing analogue inputs
- RS232 & RS485 : Serial links and local displays
- BladeCom : Travel, switch points and output limits set before fitting
What the specification looks like in practice
The reference decides everything downstream
A good control strategy acting on a drifting external measurement produces poor results with no obvious cause.
Nothing to foul with pollen or dust
Ultrasonic wind measurement has no rotating element, which is what fails first on a nursery roof.
Commanded is not the same as achieved
Non-contact position feedback confirms that a vent or screen actually reached the position the system believes it did.
Built for condensing humidity
Blade sensors are sealed to IP67 for temporary immersion (1 m for 30 min), with no mechanical contact between sensor and activator.
One unit for the whole reference
MaxiMet returns wind, temperature, humidity, pressure, solar and rainfall on one cable.
Into the climate computer you run
Modbus, analogue and serial outputs reach existing control platforms.
Questions about glasshouses and polytunnels
Because vents, screens and heating all respond to external conditions, so the reference is the input to nearly every decision the control system takes. If it drifts, the structure runs slightly wrong for a season without alarming.
Confirmation that the actuator reached the commanded position. Control systems generally assume it did, and over thousands of cycles that assumption develops a gap that shows up as energy cost rather than as an alarm.
Blade sensors measure across a gap to a passive activator with no mechanical contact, and are sealed to IP67 for temporary immersion (1 m for 30 min), which suits condensing humidity and continuous cycling.
Blade25 measures 25 mm and Blade60 measures 60 mm of linear travel, both configurable, and Blade360 provides a full 360 degrees of rotary measurement for pivot and screen drives.
Generally yes. The sensors provide Modbus RTU, analogue and serial outputs, and the engineering team can advise on the interface a particular climate computer or BMS expects.
Yes. Labcal is an independent UKAS-accredited calibration laboratory, Lab 0625, operating to ISO/IEC 17025:2017, calibrating equipment from any manufacturer across gas and air flow, air velocity, liquid flow, pressure, temperature and humidity.
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