Full-Spectrum Photosynthetically Active Radiation Sensor

Low driftComponent grade

AC 220 VTypical supply

RS485Uplink

IP67Enclosure

Product Overview and Engineering Role

The SimtoLink full-spectrum PAR sensor is for environmental sensing on an IoT site. The measurement and communications path uses a 24-bit Σ-Δ ADC, and stays predictable across wide temperature, supply voltage, and EMI. Full-spectrum PAR needs a stated integral from 400～700 nm and a quantum-flux conversion under LED and sunlight, and the optical window has to be cleaned on a schedule so biofilm does not pull the reading down. It is built to be serviced in the field: pluggable terminals, a watchdog and redundant checks on the critical chips, and signed firmware that can roll back, so a batch can ship and then be maintained from a distance.

The usual outputs are isolated RS485/Modbus and 4–20 mA, with an Ethernet order code if you need it, so the sensor can sit on an existing SCADA, energy-management, or IoT platform. SimtoLink supplies a southbound point-table template and northbound MQTT/HTTP push examples to shorten joint commissioning. Volume jobs can include enclosure silkscreen, harness length, protocol mapping, and a calibration certificate.

Reliability and Site Conditions

On electrical safety and EMC, this sensor has cleared the relevant CCC items. The ports include surge and reverse-polarity protection. A reinforced ground and a split layout keep ground loops and common-mode noise down. Outdoor or coastal sites can take a higher ingress rating and a corrosion-resistant coating.

Parameters can be imported in bulk. Threshold rules, and event video or waveform capture, depend on the model. Configuration and firmware move by OTA. On site, run three checks: power-on self-test, time sync on the link, and a spot check of samples. Where the sensor is used for metering or for safety, SimtoLink can help with a third-party metrology submission and the type-test file.

Key Hardware Parameters

The table is the typical configuration of this PAR sensor, for selection and for bid clauses. A wider range, redundant power, or an intrinsically safe variant is available from SimtoLink with the Hardware Specification and the Installation and Commissioning Guide. Order codes in the family can differ slightly; the nameplate and the documents shipped with the sensor govern.

Parameter	Specification	Notes
Sensing principle	Multi-band photoelectric (full-spectrum PAR)	Photosynthetically active radiation, 400～700 nm
Range	0～3000 μmol·m⁻²·s⁻¹ (typical)	Custom range available
Resolution	1 μmol·m⁻²·s⁻¹ (typical)	Digital output
Repeatability	±2 % of reading (typical)	At constant temperature
Yearly stability	±2 %/year (typical)	Depends on window soiling and calibration
Power	AC 220 V / DC 12～24 V	By order code
Communications	RS485/Modbus + 4～20 mA	Isolation by model
Start-up	<5 s (typical)	Ready on power-up
Operating temperature	-40～70 ℃ (electronics bay, typical)	Probe IP67
Hazardous area	Not explosion-proof (typical)	Customized per project

Typical Deployments

Three layouts that come up when you put this sensor on an IoT job and look at payback:

Plant and energy sites

On a production line or in a power room, the sensor talks to MES or EMS and sends process or energy readings up from the edge.

Municipal and utility sites

Scattered points and outdoor cabinets, with a wide temperature range and lightning protection, for long runs and low-latency watch on water, gas, and street lighting.

Campuses and buildings

The PAR sensor feeds a campus energy system or a building controller for sub-metering, fault alarms, and policy interlock, so fewer rounds of manual reads and walk-downs.

Installation, Grounding, and Maintenance

Before power-up, confirm the supply range and polarity. Check bus voltage and breaker rating with a meter when you need to.
Use shielded twisted pair for the bus, ground the shield at one end, and do not bundle it with high-power cables for a long run.
For the first connection, prove two-way reads and writes and a threshold trip against the platform in the lab, then move the sensor to site.
Outdoors, give water a way out and leave the enclosure able to breathe. Inspect the seal on a schedule. Lightning-ground resistance has to meet the local code.
In service, sample the readings and archive the logs every 6 months.

Ordering, Documentation, and Support

SimtoLink supplies the hardware specification, dimension drawings, a wiring table, and a sample project for this sensor. Volume orders can include a sample review and a factory inspection. Warranty and calibration follow the contract and the documents shipped with the unit.

Where It Is Used

Photosynthetically active radiation drives crop models and greenhouse climate control. The full-spectrum version is the better fit when you are judging a new light source. The cases below turn on mounting angle, the daily integral, and the handoff into irrigation.

Glasshouse light recipes

Shade screens, HPS lamps, and LED fill light close the loop with CO₂ enrichment, temperature and humidity, and irrigation. Daily light integral (DLI) drives flowering and fruit sizing. A heater on the optical window keeps condensation off so the reading stays stable.

Under agrivoltaic modules

Photosynthetic photon flux density in the shaded band under the modules, used to screen shade-tolerant varieties and combinations of rack height and module tilt. The record supports a land-sharing case and crop-insurance loss assessment.

Flux towers at research stations

PAR is sampled together above the canopy and at several points in the stand, for carbon-flux partitioning, checks of radiative-transfer remote sensing, and phenology-model calibration. The time base stays locked to the eddy-covariance clock.

Multi-tier vertical farms

Each tier closes its own PAR loop on LED current and duty cycle, to cut tip burn and uneven low light on the bottom tier. Tied to a circuit meter, it improves photosynthetic photon efficacy (PPE) and yield per kilowatt-hour.