THE CHALLENGEA Cold Chain Breaks Quietly, and Spoilage Shows Up Too Late
Refrigerated transport carries product that is only worth anything if it stays within a temperature band the entire way. When a reefer unit faults, a door is left open, or a box is overloaded, the cargo warms slowly and silently, and the loss is discovered at the receiving dock when the load is rejected. By then the trip data is gone and there is no way to prove who was responsible or where it went wrong. Operators need continuous visibility into the reefer unit itself and into temperature across the load, alerts the moment a zone drifts, and a clean food-safety record that proves the cold chain held.
Sits inside the Telematics and GPS Tracking stack and shares hardware and platform building blocks with Cold Chain Monitoring.
WHAT'S INCLUDED
Inside the Reefer Unit and Across the Load
Reefer Controller Integration
The refrigeration unit is read over CAN for set-point, supply and return air temperature, mode, defrost state, alarms, and run hours. That gives you the unit health alongside a probe reading, so a fault is visible as a fault.
Multi-Zone Temperature Sensing
Calibrated probes placed across the load reveal the real temperature spread rather than a single point near the unit. Multi-temp compartments are each monitored against their own set-point.
Humidity Sensing
For produce and moisture-sensitive cargo, humidity sensors are added, because for many products humidity drives shelf life as much as temperature, and it belongs in the same trip record.
Door-Open Detection
Every door event is logged with time and location and correlated with temperature, so normal stops read as normal and a door left open between stops raises an alert and lands in the record.
Set-Point versus Actual and Excursion Alerts
The gap between commanded set-point and measured temperature is tracked, and excursions raise alerts against per-zone bands with a tolerated duration, evaluated on board so an alert fires even with no signal.
Food-Safety Reporting
The continuous time-stamped record per zone is generated with door events, excursions, and set-point context, exportable in the formats your auditor and customers require as proof of an unbroken cold chain.
WHAT'S MEASURED
The Full Picture, Not One Probe
Reefer monitoring is only useful if it captures both the cargo conditions and what the unit is doing. Sensing on the load is combined with data from the controller so you can tell a warming box from a failing reefer.
From the Unit
Set-point, supply and return air, mode, defrost, alarm codes, and run hours over CAN. The unit tells you when it is fighting the load or has tripped a fault.
From the Load
Calibrated multi-zone temperature and humidity probes show the real spread along the cargo, catching a warm corner the unit return sensor would miss.
From the Doors and Trip
Door events, GPS position, and trip context tie every excursion to where and when it happened, so cause and accountability are clear.
This extends the broader cold chain monitoring capability to the reefer truck specifically, and shares its sensing approach with the vaccine and pharma cold chain solution.
ARCHITECTURE
From the Trailer to the Audit Trail
On the Trailer
An STM32-class controller under FreeRTOS reads the reefer CAN bus and the probe array, evaluates set-point gap and excursion rules, logs door events, and stores the trip record locally so nothing is lost offline.
Transport
A Quectel or SIMCom LTE modem carries telemetry and alerts to the backend over MQTT, with store-and-forward so a dead zone delays but never drops the record.
Backend and Reporting
A time-series store holds the per-zone trace, the platform serves live status and excursion alerts, and the reporting layer generates the food-safety record on demand for auditors and customers.
STANDARDS AND COMPLIANCE
Built for Food-Safety Evidence
HACCP-Aligned Records
Continuous time-stamped temperature logging per zone, with excursions and door events, gives the documented evidence a HACCP plan and food-safety regime expect for transport.
Calibrated Sensors
Probes are calibrated and traceable, so the recorded temperatures hold up under audit and the excursion thresholds mean what they say.
Tamper-Evident Trip Logs
The on-board record is retained independent of connectivity and time-stamped, so the trip history is complete and defensible even if the cellular link dropped during the run.
FAQ
Common Questions
How does the system connect to the refrigeration unit?
The device integrates to the reefer unit over its CAN interface, reading set-point, supply and return air temperature, unit mode, defrost state, alarms, and run hours directly from the controller. That surfaces not only the cargo temperature but what the unit is doing about it, which is the difference between knowing a box is warm and knowing the reefer has actually faulted.
Why multi-zone temperature and humidity?
A single probe near the unit does not represent a full trailer, and multi-temp loads carry different products at different set-points. Calibrated probes are placed across zones to expose the real spread along the load, and humidity sensing is added for produce and other moisture-sensitive cargo where humidity matters as much as temperature for shelf life.
What is set-point versus actual monitoring?
The commanded set-point from the reefer controller is compared against the measured temperature in each zone over time. A persistent gap means the unit cannot hold the load, whether from a fault, a door left open, or an overloaded box. Surfacing the gap, rather than just the raw temperature, is what lets you act before the cargo is compromised.
How does door-open monitoring help?
A door left open is one of the most common causes of a temperature excursion, and on a delivery run doors open constantly. Every door event is logged with time and location and correlated with temperature rise, so a brief opening at a stop reads as normal while a door left open between stops triggers an alert and is captured in the record.
How do excursion alerts work?
You define the allowed band per zone or per product, including how long a deviation is tolerated before it counts. The device evaluates this on board so an excursion alerts in real time with the zone, the temperature, and the location, even across cellular dead zones, and the event is logged for the compliance record regardless of connectivity.
Does this support food-safety compliance?
Yes. A continuous, time-stamped temperature record per zone is produced for the whole trip, with door events, excursions, and set-point context, which is what a food-safety regime and a HACCP plan expect as evidence of an unbroken cold chain. The record exports in the formats your auditor and your customer require, so compliance is generated from the data rather than reconstructed.
Can it run on a mixed fleet of reefer brands?
Yes. CAN integration covers the common reefer unit makes, and where a unit does not expose a usable bus the build falls back to calibrated probes and door sensing so a full record is still captured. Per-brand integration is confirmed during the pilot so the rollout across a mixed fleet is predictable.
Ready to Protect Your Cold Chain?
Share your reefer units, your products, and the compliance you have to satisfy to get the CAN integration, the zone sensing, and the food-safety reporting scoped around your loads.
Schedule a Free Consultation