Reefer controllers, cold room sensors and cellular shipment loggers publish temperature, door and location data as it happens. Dispatch, quality and your customers see the same live readings — and an excursion triggers an alert in transit, not a rejected load at the dock.
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PUBLISH cc/reefers/trl-5521/telemetry
{"ts":"2026-10-22T07:41:10Z","setpoint_c":5.0,"supply_c":4.6,"return_c":5.3,"box_c":4.9,"door":"closed","lat":51.37,"lon":6.17}QoS 1 · TLS 8883 · PUBACK
Many shipments still travel with USB data loggers that are read only on arrival — by then a load of vaccines or fresh produce is already lost. Reefer telematics, warehouse cold rooms and shipment trackers each live in their own portal, so shipper, carrier and 3PL argue over whose data is right. A reefer that fails at night or a cold room door left open is noticed in the morning.
Reefer controllers report supply, return and box temperature and setpoint; cold rooms use probes and door contacts; shipments carry cellular loggers with temperature, light and GPS.
Telematics units and gateways publish to topics per trailer, room or shipment over TLS. Devices buffer readings in dead zones and send them with QoS 1 when coverage returns.
Your TMS, WMS and quality system subscribe to the topics they need; a customer portal gets read-only access to its own shipments.
Threshold rules notify the driver, dispatcher or warehouse team when a temperature leaves its range or a door stays open. Where the reefer supports it, setpoint changes go back on a command topic.
Small packets for cellular, keep-alive tuned to the network, persistent sessions so trailers pick up queued commands after a tunnel or a border crossing, and Last Will to flag a unit that drops off.
Per-device credentials and topic ACLs let carriers, 3PLs and customers see exactly their own trailers, rooms or shipments — and nothing else. TLS on every connection.
Threshold rules on temperature and door state notify the right people straight from ConnectMQ, while the live dashboard and topic monitor show every reading as it arrives.
Every reading arrives timestamped on a well-defined topic, so your quality system or WMS can store the temperature history it needs for release decisions and claims.
cc/reefers/trl-5521/telemetry
cc/reefers/trl-5521/events
cc/reefers/trl-5521/setpoint/set
cc/rooms/dallas/cr-03/climate
cc/shipments/shp-88231/logger-17/readingsMQTT moves each temperature reading from the reefer, cold room or logger to every system that needs it — TMS, WMS, quality and customer portals — in real time over cellular. Small packets and persistent sessions suit moving assets with patchy coverage, and threshold rules raise an alert as soon as a value leaves its range.
MQTT can carry the data in a monitoring solution you qualify: loggers and telematics publish, and your quality system stores the records and handles deviations. ConnectMQ provides the broker, TLS, access control and alerts; it is not itself the validated temperature record.
Many reefer telematics units and IoT gateways publish MQTT directly; others expose data through the vendor’s cloud API, which a small bridge can publish to ConnectMQ. Either way, use one topic per trailer and a separate command topic for setpoints.
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