Multi-Point Temperature Monitoring for Cold Storage Warehouses

Industry: Cold chain logistics / food storage
Products used: Pt100 RTD probes (3-wire), temperature transmitters with RS485 (Modbus RTU) output

The challenge

A refrigerated warehouse operator storing food and pharmaceutical goods had to prove, for customer audits, that every zone of the building stayed within its temperature band — not just the spot next to the evaporator where the single thermostat sat. Battery data loggers had been placed around the building, but they only told the story after the fact: a failed door seal or a drifting refrigeration unit could run for a weekend before anyone downloaded the data, and audit reports meant days of manual file merging.

The solution

We supplied a fixed monitoring network designed around the building's zones:

• Pt100 probes (Class A, 3-wire) at representative points in each zone — near doors, at high level where warm air collects, and beside the evaporators — with probe lengths and mounting matched to each position, including insertion probes for two blast-freezer cells.
• Temperature transmitters converting each point to RS485 (Modbus RTU), daisy-chained on a single bus per zone back to the operator's monitoring system. RS485 was chosen over long analogue runs because the digital signal is unaffected by cable length and electrical noise from the refrigeration compressors.
• A uniform configuration — same probe spec, same transmitter settings, addresses documented per point — so any point can be serviced or replaced without re-engineering the network.

The result

The operator now sees every zone continuously in one system, with alarms raised while a deviation is still a door left ajar rather than a load of compromised product. Audit reporting changed from manual logger downloads to a direct export of the recorded history. The fixed network also paid for itself in calibration discipline: points are checked on a schedule against a reference, instead of loggers being swapped and forgotten.

Why it matters

Cold storage compliance is a measurement problem before it is a refrigeration problem. A modest number of correctly placed, correctly specified Pt100 points on a digital bus gives continuous proof of conditions — and early warning — at a fraction of the cost of the product it protects.

Related products: Platinum Resistance Sensors · Temperature Transmitter Modules