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Introduction to temperature logging

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We use the term Temperature Loggers to refer to small self contained devices that automatically measure and record temperatures. These may be made available immediately, but the prime purpose is to produce a record of temperature over time, usually to confirm compliance with a pre-defined set of limits.
There are currently three different ways to track temperature, RFID (HF), RFID (UHF), and BLE - Bluetooth Low Energy.
Each have their strengths.

RFID HF

This is a good solution for measuring ambient temperature throughout the cold chain. Passive tags are mounted at convenient locations. No battery is required. Reading is by means of a handheld computer.
The range of an HF tag is limited, usually to a few inches, but that is an advantage in this case, where there may be multiple tags in close proximity. A handheld computer is used to read the tag. The application on the handheld computer is set to read, and the user places the handheld computer close to the tag. The current temperature is then recorded.

RFID UHF

These tags include a small battery which powers a low current circuit that is programmed to measure and record a temperature at predefined intervals. Datalogic temperature tag Typically this might be once per hour. Communication with the logging tag is by means of a conventional UHF RFID channel, which means that the batteries are used solely for recording of data - giving a very long working life, which can be several years, dependent on settings.
As with HF tags, these are best read using a mobile handheld computer. Range is greater with UHF, and can be up to several meters, but this can be problematic when several tags are used close together,so range is often deliberately limited.

BLE - Bluetooth Low Energy

These tags are battery powered, and work by taking a temperature at a pre defined cycle, and then transmitting that temperature to a fixed reader. In general, BLE tags are capable of recording presence, temperature and light levels.
The reader will know the identity of the tag, and the current temperature.

Advantages and disadvantages

The HF tags are the simplest solution, they need zero maintenance, and there is no concern about battery life.
The UHF option provides more readings, and can be read at a greater range. Tags are slightly more expensive. Battery life introduces an extra variable. It has another benefit - the data collection is usually performed by an individual who is also performing a routine inspection - and so it provides a confirmation of that all locations were visited.
BLE simplifies the reading process, but is more dependent on setup, and again the tags can be slightly more expensive.

Reporting Temperature

SageData Solutions offers software that can be local, standalone, networked or on the cloud based servers that interact with the handheld computers to set them up, and to collect and analyse data.
Temperatures can be set for high and low limits, and the reporting system will provide a variety of reports, including summary reports, exception reports, or detailed history reports. These include the identity of the individual taking the readings.

Temperature report

Please let us know if you would like to learn more.

If you found this useful, you might also want to review:

an introduction to RFID

RFID read range

BLE for asset tracking

RFID tags