Deep freezer

The conservation of goods (food, medicine, materials) is very important. Usually laboratories and industries have deep freezers for conservation. The variation of the temperature may affect the quality of a good. For this reason is important keep under control the temperatures. You can setup a control application based on AirQ Networks products.

You can control:

  • temperature of a cold storage room;
  • temperature of a deep freezer (-80°C);
  • temperature of isothermal truck;

This is just an example, but it’s possible to build more complex systems, for instance the system can detect if the door of a deep freezer has been left open for too time etc.

The application must detect temperatures, calculate the archive of the data collected, and alarms if any temperature is outside a certain threshold.

Suppose you have:

  1. a cold storage room;
  2. four -80°C deep freezers without a plug for a probe and an alarm contact;
  3. an isothermic truck.

The system will calculate HACCP register automatically and activates following alarms:

  1. Send SMS (text message) to mobile number if cold storage room temperature is out of interval [-25°C -15°C];
  2. Send SMS (text message) to mobile number if one of the deep freezers alarm contact is on (suppose you use a normally open contact);
  3. Send Email when isothermic truck enter/leave the factory.
Cold storage

Deep freezer

Deep freezer

Cold storage room

Isothermic truck

Isothermic truck


Required stuff

  • N° 1 AirQ 101 sensor (for point 1);
  • N° 1 AirQ 121 datalogger sensor (for point 3);
  • N° 1 control board with at least 4 inputs, like AirQ 305 or AirQ 325 (for point 2);
  • N° 1 ColdNET control unit;
  • N° 1 12V power adapter.

Note the use of the datalogger for the isothermic truck: the AirQ 121 sensor collects data when it’s out of control unit detection range (the truck is out for delivery); the sensor downloads all data collected when it’s in control unit detection range (the truck is returned to the base).

Step by step instructions

Let’s start with simple tasks: install the sensors AirQ 101 and AirQ 121. Being battery powered sensors, they can be placed where needed. As rule of thumb, we suggest to try different places before to decide final position. An important trick is to avoid placing a sensor too close to some air vents or sources of heat.
Next step is to link alarm contacts of the deep freezers with the board AirQ 305. You have to insert the power adapter into the plug and link it to the board. Since you have 4 alarm contacts, you have to link each of them with one input of the board. It is preferable to make the connection on normally open contact of the freezers.
Finally, the control unit must be installed close to a network outlet using an UTP cable and powered up using a +12V power adapter.

Deep freezer schema

A schema for cold chain monitoring

Software setup

In order to configure software, you have to access to the web server ColdNET embedded in the control unit. You can access to ColdNET using a browser, typing in the address bar:

Control unit IP address is provided by DHCP. To retrieve the address you have to use HomeNET Finder.

After login, the main page is the devices status summary. In this view you can see a box for each device that you have paired to the control unit.

deep freezer main view

Devices status summary for a cold chain monitoring

As you can see from the previous image, you can customize device names, the names of the inputs and the names of the relays of the control board. The input icons of the control board will light if the deep freezers have alarms. The box of the isothermic truck changes its temperature value every time that the datalogger is in the radio range of the control unit. The Sensor box of the cold storage room/freezer changes its temperature value every 4 minutes if the temperature grows or decreases of 0.5°C, otherwise every 8 minutes if the temperature is stable.

Dashboard setup

You could prefer to use a graphic panel that focuses only what you need: for instance you could show:

  • The status of the four inputs of the control board;
  • The temperature of the cold storage room;
  • The trend of the temperatures of the isothermic truck.

So you can use the dashboard. Following the guide of the dashboard, you can obtain a panel like in following picture:

dashboard of the cold chain

A dashboard example for cold chain monitoring

Define system logic

To alarm definition, you need to set more complex behaviors by using rules.

Send SMS (text message) to mobile number if cold storage room temperature is out of interval [-25°C -15°C]

From the dashboard, click on rule icon for the freezer sensor to access managing rules page grouped by the freezer sensor.

In the add new rule box, you have to define a rule name, some conditions and an action:

  • Conditions: temperature is higher than -15; temperature is lower than -25;
  • Action: send SMS to mobile number.
rule for the refrigerator

A rule that controls the temperature of the cold storage room

Please note the text body of the SMS. The string <V>cold storage room (</V> has been added after clicking on the dropdown menu on the left in the sendSMS box. When the conditions of the rule are verified, the software replace the string <V>…</V> with the temperature detected by the sensor and then sends the SMS using the Igloo web service.

Send an SMS to mobile number if one of the deep freezer alarm contact is on

For each of the four input of the control board, you have to define this rule:

  • Condition: if alarm contact is on;
  • Action: send SMS to mobile number.
A rule for a deep freezer alarm

If an input of the control board has boolean value True, the control unit sends an SMS

Send an Email when isothermic truck enter/leave the factory

If you want to be notified every time the truck leaves or returns in factory, you need to set two rules:
rule 1:

  • Condition: if truck leaves the factory;
  • Action: send E-Mail;

rule 2:

  • Condition: if truck returns to factory;
  • Action: send E-Mail;

You can setup the conditions by checking if sensor is in radio range of the control unit, using the parameter “linked”.

a rule for truck outgoing

A rule for the truck outgoing that uses the status of the signal of the datalogger.

a rule for truck ingoing

A rule that detects if the truck is returning


Note the definition of DURATION. The actions in the two rules have the duration value 10. This means that the control unit have to send the Email within 10 seconds. After the 10 seconds the action is disabled and then it will re-enabled only after the condition state changes. All this ensures that the message will be sent only one time in outgoing or in return.

Observe the data

ColdNET provides more tools to observe the collected data. You can see collected data in tables or in graphs. For instance, you can:

  • Observe the trend of the temperatures detected by the datalogger during the deliveries of the isothermic truck;
  • Observe the old statuses of the alarm contacts of the deep freezers.
trend of temperatures of the datalogger

Trend of temperatures of the datalogger, represented in a graph

history of deep freezers

a tabular history of the deep freezers