Monitoring of fridge or freezer to prevent rotten food
icon4 10 3rd, 2011| icon3Comments Off on Monitoring of fridge or freezer to prevent rotten food

Have you ever lost food due to a broken fridge or freezer, or did you ever find a door not shut on your kitchen fridge – after one day ?

Worst, of course, if these things happen in a place you do not regulary stay, such as a weekend cottage or vacation home !

I did this even better …. unplugged the freezer because i needed the power outlet to recharge the car battery .. then forgot to plug back in the freezer …. result, after 5 days …. quite a loss of food ! And a mess to clean up …

Barix Barionet devices can come to the rescue here ! If done right, you can monitor the fridge or freezer for both breakdown as well as open doors etc, without doing any modification or adding sensors to the fridge.

Here’s the secret: get a current sensor such as the RIBXKTF from Functional Devices (costs around $15 if you search online). you will need to install it, best in the electrical cabinet, so the source power for the fridge runs through it. The output of this specific type resembles a “contact closure” (it’s probably a transistor), so you can connect, depending on the type of Barionet you use, up to 4 or even up to 8 of these sensors.

The sensor will not detect the usual “standby” current of a fridge (while the compressor not being active), but it will definitely transmit “on” when the compressor runs.

A fridge/freezer should not be active all the time, there should be alternating periods when the compressor is active and inactive.

A typical graph is here:

Freezer Activity example

Freezer Activity Example

By monitoring the sensor for activity, you can now derive quite some information about your fridge !

– constant “off” tells you the fridge is probably plugged out, switched off or fuse blown, compressor dead etc
– constant “on” tells you the fridge is using a lot of energy, probably because the door is not shut correctly or ice buildup

By calculating the duty cycle (percentage of the fridge being on in a certain period) over time, you can even detect growing inefficiency, when a de-icing makes sense etc – of course, the “nominal” values vary by fridge and average load and need to be determined.

Calculation and alarming can be programmed right into the Barionet or done in a higher level home automation system (such as XTension for the mac – i’m using that myself).

One time rotten food/loss of content can easily cost more than the “Barionet freezer monitor”, if you already use Barionets in your house, just add the sensor …. and of course, this functionality can also be applied to heaters, fans, pumps – about anything which is meant to be on “some times” but not always …

If you want a programming example for the Barionet, contact me – happy to provide that to you as source code.

Home automation that makes sense – with the Barionet, the real-world I/O interface from Barix !

All the best,


Low cost I/O aquisition with Barionet now with time (RTC)
icon4 04 20th, 2009| icon3Comments Off on Low cost I/O aquisition with Barionet now with time (RTC)

This post is in regards to the Barionet – control products, not audio products …

As you know, the Barionet is securing infrastructure, measuring and managing energy, voltages, controlling HVAC systems and supervising power substations since many years.

And, yes, quite some systems also use it for home automation applications ..

One request we hear quite often is that the device should have a RTC (realtime clock), so that it knows the time when it starts up, even if there is no network connection (once it gets the time via NTP from a server, it can maintain it locally, so the RTC is really only needed for having the time after startup with no network).

Good news: the current firmware supports the Dallas Onewire DS1904 RTC button. You can either connect it to the onewire interface, or you can even put it inside the barionet case if you can solder and mount it with velcro or the like.

Here is a link to a wiki article which describes how to do this: Barionet with RTC

What do you get from that ? A low cost universal, network connected I/O controller with RTC, speaking Modbus/TCP, SNMP as well as ASCII protocols, fully programmable …

Please stay tuned for news on the new Barionet 50 model, coming out in the next couple of weeks.