Temperatures in Pizzeria freezers šŸ„¶

General
21

Most of them does NOT.
And even if it would be possible,

  • it would need an extra module,
  • only awailable from the manufacturer,
  • which would take weeks or month to import + pay custom tax + VAT
  • which usually costs $100+
  • and the API is 95% not available.

I know this, because I've tried already.

Also most restaurants are buying freezers ad-hock. So usually each of them is different. (And most of them the cheapest one.)
That would make it an "impossible huge task" not worth it.

Not to mention the "real task":

  • to log all the food + expiration date
  • both when the cook puts it in,
  • or takes it out from the fridge.
1 Like
22

In my country, Poland, I use other devices from this company but they have ones for one sensor via 1-Wire. Set include sensor. Power supply from POE or external 12-24V DC.

Only Ethernet

Nano temperature sensor PoE ~100$ net

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Sensor bus

  • 1-Wire - 2-wire cable

  • Sensor type: DS18B20

  • Measured temperature range: from -55Ā°C to 120Ā°C

Ports

  • LAN: Ethernet 10Mbps, RJ45 port

Communication protocols

  • Embedded web server,

  • Windows and Linux command line programs,

  • HTTP,

  • Modbus TCP,

  • SNMP,

  • Own application, via TCP protocol (shared),

  • MQTT

1 Like
23

Is there are a huge amount of temp sensors for freezers in the market?

Why would you need an extra module?

You could reverse engineer their proprietary ADC using a osiloscope and some measurements taken from a controlled room using another sensor, if they dont provide the way the signal has to be read. It just takes a huge amount of time when you never done it before

I just dont believe you should drill another hole in the freezer to add your own sensor, unless it is possible to keep its thermal insulation intact, while not comprimising their insurance on those freezers

24

check the earlier post - Temperatures in Pizzeria freezers - #10 by PizzaProgram - it sounds like there are a variety of different types of freezer - that are physically separated by some distance - so a simple add-on retrofit would suit better than trying to hack each one.. Flat ribbon cables can be used through most seals without compromising them or needing holes.

2 Likes
25

iā€™d go with lorawan sensors

26

Thank you for your help!

Can you give any specifics here please?

I havenā€™t dig into it, so I do not know enough.

28

If you go for the Sonoff device, how are you going to route the cable into the freezer?

29

If You mean the sensor itself:

  • itā€™s not really my problem, but the restaurant owners' :wink:
  • But seriously: either drilling a hole into the side of it
  • or simply at the door, because there would be only a tiny gap, and most of the door-magnets are flexible.
30

If you suggest that route then make sure the customer knows that the complete sensor head must be inside the freezer.

Assuming it uses the standard waterproof DS18B20 sensor cable then it is 4mm diameter. There will be frost buildup around that. I have one coming today so I will confirm the diameter then.

1 Like
31

The seals really are quite flexible and the doors are probably opened regularly anyway. I very much doubt it would be an issue. Of course, a flat cable would be even better, but I really wouldn't expect the round cable in a DS18B20 to be a problem, especially on a large industrial freezer.

1 Like
32

Thank You very much for the warning!

I guess some silicon glue or at least a chewing gum must be used to seal the hole.
Probably a professional flexible sealing/rubber would be best, so it remains removable, but for start I'll recommend for the restaurant owners a simple hair-rubber-band. :thinking:

33

After reading all the posts, If there was 2 things that are a must on a job like this is a disclaimer to the owner and some good public liability insurance :slight_smile:

2 Likes
34

Sonoff zigbee devices will require a zigbee controller and possible repeaters, as battery devices can not act as network repeaters.

Do the fridges already have a temp display?

Shelly uni and a DS18B20 (-55C) about 25 euros and can be installed in the fridges with existing control gear. No batteries to change.
You could add a cheap esp32 displays Wall mounted Node-RED touch screen device: Request for ideas and volunteers

35

I cant argue against an experienced peer haha

36

Maybe they do, but mostly not. Read back a few posts earlier.

Huhhh... that's a long (162) topic!
Maybe I'll read it once, but I guess restaurant freezers are a bit different than bathrooms.
More important: it is 5 years old! There can be many improvements in 5 years in IoT.

Can you pls. drop a direct link to one of those "cheap esp32 displays" you mean?

Actually "battery" here is a good thing!

  • If there is a power outage, usually switches are not backed up in every room.
  • So reporting of a meltdown would fail.
  • The main POS PC (running my program) has usually an UPS, so a dongle in it would be OK.
  • Forcing the owners to pull cables to every each fridge would cost $500-$1500 (work for an electric worker at late night) I've explained it earlier.
37

I already shared the M5 ones. They are small, well made, not too expensive. They also have battery options as well.

38

Have you tried searching "cheap esp32" on this forum?
or "cheap esp32 display" on the interweb.

No it would not, as an mqtt broker would send a last will topic when the device disconnects due to power outage.

Why would a cable be required these are wifi devices.

39

It is very easy for your PC to detect when a device has stopped sending messages, for example using MQTT last will and testament or simply using a delay node.

40

My Sonoff SNZB-02LD Zigbee temperature monitor with the DS18B20 remote sensor has arrived and works ok with zigbee2MQTT. The cable is thinner than the usual DS18B20 waterproof probe, at 3mm. It would still need a 7mm hole to feed the sensor through if you were using a drilled hole.

41

You've made great progress but I'll chime in. I have a couple of those Acurite sensors in use. The ones I have transmit on 433MHz. I have a small Pi Zero with the RTL-SDR dongle and antenna that picks up the signals. the "rtl_433" software knows how to decode the protocol. It sends me the data via MQTT and into Node Red.