DS18B20 - Naming/numbering rules

[Craig Curtin]

Guys,

Using Tasmota (11) on Sonoff TH16 - i have 7 DS18B20 attached and working well.

In Node red i am grabbing the DS18B20 number as sent over in the Sensor output and all seems well.

I was wondering what happens if a sensor dies/stops reporting so instead of 7 sensors i now have (say 5) what happens with the naming/numbering of the remaining sensors after a reboot.

I assume that the unique identifier that is transmitted with each DS18B20 is a partial serial number from the chip - or is that a calculated number ? i.e. what can i rely on to be unique on an ongoing basis to ensure i have the right temperature sensor each time ?

Craig

[Philip Knowles]

The numbers in the UI renumber - so if you lost number 3 - 1 and 2 would stay the same and the rest would 'shuffle' down. The ID is the laser etched ID within the DS18B20 so remains constant and is the value that should be used from the JSON. That causes problems with parsing for some softwares.

Ideally there should be a SetOption to choose internal (Tasmota) ID or DS18B20 ID in the JSON.

I run openHAB and node-red (on a Pi to handle some remote devices RS232 based devices). I have 2 devices with multiple DS18B20s. I had random issues about 3 years ago (wiring it turns out) so I parse the outputs in node-red and 're-transmit' using the DS18B20 ID. It also warns if a device disappears (unused since I fixed the wiring issue).

Regards

Phil K

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From: sonof...@googlegroups.com <sonof...@googlegroups.com> on behalf of Craig Curtin <craig....@gmail.com>
Sent: Monday, May 2, 2022 1:01:05 AM
To: TasmotaUsers <sonof...@googlegroups.com>
Subject: DS18B20 - Naming/numbering rules

 

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[Craig Curtin]

Excellent - thanks for the informative reply - i will continue to use NR to expose the Etched in number then and will use that for all of my decisions

regards

Craig