How can I detect a missing DS18B20

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@MosWare
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How can I detect a missing DS18B20

Post by @MosWare » Monday 11 January 2016 13:34

Hi,

I connectet some DS18B20 temperature sensors to the Raspi GPIO port and it´s working fine.
But when I disconnect the dataline, it`s not recognized by Domoticz.

Is there a possibility that Domoticz responds to a missing sensor?

Best Regards
@MosWare

marin849
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Re: How can I detect a missing DS18B20

Post by marin849 » Monday 11 January 2016 19:16

When a sensor hasn't been updated in X minutes it will we marked red in Domoticz. You can change the timeout in settings-other-timout for sensor.

@MosWare
Posts: 12
Joined: Thursday 28 November 2013 19:51
Target OS: Raspberry Pi
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Re: How can I detect a missing DS18B20

Post by @MosWare » Wednesday 13 January 2016 8:18

Thank you for your answer.

It is right, that the value is marked red, but the value didn´t change.

How can I set a switch (for example an alarm lamp) while
Sensor communication is lost?

Best regards
@MosWare

alfred_j_kwak
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Re: How can I detect a missing DS18B20

Post by alfred_j_kwak » Wednesday 13 January 2016 11:27

Make Lua script and monitor lastupdate. There is example on wiki how to monitor garage door.

@MosWare
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Joined: Thursday 28 November 2013 19:51
Target OS: Raspberry Pi
Domoticz version: v2.4031
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Re: How can I detect a missing DS18B20

Post by @MosWare » Wednesday 13 January 2016 22:30

Hmm, but on loss of communication freezes the value.
There is no difference between a freeze value an a real stable value.

I think this should be realized by Domoticz, without the need of writing a LUA script for this elementary function.
When communication lost, Domoticz could set the value to -1000 °C. So it would be very easy to implement for anyone.

Or, is there a way to request a sensor time out?

Best regards
@MosWare

marin849
Posts: 65
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Re: How can I detect a missing DS18B20

Post by marin849 » Monday 25 January 2016 0:32

There is no need to use false values to detect a missing sensor. That would also mess upp the temperature logs.
The lastupdate value tells you when the sensor was last updated.
So you can make a LUA-script that reacts when a sensor has not been updated for 15 minutes for example.

Also, Domoticz colors sensors in read when they have not been updated within a time that you can select in settings.

Toulon7559
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Re: How can I detect a missing DS18B20

Post by Toulon7559 » Monday 25 January 2016 13:35

My own 'lessons learned' for a disconnected DS18B20: see http://www.domoticz.com/forum/viewtopic ... 948#p54271
Set1 = RPI-B+RFXCom433+S0PCM+Linksprite-shield for BMP180/DS18B20/RS485+DDS238ZN1
Set2 = RPI-3+RFLinkGTW+ESP8266s+PWS_WS7000
Common = 2*PVLogger+PWS_TFA_Nexus+KAKUs
=> Energy & Data Management based on Time and on PV&Consumption&Meteo

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