How can I detect a missing DS18B20

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@MosWare
Posts: 10
Joined: Thursday 28 November 2013 18:51
Target OS: Raspberry Pi / ODroid
Domoticz version: v2.4031
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How can I detect a missing DS18B20

Post by @MosWare »

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
Posts: 43
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Re: How can I detect a missing DS18B20

Post by marin849 »

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: 10
Joined: Thursday 28 November 2013 18:51
Target OS: Raspberry Pi / ODroid
Domoticz version: v2.4031
Contact:

Re: How can I detect a missing DS18B20

Post by @MosWare »

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
Posts: 110
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Re: How can I detect a missing DS18B20

Post by alfred_j_kwak »

Make Lua script and monitor lastupdate. There is example on wiki how to monitor garage door.
@MosWare
Posts: 10
Joined: Thursday 28 November 2013 18:51
Target OS: Raspberry Pi / ODroid
Domoticz version: v2.4031
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Re: How can I detect a missing DS18B20

Post by @MosWare »

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: 43
Joined: Tuesday 27 May 2014 10:36
Target OS: Raspberry Pi / ODroid
Domoticz version: 2.4xxx
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Re: How can I detect a missing DS18B20

Post by marin849 »

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 »

My own 'lessons learned' for a disconnected DS18B20: see http://www.domoticz.com/forum/viewtopic ... 948#p54271
Set1 = RPI-Zero+RFXCom433+S0PCM+Shield for BMP180/DS18B20/RS485+DDS238-1ZNs
Set2 = RPI-3A++RFLinkGTW+ESP8266s+PWS_WS7000
Common = KAKUs+3*PVLogger+PWS_TFA_Nexus
plus series of 'satellites' for dedicated interfacing, monitoring & control.
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