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DS18B20 problem - 127°C - Wersja do druku

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+---- Wątek: DS18B20 problem - 127°C (/showthread.php?tid=687)

Strony: 1 2


DS18B20 problem - 127°C - dudo02 - 02-24-2016

Hi,

I would like to ask you for help.
I have conected LAN CONTROLER as you can see in schematic.
I have got problem, when I switch thermostat contact ON/OFF the value of temperature is jumping UP/DOWN and in finally turn to 127°C.
Doesnt help reboot - value 127°C after reboot still there.
I must disconect power suply, then everithing working(value of temperature is OK), but when I switch thermostat - same prolbem again.


Re: DS18B20 problem - 127°C - pat - 02-24-2016

The problem occurs when thermostat switch on/off or off/on, or in both cases?


Re: DS18B20 problem - 127°C - dudo02 - 02-24-2016

I am not sure.I have to chek it on the site, but I think about both cases.


Re: DS18B20 problem - 127°C - adzik - 02-24-2016

Try use flyback diode parallel to relay!


Re: DS18B20 problem - 127°C - dudo02 - 02-24-2016

Yes I will do that.
I thought that somebody else had same problem...


Re: DS18B20 problem - 127°C - wilkxt - 02-24-2016

You have connected termostat to relay contact on LK?


Re: DS18B20 problem - 127°C - pat - 02-25-2016

Disconnect the relay's power and check the sensor reading. If it works - you need to change the cable - the power supply should not be in the same bundle as the sensor.
How long is the connection between LK and the sensor?


Re: DS18B20 problem - 127°C - dudo02 - 02-26-2016

Willxt-Yes,thermostat is simply mechanical thermostat mounted on the wall and contact is conected in series connection with OUT0 - as you can see in schematic. Also OUT1 and OUT2 connected in the same way with another two thermostats...

pat - DS18B20 is digital senzor so there should not be a problem with interferences. I have similar connection on diferent site where senzors and power for relay goes in CAT5 cable and there is no problem.
And also on another site - sensors are conected separerly on 4wire tephone cable and sometimes I saw same problem...

But here when I switch thermostat ON/OFF one time the temperature first time reach 80C and then go back to normal value.
But if I switch termostat few times in short time then temperature reach 127C...


Re: DS18B20 problem - 127°C - wilkxt - 02-26-2016

you have 12V relay on schematic, what is it for?


Re: DS18B20 problem - 127°C - pat - 02-26-2016

It's not about interference of digital signal but the induction of too high voltage on lines DS18 when switching the relay.