Announcement

Collapse
No announcement yet.

One wire DS18b20 value spike -127.00

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    One wire DS18b20 value spike -127.00

    As the topic title says.
    I have installed 2 x 18b20 one wire sensors (on another location and new board mega2560) , used a pull op resistor as described.
    Both sensors work correct but once in a while i get a reading for a short second that says -127.00 degrees.

    I noticed this at my own home with 12 sensors also, thought it was caused because of the long daisychained link or something.
    I am logging at home with a simple logger for graphs but i noticed this that it ruined my graphs.
    Normally temp hoovers around 20 deg, the graph is wit a 20 degrees scale, but when the -127 comes by, the whole graph is not readable anymore and tiny.

    What can be the cause of this, i am probably not the only one experiencing this ?

    Thanks

    #2
    I've seen that a few times with DS18B20 devices, I don't know if there is a cure I think it is when it gets a bad packet and tries to convert it so it gives you the lowest value of a signed 8 bit number (-127). I don't use the plugin but I use a Spark Core which gives the same occasional result, as such in a HS script I do;

    Code:
     Select Case convert.todouble(tempData.result)
                Case -10 To 50 : hs.setdevicevaluebyref(448, convert.todouble(tempData.result), True)
            End Select

    Comment


      #3
      I believe this is caused sometimes with connection problems. I think there is a catch in the plugin for this to try and reduce the problem so If you are seeing it I would try checking the connections. Are the cable runs long. Have you tried changing the resistor value? Have a Google as there are some good pages out there about one wire problems. I will also have a look at the code but I think we have been here before.

      Greig.

      Sent from my SM-G925F using Tapatalk
      Zwave = Z-Stick, 3xHSM100� 7xACT ZDM230, 1xEverspring SM103, 2xACT HomePro ZRP210.
      X10 = CM12U, 2xAM12, 1xAW10, 1 x TM13U, 1xMS13, 2xHR10, 2xSS13
      Other Hardware = ADI Ocelot + secu16, Global Cache GC100, RFXtrx433, 3 x Foscams.
      Plugings = RFXcom, ActiveBackup, Applied Digital Ocelot, BLDeviceMatrix, BLGarbage, BLLAN, Current Cost, Global Cache GC100,HSTouch Android, HSTouch Server, HSTouch Server Unlimited, NetCAM, PowerTrigger, SageWebcamXP, SqueezeBox, X10 CM11A/CM12U.
      Scripts =
      Various

      Comment


        #4
        Thanks for the replies guys,
        The cable is from the first sensor that is 10 CM max from the arduino away, the longest part is 12 Meter.(sensor outside)
        2 sensors are on the cable.
        Just a moment ago i saw it again for a second and made a screenshot.


        I haven't tried another resistor yet, but this location is 200Km away from my home so can't change it right now haha.

        Comment


          #5
          Vincenttor

          If your server cabinet is 48c then I'd expect smoke :-)

          I have a DS18020B approx 30cm from the arduino and another an additional 1m away, so 2 devices 1.3m in total from the device.

          I have done this on 2 megas...I graph with Jon00's code and I've never seen this type of spike. I am using 4 core "Alarm wire" with a 4k7 at the arduino.

          I'm not seeing this type of issue....I really dont have any experience except for "default", the configuration I have is the default basic config and that seems to work....its that simple that the bare wires are tinned and pushed into the connectors of the arduino.

          Maybe you should do something similar at your home location on a workbench and let it test for a while to see what happens ?

          Best of luck

          Pete
          HS 2.2.0.11

          Comment


            #6
            Well how about that, its happened twice, never seen this before in the logs

            Feb-22 8:26:45 AM Arduino Plugin Error = Exception in RecievedData Value > -100 And Value < 150 : Conversion from string "4023086254050000221, value Error" to type 'Long' is not valid.

            This worked for me as it was filtered out nicely :-) Didnt break my graphs

            Pete
            HS 2.2.0.11

            Comment


              #7
              Originally posted by Vincenttor View Post
              Thanks for the replies guys,
              The cable is from the first sensor that is 10 CM max from the arduino away, the longest part is 12 Meter.(sensor outside)
              2 sensors are on the cable.
              Just a moment ago i saw it again for a second and made a screenshot.


              I haven't tried another resistor yet, but this location is 200Km away from my home so can't change it right now haha.
              Which version of the Arduino plug-in are you using? I think Greig put the traps in much later than the current release version. The release version is 1.0.0.36, the beta is 1.0.0.103. The beta is safe as far as I am concerned - I've been running it on 4 boards since it was released without issue. Each of the boards has a OneWire device and they are all graphed.

              Comment


                #8
                Originally posted by Vincenttor View Post
                Thanks for the replies guys,
                The cable is from the first sensor that is 10 CM max from the arduino away, the longest part is 12 Meter.(sensor outside)
                2 sensors are on the cable.
                Just a moment ago i saw it again for a second and made a screenshot.


                I haven't tried another resistor yet, but this location is 200Km away from my home so can't change it right now haha.
                Originally posted by petez69 View Post
                Vincenttor

                If your server cabinet is 48c then I'd expect smoke :-)

                ...

                Pete
                That is a bit warm. My server closet rarely sees 29c.

                Comment


                  #9
                  Thanks for the replies, about the temp in the cabinet.
                  Yes thats way to high, my dad mounted a heating element with a external thermostat.
                  Old one with a i think it's called bi metal ? and a knob to set the temp.
                  But he turned the knob and it is going crazy, the element stays on.
                  I can control it by the arduino but can only turn it on at the moment, wanted it to have a backup when temp dropped to 0 deg it would turn on without the arduino.

                  This in mind that if something was broken, the arduino for example the heating element would still function.
                  It does not go further then 50 degrees in the isolated cabinet but still this is not how it was planned.
                  Problem is that this location is 200Km away from where i live and can't do much about it now, we have send someone in to pull the power cord and next time i arrive there i will change the thermostat that this does not happen anymore.

                  The version i am using for the arduino is the stable one, haven't got the courage to install the beta version on this location since its not easy to reach for me.
                  But maybe i will upload the beta version then next time i arrive

                  The wires i use is a simple cat 5e pure copper no CCA or CCS not shielded or anything.
                  At my parents home i have seen these figures also from time to time but the cable in there house is much longer.
                  I think it is about 65 meters going to every room and back.

                  Comment

                  Working...
                  X