Temperature value

Tony · 11 February 2019 08:24

I’m just purchased a RJ45 Encapsulated DS18B20 for my emonTx (running the 3-phase sketch) I plugged it in and it’s generally giving weird high values. The room it is in is warm, about 24, but the sensor is reporting aroud the 210 mark

Anyone have any ideas?

ian · 11 February 2019 08:26

Did you reboot?

Tony · 11 February 2019 08:27

I have and also unplugged and re-plugged a few times.

Robert.Wall · 11 February 2019 12:37

Are you aware that the value transmitted is the temperature × 100? So if you are dividing by 10, that could explain something.

Tony · 11 February 2019 12:44

That’s a good point, but I’m not actually doing anything with it.

Robert.Wall · 11 February 2019 12:52

What value do you read at the Arduino serial monitor?

borpin · 11 February 2019 14:28

That is interesting. My (old) EmonTX transmits such that I x 0.1.

Robert.Wall · 11 February 2019 15:18

Each to their own.

borpin · 11 February 2019 15:59

I am pretty sure that used to be the method. Has the TX script changed such that the temperature sensors are set to a different resolution now? I had a look, but failed to find the relevant section in the Guide.

pb66 · 11 February 2019 19:23

Decimals have never been sent over RFM, whether it’s x10 or x100 for temp or voltage etc, it will never have been anything but an integer, to be scaled in emonhub or emoncms depending on your setup.

borpin · 11 February 2019 19:27

Mmm, I though so. How then could they be appearing in the inputs on the first post? MQTT?

pb66 · 11 February 2019 19:29

Seems the scales have been incorrectly set in emonhub.conf

github.com

openenergymonitor/emonhub/blob/v2.1.2/conf/emonhub.conf#L140

    
      
                 names = power1, power2, power3, power4, vrms, temp1, temp2, temp3, temp4, temp5, temp6, pulse
                 datacode = h
                 scales = 1,1,1,1,0.01,0.1,0.1, 0.1,0.1,0.1,0.1,1
                 units =W,W,W,W,V,C,C,C,C,C,C,p
          
          
[[11]]
              nodename = 3phase
              [[[rx]]]
                 names = powerL1, powerL2, powerL3, power4, Vrms, temp1, temp2, temp3, temp4, temp5, temp6, pulse
                 datacodes = h,h,h,h,h,h,h,h,h,h,h,L
                 scales = 1,1,1,1,0.01,0.1,0.1,0.1,0.1,0.1,0.1,1
                 units =W,W,W,W,V,C,C,C,C,C,C,p
                 
           [[12]]
              nodename = 3phase2
              [[[rx]]]
                 names = powerL1, powerL2, powerL3, power4, Vrms, temp1, temp2, temp3, temp4, temp5, temp6, pulse
                 datacodes = h,h,h,h,h,h,h,h,h,h,h,L
                 scales = 1,1,1,1,0.01,0.1,0.1,0.1,0.1,0.1,0.1,1
                 units =W,W,W,W,V,C,C,C,C,C,C,p

The raw (x100) temp reading are being divided by 10 in emonhub so they land in emoncms x10 (all 4 templates are apparently wrong)

The sketch source seems correct

github.com

openenergymonitor/emontx-3phase/blob/V1.4.0/src/src.ino#L46

    
      
          
          
emonhub.conf node decoder settings for this sketch:
          
          
[[11]]
              nodename = emonTx_three_phase
              firmware = three_phase
              hardware = emonTx V3.2/V3.4/Shield
          [[[rx]]]
              names = power1, power2, power3, power4, Vrms, temp1, temp2, temp3, temp4, temp5, temp6, pulsecount
              datacodes = h, h, h, h, h, h, h, h, h, h, h, L
              scales = 1,1,1,1,0.01,0.01,0.01,0.01,0.01,0.01,0.01,1
              units =W,W,W,W,V,C,C,C,C,C,C,p
          
          
IMPORTANT NOTE:
          When used in the 3-wire configuration with one line conductor being treated as the 'neutral', the
          individual powers recorded for the other two line conductors are meaningless, only the TOTAL power
          of the line conductors has a physical meaning. Therefore, 'power1' is the COMBINED power of inputs 1 & 2
          and all the values for input 2 alone are set to zero.
          Note also: Only one temperature sensor may be connected. All remaining temperatures will read "300.00"
          
          
For serial input, emonHub requires "datacode = 0" in place of "datacodes = ...." as above.

[edit - PR for corrections done]

Robert.Wall · 11 February 2019 21:49

The “temperature × 100” derives from MartinR’s original PLL sketch dated December, 2012.

borpin · 11 February 2019 21:55

Just so I am clear (as I run a really old EmonHub that is in ‘ain’t broke don’t fix’ mode), is there now no need to do any multiplying at the EmonCMS end?

pb66 · 11 February 2019 22:47

Me too!

The old original emonhub only has datacodes, scaling wasn’t implemented. The “emonpi” variant of emonhub on the emonSD does the scaling before sending/publishing so then no additional scaling is required in emoncms.

As a side note, the scaling, as it is in the emonpi variant has been used for clibration and IMO now I have clocked up a fair bit of time using Modbus, I believe a “scaling factor” is a better method.