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Hello Hrant, I wonder if you could try running the emonpi updater from the Admin menu in emoncms, it will re-upload the firmware and ensure all the latest updates are on there. Just tested a couple of emonpi's here and they all seem to be sending the temperature data ok. It may be something to do with the way the firmware detects the sensor, it would be useful to know if that fixes it.

Hi TrystanLea,

Thanks for answering, I will most certainly test that tonight when I get back home, in the meantime let me provide further details of some tests I did in hopes that it sheds more light to the issue.

Test 1
After the above tests, I removed the SWE2b board and connected the "RJ45 Encapsulated DS18B20 temperature sensor" directly to EmonPi, and right away the T1 readings changed from 25.5C to 23C, indicating that the device was back to reading data properly (23C is more reflective of the room temperature)

Test 2
Removed the Sensor, (no Temperature sensors attached) and the temperature reading jumped back to 25.5C

Test 3
Remove all other sensors from SWE2b board, and just connect one RJ45 to EmonPi, and connect the other to "RJ45 Encapsulated DS18B20 temperature sensor" from Test 1
Temperature reading briefly showed 45C or something high then showed 23C (I can see that it is now reading 23.1C, hence I'm assuming that it is working ok with that sensor)

Next tests that I will perform, in addition to updating the firmware.
Start testing every connection points of SWE2b board with a Temp sensor one at a time, in hopes of identifying a bad connection point or a sensor (I have few sensors I can test with)

In any case reading 25.5C with no sensors connected is probably an indication that a firmware / board issue exists.

Thanks
Hrant

Hi TrystanLea,

I did the update and tested again, unfortunately nothing changed.

After the update with the RJ45 Temperature sensor plugged in, I get a good reading, when I unplug it, it jumps straight back to 25.5

Plug back and it's back to proper reading.

So definitely something is wrong somewhere.

Even if I reboot with no sensor plugged in, I'm getting a reading of 25.5

Now with the board attached.

No matter what combination I try, whichever type of sensor (I have both kinds) on any of the 6 end points, I only see Temp 1 reading and stuck at 25.5, unless I plug in the RJ45 sensor to the board, then I see Temp 1 reading,

still nothhing from the others.

Is this board just plug and play or there needs to be some settings applied somewhere?

Looking at the pins of the board and testing with multi-meter I can see that all the nodes are connected in parallel, ie, all teh grounds together, all the +5V together and all the 1-Wires together (sadly I cannot confirm by looking at the schematic as the link for Download PCB CAD Files (FreePCB format + Gerbers  http://files.openenergymonitor.org/CAD_files/SWE2bv1.0.REVISED.zip is broken)

If they are all connected to each other in parallel, how does emonpi know how to detect one or multiple?

Thanks for looking into the issue.

Hrant

Hi TrystanLea

Any suggestion on how to proceed?

Thanks

Hrant

Hrant,

If they are all connected to each other in parallel, how does emonpi know how to detect one or multiple?

This is the clever part of the 1-Wire technology.  All sensors connect to the same data wire.  Each sensor has a unique serial number in read-only memory, and when the software starts up it asks the sensors to identify themselves.

Hello hrant, Il try and get back to you later today after doing a bit more testing on this.

Hello hrant, could you try a full power down including taking the power out, then before powering up connect all the temperature sensors. I cant quite work out from the above if you did this, a soft reboot wont reset the emonpi-shield it just resets the raspberrypi.

When you power up the emonpi does the LCD on the emonpi say that there are multiple DS18B20 sensors connected? it says how many are connected after the initial "emonPi v1.10", "OpenEnergyMon" and AC wave screen.

Hi TrystanLea

Awesome, that was it, powering it down, unplugging the power then powering back on showed 5 DS18B20 sensors and now all of those sensors are showing values.

Although all sensors are next to each other (for this test), and one would expect the same reading on all of them

I see quite a bit of variation.

The senors read the followng.

25.1

25.6

25.5

25.8

26.2

And my room thermostat temperature reading is 24.5 Celsius

Is this normal?

ON another note, when I remove the RJ45 sensor, I still get 25.5 values for it, I have no idea where this figure is coming from, not that it bothers me as I don't plan to remove it, however it suggest a problem in firmware / electronics.

Steve, many thanks for the explanation.

TrystanLea, you saved the day, many thanks

Hrant