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emonTx V3 Temperature reading 300

I have a new emontX V3 which I have just installed along with emonBase.
The power/voltage is all working fine but the temperature sensor “1 x RJ45 Encapsulated DS18B20” is not working. I’m seeing a value of 300.

Any thoughts appreciated.

300 is an error code for an absent sensor. Have you reset/restarted the emonTx since plugging in the temp sensor? If you have and it still isn’t seen, then most likely you have a bad connection, check the rj45 connection is tight and that all the gold pins look like they are fully home in the rj45 plug.

Thanks for the suggestion. A restart didn’t work so I’ll go find my RJ45 crimp tool :slight_smile:

As an aside I;m seeing “unreliable content” in the logs, is this anything to worry about?

2018-02-15 15:04:24,740 DEBUG    RFM2Pi     Discarding RX frame 'unreliable content'? 19 22 149 134 223 101 114 53 178 90 186 142 150 106 144 249 54 129 30 128 45 (-104)
2018-02-15 15:04:26,783 DEBUG    RFM2Pi     Discarding RX frame 'unreliable content'? 15 91 155 7 121 19 93 113 207 9 58 181 219 212 44 118 119 133 41 18 14 (-105)
2018-02-15 15:04:27,969 DEBUG    RFM2Pi     Discarding RX frame 'unreliable content'? 28 158 21 160 65 85 148 138 89 164 218 84 49 46 104 192 126 78 232 237 224 (-105)
2018-02-15 15:04:29,012 DEBUG    RFM2Pi     Discarding RX frame 'unreliable content'? 17 127 48 218 247 101 213 220 167 38 47 38 80 64 135 133 239 161 31 188 74 (-105)
2018-02-15 15:04:30,660 DEBUG    RFM2Pi     Discarding RX frame 'unreliable content'? 29 224 181 60 61 105 217 146 8 77 79 81 113 60 0 8 143 119 160 95 33 (-99)

Not unless you are losing data.

The “unreliable content” is anything that’s received by the RFM module but fails CRC checks, That could indeed be some valid data if you have lots of nodes completing for airtime or nodes at far flung locations or there is something generating interference and corrupting good packets etc etc But it is more likely to be next doors door bell or another incompatible device, the RSSI values at the end suggest the source is not near by (or it’s being blocked by thick concrete walls or big metal cars etc), normally “good” nodes come in at 0 to -80dB rssi.

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The low RSSI values (the more negative the number, the weaker the signal) suggest - as Paul pointed out - the “unreliable content” flags are the result of a weak signal.

At -105 dBm, the signal is only about 10-15 db above the noise floor.

You might try adding a ground plane beneath your emonTX and emonBase. Any metallic object cut to a circular shape, with a radius the same as the length of your antenna will help considerably. For best results, use one with both devices.

This thread has more info.

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My bad re. the temperature sensor. I was resetting emonBase (from the GUI) rather than power cycling the emonTx. all fine now :slight_smile: