Multiple temperature sensors on a emonPi?

Just want to check that it is still possible to connect multiple temperature sensors, via an RJ45 Multi Breakout board, to an emon Pi, rather than having to use a Tx as well?

I was sure the earlier Pis we bought had an internal sensor but those with built-in wifi (presumably based on the Pi3) don’t appear to have that any more - is that true or am I just going nuts?

As far as I know, the emon part of the emonPi has never had an internal temperature sensor, it’s only the emonTH and emonGLCD that have had that. The emonPi and emonTx can both accept one or several temperature sensors via the RJ45 socket, and the emonTx via the terminal block also. Caution: use the correct RJ45 in the case of the emonPi.

Yes it is. The default firmware on emonPi / emonTx allows up to 6x ds18b20 temperature sensors to be connected to the RJ45 input.

All raspberry Pi’s have got a SOIC (CPU) temperature sensor, I’m not sure if it has another temperature sensor but it would be useless for ambient temperature monitoring since the whole Pi PCB gets quite warm inside an enclosure.

The enclosure does indeed make it useless, but It would be useless even if the Pi wasn’t in an enclosure.
Soon after the CPU load rises to anything above idle, the sensor will detect a temperature increase.

If the ambient temperature is less than the CPU idle temp…

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The older Pi I’m currently setting up shows Temp 1 and Temp 2 on its internal display - Temp 1 appears to reflect the probe I have connected to the RJ45 socket. I understand what you’re saying about an internal sensor being useless.

Although the emonPi display is only configured to display the first 2 temp sensors

the firmware and the subsequent payload is for 6 temp sensors

So data from up to 6 sensors would still be transmitted - without me having to change any code?

Correct, the emonTx and emonPi both support up to six sensors without any changes in firmware. More sensors can be added if the firmware is modified, we played it safe setting a 6 sensor limit. Only data from the first two sensors connected to an emonPi will show on the LCD. Data from all the sensors will be posted to Emoncms. The emonPi LCD will display the total number of sensors detected at power-up.

This is good news. At the moment I think three will be enough.

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