Archived Forum

"First question: how can I understand if the EmonTx contains its firmware?"
The emonTx V3 should contain the default sketch. Until you connect the Arduino IDE and look at the output of the serial port, you can only know that it has a sketch loaded if the LED is programmed to blink. I think you have a sketch loaded.
"What does [the LED] mean?"
See here

"when I plug power AC nothing happens, the led remains switched off."
Do you have link JP2 connected? The ac-ac adapter only works as a power supply when JP2 is connected. Is your ac-ac adapter working? Does it give you approximately 11 V ac?

"why I can’t see EmonTx into “Serial Port” options in Arduino IDE?"
Have you installed the Arduino IDE and drivers? See: http://openenergymonitor.org/emon/buildingblocks/setting-up-the-arduino-...

Hi Robert,

thank you for your answer.

"when I plug power AC nothing happens, the led remains switched off."
Do you have link JP2 connected? The ac-ac adapter only works as a power supply when JP2 is connected. Is your ac-ac adapter working? Does it give you approximately 11 V ac?

Yes, when I plug my AC-AC adapter the JP2 is connected but nothing happens, LED remains off. I understood that my ac-ac adapter is 9 Volt and 400mA and this is a problem: read here that maximum current should be 60 mA. But I think that EmonTx has not damages since when I use batteries or miniUSB cable led switch on properly (The red LED indicator will illuminate for 10s then flash once then never to flash again if powering from a DC source).

"why I can’t see EmonTx into “Serial Port” options in Arduino IDE?"
Have you installed the Arduino IDE and drivers? See: http://openenergymonitor.org/emon/buildingblocks/setting-up-the-arduino-...

Yes I installed all drivers but the FTDI Drivers since I don't have USBtoUART cable.
I don't have USB to Serial neither so I connect PC with EmonTx with miniUSB cable only. Probabily is not possible to see the EmonTx in Serial Port in Arduino IDE in this way.

Anyway, I configured my Raspberry to send data to emoncms.org (using my account's write api key) but under input tab I can't see expected data.
How can I test if Raspeberry receive data from EmonTx?

Thanks

"when I use batteries or miniUSB cable led switch on properly"
That proves that most of the emonTx is working correctly. Where did you buy your ac-ac adapter? Is it correct for your mains voltage? Can you measure the actual voltage that it supplies when it is connected to your emonTx? You should measure approximately 11.5 V ac between GND and the ac input labelled "9V AC". Do you measure 3.3 V dc between GND and JP2?

"I connect PC with EmonTx with miniUSB cable only"
The USB cable supplies ONLY power to the emonTx. There is NO data connection. You MUST use the FTDI connection and a programmer.

"How can I test if Raspeberry receive data from EmonTx?"
I don't know about the Raspberry Pi. Someone else will have to answer this.

Thank you Robert, I successfully completed the installation!

What was the problem with your AC-AC Adapter?

It uses 400mA whereas the maximum for EmonTx V3 is 60 mA.

So I just use batteries by now and everything works. If I'll need a more precise measure I'll buy an ac-ac adapter from OpenEnergyMonitor Shop
 

I think there's some confusion there. The AC adapter will not use 400 mA, most likely, if it says 400 mA on it, it will be capable of supplying 400 mA, the EmonTx V3 draws only about 12-13 mA average (22 mA rms or 60 mA peak) in its normal configuration. So I suspect your adapter is not giving a high enough voltage for the on-board regulator to work. I've just rerun the design simulation with no additional load, but otherwise with worst-case components, and the power supply fails when the input is less than 7.2 V rms. We strongly recommend (and the input circuit was only designed for) the shop adapter which gives 9 V rms at full rated output and around 10.5 V rms when used with the emonTx.

Sorry Robert, you're completely right.

I will use EmonTx with batteries for my project so I was not considering the solution with ac-ac adapter anymore, so I didn't think about this problem and I wrote the first thing had come in my mind: a stupid thing!
Sure, 400 mA is the max current the adapter can supply and not a fixed value. The current depends on the attached device.

When I have time I will try again with others ac-ac adapters to better understand the problem, then I will write here if I have news.

(I've added the rms current in my post above.)
As the Wiki says, the input circuit and correct measurement of the voltage is critically dependent on the AC adapter. The component values were carefully selected against the properties of the Ideal adapter so that the current pulse, which occurs as the reservoir capacitor charges, did not unacceptably disturb the voltage measurement.