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Hi Ricardo

You will need an emonTx to connect your sensors and perform the calculations,

Although you could connect this to your laptop using a ftdi usb cable and monitor the serial output but to be honest you would be far better of using a pi emonbase. It will consume very little power being on 24/7 and then emonCMS is designed for monitoring and analyzing energy data, it doesn't cost anything and it can produce csv files if that's what  you want.

Using a pi you can have a local copy of emoncms or post to emoncms.org (or both)

Paul

The problem with an Arduino microprocessor is there is very little memory available for data storage after the program for taking the measurements has been loaded, therefore doing as you suggest means that you must keep your laptop connected all the time (or as a minimum, all the time that you want to gather data). If that is what you want, then you need either an Arduino board or an emonTx (but you will not use the RFM12B radio module) and you can transfer the data to your laptop via the serial FTDI port.

Reports suggest that you will get better accuracy if you use an emonTx V3, in preference to an Arduino board. We think the reason is the emonTx has a better design of the analogue part than the Arduino board. But if you need more than 4 current inputs, then you probably have no option but to use an Arduino.

If you use an Arduino, you will need to design and construct your own signal conditioning front end circuits, using the basic information in Building Blocks.

Paul suggests connecting an Arduino or emonTx directly to a Raspberry Pi, to which you add a hard disk drive. How to connect is here: http://openenergymonitor.org/emon/node/3872  If you do this, the Raspberry Pi and HDD replace your laptop.

Hi

I was hoping i didn't have to spend too much money since to monitor all outputs from the main panel I'll need 9 current inputs and that means 2/3 sensors. That would be too much money. But I'll probably be better served with the whole package. Maybe i can monitor 4 at a time.

So, if i buy a Raspberry Pi (Model B) - Web-connected Base Station and a emonTx V2 - Energy Monitoring Transmitter Unit - Kit along with some CTs and sd card and a ftdi cable, i should be good to go, right?

Ricardo

The emonTx V2 will give you 1 voltage and 3 current inputs. However, if you add headers, and your own input circuitry, more inputs are available. The ports diagram here shows that AIO4 & AIO5 are free, you can add a current input circuit to each giving you 1 voltage and 5 current inputs in total. We have found that the emonTx V3 performs slightly better than the V2, therefore you might want to consider the V3 instead. I have not tried this, but you might be able to add the input circuitry and use ADC5 on the V3 to get 5 current inputs.

If you want to measure real power, you need to add an AC-AC adapter to your list, otherwise you will need a 5 V USB power supply and appropriate cables for your emonTx, or use batteries. And don't forget a box, power supply and cables (power, Ethernet) for your Pi.

Hi.

You say that AIO4 & AIO5 are free, but in the board there are more AIO. Why can't they be used? 

Thanks

Are there? Where? See P.250 of the Atmel ATmega48PA/88PA/168PA/328P data sheet, section 32.1.

Just one point to note, I believe the emonTx V2 kit will not become available again, ever. The PCB will be available only until all stocks have gone.

I already have the emonTx V2 and it works ok with a laptop registering the values.

I'm planning on buying a base so that i don't have to have a laptop nearby. Just wanted to add more sensors