Metering Musings

I've been intermittently trying to get our smart metering datafeed out to to a server for better logging, but I don't want to run a 300W PC to tell me my baseload in the house is 300+N W. There are several clamp meter / arduino designs thanks to the folks like OpenEnergyMonitor and Nanode, but things should be easier as there's a nice serial out already documented by ERDF (there's also the upcoming 'linky' interface but we're still on old-school)

How much does all this malarkey cost -- off the shelf there are USB opto interfaces, but they're about €50 each (erk) I originally purchased an arduino datalogger shield (€40 + an arduino) hoping to use it with a nanode, but I  didn't get ethernet sending working (even after the slight hardware mod) - possibly due to known issues with stash depletion

So - where do we go (cheaply) from here? a R-Pi gives me cheap hardware with more stable ethernet but I'd have to interface in the opto tty interface (gpio? usb?) as there's no onboard serial. Plan B is to use my bifferboard and use the console interface: small, yep. Low power, yep. Decent ethernet and OS (openwrt) - yes.

So, time to order some parts and get down to prototyping...

Teleinfo update

I''ve been using a teleinfo shield on a nanode to try and datalog our electricity usage, but the logging to the CSV file kept truncating as if the arduino had locked up. There have been discussions elsewhere that this may be related to the code in arduino 1.0 so I decided to rewrite a step at a time to try and debug the problem.

Some observations on the way:

1) having to flip a jumper over on the shield between programming and run is *very* annoying in a cold garage, so I'm going to rewire it slightly to use SoftwareSerial on a spare input (leave JP1 open and wire from one side of it to a spare pin) - I already have a link since the shield tries to use DIG6 by default which is used by the red LED on a nanode.

2) the arduino IDE doesn't like anything other than 8N! on the serial monitor. close it and use kermit. if you can't read serial with kermit, then it's *very* broken :-)

3q) our usage is going UP not down :-( -- lowest figure I managed to get the baseline to was 340VA

With a very simple logger

    Serial.print(char(meter.read()));

I can stream the output to a kermit session log as

^B
ADCO 040222048573 <
OPTARIF BASE 0
ISOUSC 30 9
BASE 040912359 ,
PTEC TH.. $
IINST 002 Y
IMAX 029 J
PAPP 00340 (
MOTDETAT 000000 B^C

next trick is to try and get the processing organised into blocks and validate the checksum, but my code doesn't seem to detect the stx/etx properly

void loop() {
if(meter.available()>0) {
  if((c = meter.read()) == 02) {     // start of block
    Serial.println("DEBUG: Start Loop");
    while((c = meter.read()) != 03) {      // Loop until end of block
      Serial.print(char(c));
    }
    digitalWrite(LED, LOW); // Flash LED
    delay(50);
    digitalWrite(LED, HIGH);
  }
}
}

so mode debugging called for. Once thats done, then I'll send the values to an emon style display over rfm12b

Metering

So I finally got round to wiring in the 'Teleinfo' shield into my EDF meter (see my earlier post for more info) and left it running while we're away. Hacked up an initial couple of graphs using trusty gnuplot: exhibits A and B -

It's rather easy to spot where the fridge-freezer kicks in, but more worrying is the fact that the baseline never dips below 170VA. The only things that should have been running in that time was my via-eden server, with one HDD, the livebox and samknows monitoring box. I suspect I need to investigate more.

Made a minor hack to the shield as digi-6 is used by the LED on a nanode - but digi-7 is free.
Details were tweeted over here. Next up is to get it sending the info out to main box (well, another nanode or my bifferboard) and spitting to pachube and / or a jeelabs display board.

PoE Network controlled signage

I may have a requirement for several 'remote controlled' illuminated signs. (where remote could be network driven) - These aren't Scrolling LED 'calls in queue' type ones, but more the warning 'Laser on', 'Mic Live', 'Conveyor Running' type ones.

Normally these things seem to be driven directly from some local switchgear or output, but what if you want to gather status centrally , or illuminate the sign depending on some remote sensor (be it a web tsunami alert or the boss' car being picked up on the ANPR at the gate)

Cue a quick hacky prototype: Take one nanode and use the digital outputs to drive a mosfet to switch some cheap LED strips from IKEA. So far so good, but that requires a 12v (since thats what the strips use) supply. The nanode can take that on the screw inputs if you add a heatsink to the reguator, but I'd rather get rid of the PSU alltogether: cue a cheapo 802.3af PoE splitter from TP-Link, and I have the whole lot driveable off one RJ45 cable.

Onwards to software, and it looks like bitlash / restuino look useful (esp if I get the whole lot working with DHCP too).

Anyway, with a range of lighting areas possible (thanks to addressable outputs on the nanode) per display, the option to have a nice facia with multiple 'zones' illuminated is possible. Now to find a nice case...

nanode built!

One successful evening of soldering, and lo, I have a working nanode. Started off nice n basic with the resistors, but overall a pretty simple pcb to assemble:

Plugged it in, and lo, blinky LED. Have since flashed with the EtherShield Drivers and its happily getting an IP address. now for some pachube / twitter / other integration...