Current Cost - Recently Updated Pages

Perl Daemon

dsc68 — Sun, 08 Nov 2009 21:42:26 CST

Here is a Perl based daemon that reads data from a CurrentCost meter and loads it into an RRD database based on Paul Mutton's RRD configuration detailed here. Works with both serial and USB devices.

#!/usr/bin/perl -w

## Reads data from a Current Cost device via serial port.

use Getopt::Std;
use Proc::Daemon;

use XML::Simple;
use Data::Dumper;
use RRDs;

sub usage {
print "\ncurrentcostd.pl - CurrentCost Daemon\n";
print "Reads data from a CurrentCost meter and populates an RRD database\n\n";
print "Options:\n";
print " -d - Debug mode. Does not daemonise and echos data to console.\n";
print " -r - RRD database to populate (required).\n";
print " -i - Input device to read CurrentCost data from (required).\n";
exit;
}

getopt('ir');

$opt_i or usage();
$opt_r or usage();

-r "$opt_i" or die "Unable to open input $opt_i\n";
-w "$opt_r" or die "Unable to open RRD file $opt_r\n";

if (!$opt_d) {
Proc::Daemon::Init;
}

open (INPUT, $opt_i) or die "Unable to open input: $!\n";

while (<INPUT>) {

if (/<ch1>/) {
my $data = XMLin($_);
if ($opt_d) { print Dumper($data); }
RRDs::update("$opt_r", "N:".$data->{ch1}->{watts});
}
}

Current Cost Cable

Anonymous — Tue, 20 Oct 2009 07:50:15 CDT

The port

The port on the back of the Current Cost is an RJ-45, the same as an ethernet port, but it won't simply connect to another ethernet device - you need a smarter cable.

The cable

Every six seconds the Current Cost outputs XML along a cable plugged into the RJ45 port as TTL-level serial data at 9600 baud working at 3.3 volts. Through some simple manipulations TTL data can be converted into RS232-compatible data. This means that we need an RJ-45 to serial cable. Once we have that, we can plug it into a normal serial-USB cable and use it anywhere that accepts USB. Hooray! You can order the RJ-45 to serial cable from Current Cost themselves or you can set about building one yourself. An alternative to this is to use an Arduino, which has native USB output so that you can do any data parsing you like before it even gets to your computer. If you also get an ethernet shield then you can connect it to your router and send information straight through to, say, twitter, without requiring a whole extra PC to be switch on!

(The latest CC128 unit outputs data at 57600 bps. So if working with Arduino forget about software serial.)

I think the cable pin outs on the referenced page may not be correct. I found that my unit (shipped Feb 09) has data on pin 8 and ground on pin 4. @paul_tanner
I can also vouch for this. My unit (Oct 09) has the dat on pin 8 and ground on 4, which is contrary to the pinout on the page/s linked above. @noisymime

Current Cost Home

Siftah — Tue, 15 Sep 2009 14:54:03 CDT

This is a place to store good pointers and collections of information which are useful to people who want to get started with their new Current Cost.

What is it?

According to currentcost.com the Current Cost is "a highly accurate second generation home electricity monitoring device." To you and me it's a consumer device for finding out how much electricity you use and how much that's costing you.

How much does it cost?

RRP £45 (but currently discounted to about £30) from ecogadgetshop.co.uk. However these have the older firmware, so buying the one from ebay is a better option.

How does it work?

The Current Cost (CC) has two parts:

a loosely-fitting clamp which you put around one of the cables leading to your electricity meter, the clamp is attached to a power pack which broadcasts readings from the clamp to...
...a display which sits on a desk or next to the telly in your living room. This plugs into the mains.

The clamp uses electromagnetic induction to measure the flow of electricity through the cable it is wrapped around, which is broadcast over (433MHz) radio to the display unit.

But such a clamp monitoring technique however does NOT show true consumed power (Watts), responding to the load's apparent power (Volt.Amps) demand, which can lead to significantly distorted readings on "reactive" loads.

Although most homes historically have resistive electrical demand, this power factor (PF) issue is of increasing importance domestically when measuring standby appliances, motors, computer power supplies etc- you will actually be consuming less energy than clamp based meters inform you about !

Find out more

The connector on the back of the Current Cost unit
Connecting your current cost to a PC or Mac using a custom cable
Connecting your current cost to an Arduino
The Current Cost XML format
Graphing the data from your Current Cost (and some more here)
Graphing Current Cost data with Munin, Python and RRDTool (including full example scripts)
Monitoring Current Cost from an iPhone webapp
Using RRDtool to maintain a round robin database
Making a power-meter using an Arduino
Ordering a data cable (RJ45-serial) from Current Cost themselves
The Current Cost ebay shop currently has serial data cables (cheaper than the other link) and the new version of the display unit.

Applications

Have something to add?

This is a wiki. Feel free to edit it via the 'Easy Edit' link above.

Current Cost Power-o-meter

Anonymous — Tue, 09 Sep 2008 07:49:35 CDT

This is the idea as shown in this flickr video:
http://www.flickr.com/photos/barnybug/2604903353/

The Arduino is connected to the CurrentCost data on pin 2.
It uses the led on pin 13 (by default the built-in led on the board) to indicated receiving data and then externally connected coloured leds on pins 9-12 for the actual meter.

This is the sketch for the Arduino. You can adjust the watt levels that trigger the leds or add or reduce the number of leds used easily.
It could be easily adapter to output the watt values on the USB serial out, for example.
Have fun!
/*
* CurrentCost serial reader
*
* BG / 23rd June 2008
*/

#include <SoftwareSerial.h>

#define rxPin 2
#define ledPin 13

SoftwareSerial mySerial = SoftwareSerial(rxPin, 3);
byte pinState = 0;
char startPattern[] = "<ch1><watts>";
char endPattern[] = "<";
int state = 0;
int pos = 0;
int power = 0;
int wattLevels[] = { 0, 200, 400, 800, 2000, 99999999 };
int wattPins[] = { 12, 11, 10, 9, 8 };

void setup()
{
Serial.begin(9600);

pinMode(rxPin, INPUT);
pinMode(ledPin, OUTPUT);

for (int i = 0; i < 5; ++i)
pinMode(wattPins[i], OUTPUT);

mySerial.begin(2400);
}

byte readByte = 0xFF;

void loop()
{
readByte = mySerial.read();
if (readByte == 0xFF) {
digitalWrite(ledPin, LOW);

}
else {
Serial.print(readByte, BYTE);
gotByte();
digitalWrite(ledPin, HIGH);
}
}

void gotByte() {
if (state == 0) {
if (readByte == startPattern[pos]) {
++pos;
if (startPattern[pos] == 0) {
// finished matching start pattern
++state;
power = 0;
}
}
else {
pos = 0;
}
}
else if (state == 1) {
if (readByte == endPattern[0]) {

// finished reading power
// light up lights
int i = 0;
while (wattLevels[i] < power) {
digitalWrite(wattPins[i], HIGH);
++i;
}

// and clear remaining
while (i < 5) {
digitalWrite(wattPins[i], LOW);
++i;
}

state = 0;
}
else {
// read another digit
power = power * 10 + readByte - '0';
}
}

}