The zwmeter script collects energy readings from all Z-Wave energy meters in range.
Readings are collected in a round-robin fashion from all meters using the per-reading
collection interval given when zwmeter is launched. The choice of interval trades off
between data granularity and the reliability of collection.

To start data collection, specify the Z-Stick tty device and the interval, e.g.:

  ./zwmeter /dev/ttyUSB0 500

Sometimes zwread will fail to read the serial port for no apparent reason. If this
happens repeatedly, try restarting zwmeter. You may have to do this more than once.

The regular output of zwmeter consists of the following (one per line):

  * [meter-name] [meter-watts]

Meter names are specified in /etc/zwave.conf, which maps Z-Wave numeric IDs to
names you define (see zwave.conf.example). Initially, you will not know the numeric
IDs assigned to your meters - zwmeter will print out the numeric IDs in place of
names if it encounters an ID not specified in /etc/zwave.conf. Thus, when installing
a new meter, first run zwmeter and manually make note of the ID assigned to your
new meter, then add it to /etc/zwave.conf and restart zwmeter. You should not assign
ID 1, as this should be used by the Z-Stick.

In addition to regular readings, zwmeter will output the following 'special' reading:

  * zwround [duration-ms]

This gives the duration between subsequent readings of the same device (i.e., the
length of a polling round). This gives an indication of whether the data collection
interval is sufficiently large to ensure reliable readings.

Output lines not starting with * are debugging or warning messages. zwmeter will
continue executing until terminated, at which point it will stop zwread as well.

If something is not working, it may be helpful to invoke zwread directly (in the same
way as zwmeter). This will dump the raw output of OpenZWave, which may be helpful
in debugging.

Copyright (2012) by Sean Barker (sbarker@cs.umass.edu)