S0 Pulse Counter Meter
S0 (S-zero, not the letter 'O') pulse meters can be used to measure eletricity/gas/water/counter devices that provide a pulse connector.
An example of this are DIN-rail kWh-meters, those are often used for measuring the amount of energy that solarpanels have produced.
At the moment, Domoticz supports the 'S0 Pulse Counter Module (S0PCM-5)' from:
This module has 5 counter inputs.
You can use for example S0 Energy meters like the DDS-1Y.
They normally have 1000 to 2000 pulses per hour. (the more the better, more pulses = higher 'resolution')
But probably every counting device that complies with DIN 43864 / EN IEC 62053-31 standard should work, as these two standards are supported by the S0PCM-5.
Once you have the Pulse Counter Module (PCM) connected through USB and have Domoticz running, you can add the sensor at 'Setup' > 'Hardware'. Pick 'S0 Meter USB' from the dropdown menu.
Once added, you should see an option button 'Set Mode', where you can specify the type of meter and the pulses per hour.
For further selection & activation in Domoticz, it is required that at least one operational S0-interface is connected to the S0PCM. Then the S0PCM-application gets input for starting, for the operational S0-interface(s) you will see the active counter(s) of the S0PCM under 'Devices' and counter(s) can be selected for application. Without an input through an active S0-interface, the counters do not appear.
See also these forum topics for interesting background information and a useful script:
http://www.domoticz.com/forum/viewtopic.php?f=14&t=4139 for experiences
http://www.domoticz.com/forum/viewtopic.php?f=23&t=5006#p43815 for a generally applicable lua-script for upload of S0PCM-info to PVOutput.