The emonTx V3.4 is a low power wireless energy monitoring node designed for monitoring AC electrical power on (up to) 4 separate (household/building) circuits using non-invasive clip-on CT current sensors and an AC-AC Voltage adapter to provide a voltage signal for full Real Power calculations and AC VRMS readings.
The emonTx is designed to be used in conjunction with an emonPi or emonBase web-connected base-station to post data online to Emoncms.org and/or log data locally to the Raspberry Pi's SD card. Alternatively it is possible to add Wi-Fi directly to the EmonTx with a ESP8266 WIFI adapter.
To get started visit the OpenEnergyMonitor Setup Guide.
Optional: The EmonTx can be optionally powered by 3x AA batteries. Select the 3x AA battery holder option above if you wish to use this option. In order to preserve battery life the EmonTx needs to go to sleep between readings, we upload our discrete sampling firmware to the EmonTx to achieve this rather than the standard continuous sampling firmware. The discrete sampling firmware is less accurate than the continuous sampling firmware so its worth only selecting this option if you need to power the EmonTx from battery power.
The emonTx with the default firmware is suitable for use on a single-phase supply, or on a split-phase supply, or on one phase of a multi-phase supply. Firmware is available which will allow for 'approximate' 3-phase monitoring (described here), which we can upload prior to shipping if it is requested.
Includes (as standard)
Note: CT sensors give a much better reading of instantaneous power than pulse counting, we recommend using a CT wherever possible. When using the pulse counting method to monitor power from a utility meter the sample rate is limited to the number of pulses; at low power values the interval between pulses can be extremely long.
Multiple emonTx unit's can operate on a single RF network posting to a single emonPi / emonBase web-connected base station (Raspberry Pi + RFM69Pi), each emonTx on the same network must have an unique node ID. The nodeID can be selected at time of purchase or set using the on-board DIP switch to toggle. If more than two emonTx's are required on the same network then further nodeID values can be set via RF node ID serial config.
DS28B20 Temperature sensors can be connected to either the RJ45 sonnector or wired into the terminal block. Only genuine Maxim DS18B20 sensors should be used (as sold via the shop), incompatabilty with non genuine sensors has been reported. DS18B20 can be wired into the terminal block using screw terminals:
2 - 3.3V Power
3 - GND
6 - 1-wire data
The emonTx is Arduino compatible: updated/customised firmware sketches can be uploaded using Arduino IDE and a USB to UART cable (available separately)
The emonTx comes pre-loaded with the EmonTxV3CM Continuous Sampling firmware as standard for single phase operation. If the battery holder is selected we will upload the low power discrete sampling firmware see note above.
Customised firmware sketches and be easily uploaded from the PlatformIO / Arduino IDE and a USB to UART cable (not included).
Firmware repositories:
Note: even though the unit is pre-programmed we recommend a USB to UART cable to keep at hand for debugging and updating / customising firmware using Arduino IDE.