6. Add Energy Sensing Node(s)

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Additional energy monitoring nodes

Additional energy monitoring nodes can be added if more AC circuits require monitoring or the monitoring location of the circuits is inconvenient to access power outlet and network connectivity.

The emonTx is a remote sensor node. Data is transmitted to an emonPi or an emonBase via a low power 433MHz radio.

Note: as an alternative option, the emonTx can be used ‘standalone’ with an ESP8266 WiFi module running EmonESP to post directly to Emoncms without an emonPi / emonBase. See Using the EmonTx v3 with the ESP8266 Huzzah WIFI module


  • Energy monitoring add-on node
  • Optional add-on if more then two circuits need to be monitored or if WiFi / Ethernet connectivity is not available at utility meter
  • RF Range is approximately similar to home WiFi and can be affected by obstacles e.g. thick stone walls
  • Up to 2x emonTx can be connected to a single emonPi *

* More than 2x emonTx units can be connected to a single emonPi / emonBase with manual change of RF nodeID. This can be done This can be done via serial node ID config


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Hardware Setup

1. DIP Switch Config

  • If more than one emonTx is to be used with the same base-station set the node ID using the on-board DIP switches.
  • USA mode can also be toggled using DIP switches

2. Install Sensors

3. Power Up

  • Power emonTx directly from an AC-AC adapter (additional DC adapter not required)
  • Or alternatively power via 3 x AA batteries.
  • All sensors should be connected before power up

4. Indicator LED

  • Illuminates solid for a 10 seconds on first power up
  • Flash multiple times to indicate an AC-AC waveform has been detected (if powering via AC-AC adapter)
  • Flash once every 10s to indicate sampling and RF transmission interval

An emonTx can be powered by 3 x AA batteries; however, if possible, it is recommended to power the unit with an AC-AC adapter to provide an AC voltage reference for more accurate Real Power and VRMS calculations.

Base-station Emoncms Setup

The emonTx is compatible with emonPi / emonBase. RF transmission from the emonTx should be picked up automatically and data should appear in local Emonms Inputs page.

If Remote logging has been setup, data will also be posted to Emoncms.org.

1. Log inputs to feeds

Note: if using more than two emonTx units (with custom RF node ID or modified firmware) emonhub.conf node decoders will need to be setup.

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