Introducing emonTx V3.4

Now shipping later this week in the shop is an updated version to the emonTx V3. This is a relatively minor update feature and form factor wise, most users probably won't notice the difference. However when hardware is involved, no update is a minor update!

emonTx V3.4 is now available from the OpenEnergyMonitor Shop

The main changes  are under the hood; the ATmega328 Arduino compatible microprocessor is now is now laid down directly on the PCB. This will help with manufacture and give us a few extra I/O to pay with that were inaccessible on RFu328 module that we used on the original emonTx V3.2. The changes also bring us back in line with JeenNode hardware (IRQ and INT connections) which allow us to use the latest RF12 JeeLib library to support the RFM69CW (see separate post).

emonTx V3.4 Installed

emonTx V3.4 - production units will have battery holder fitted - omitted for photo to show components


New features on emonTx V3.4 over V3 shown in bold:
  • Measure AC Apparent Power, AC Real power* and AC RMS voltage*
  • 3 x single-phase CT current sensor inputs (100A / 24KW @ 240V max)
  • 1 x high sensitivity single-phase CT current sensor input channel (18.8A / 4.5KW @ 240V max)
  • 1 x RJ45 input for connecting DS18B20 temperature sensors
  • Single AC-AC adapter can power the unit and provide AC voltage measurement
  • An on-board 3x AA battery option with remote monitoring of battery voltage
  • Terminal block access to power rails, digital and analogue I/O and IRQ port for connecting pulse counting sensor / DS18B20 temperature / Aux sensors
  • DIP switch selection of RF node ID and 240V/110V AC adapter selection, see #DIP Switch Config
  • SMA antenna included as standard 
*when AC-AC voltage adapter is connected

emonTx as part of the OpenEnergyMonitor system
The emonTx V3.4 uses an edge SMA connector with an SMA antenna included as standard. We have standardised on 433Mhz (see forum post). The emonTx V3.4 supports and will eventually ship with the new RFM69CW module, this module is backwards compatible with RFM12B. However due to sourcing and lead time issues we have had to use RFM12B on the first batch of 500 units of emonTx V3.4 (now in the shop). When the RFM69CW is used a RSSI (Received Signal Strength Indicator) will appear in emoncms giving indication of signal strength. 

emonTx V3.4 with RFM69CW and edge SMA connector 
The emonTx V3.4 has the addition of an RJ45 socket to allow ease of connecting multiple DS18B20 temperature sensors. Screened RJ45 cabling (Ethernet) is commonly available as well as RJ45 splitters and extenders. This makes a quick and easy way to wire up a house / heat-pump etc for temperature monitoring. Power, GND, IRQ, ADC and PWM I/O's are also available through the RJ45 connector, see wiki for pinout and technical details.

Note: the RJ45 connection is not Ethernet, TCP network switches and routers should not be used 

RJ45 connector used with RJ45 terminal breakout for connection of multiple encapsulated DS18B20 temperature sensors, DS18B20 temperature sensors are also available wired directly on RJ45 connector

DS18B20 Temperature Sensor on RJ45

Certification & Environmental

The emonTx V3.4 is EMC compliant, CE certified. 

The unit is manufactured and assembled in the UK using lead free processes, with RoHS and conflict material free components. The enclosure is made in the UK using recyclable aluminium and recycled acrylic plastic is used for the front and rear fascia. 


Getting Started Guide
emonTx V3.4 Technical Documentation Wiki 
emonTx V3.4 open-source hardware design available on GitHub
emonTx Arduino compatible firmware GitHub
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