USB to UART programmer for uploading Arduino software sketches and reading serial data from from all OpenEnergyMonitor hardware units: emonPi, emonTx, emonTH etc. 

No driver required for Linux. Mac / Windows drivers can be downloaded below.

Micro-USB cable is required, sold separately.

Soldering required (see the 'Assembly Guide' below). A pre-assembled unit is available for a small fee - just select the relevant check-box when ordering.

Technical 

• Low supply current :10mA 
• Supported baud rates: 300 bps to 3 Mbps 
• Power output to external logic 5V/3V3 (set by a removable jumper)

Includes

• 1 X USB- serial UART dongle 

Does not include

• Micro USB Cable

Assembly Guide 

All the information needed to assemble the programmer is on the FTDI data sheet: https://www.ftdichip.com/Support/Documents/DataSheets/Modules/DS_LC231X.pdf

The 6-pin right-angle connector in position CN11 is the correct one for the emonTx & emonTH. You should fit the connector so that it is on the same side as the USB socket.
Be sure to select the correct voltage with CN14: 3.3 V. (this is the default.)

See Figure 2 on the data sheet for the pin identification on the FTDI module - GND is at the opposite corner to the voltage selector.
The GND pin on the emonTx is marked on the front panel - it is nearest to the RJ45 socket. Therefore, the LEDs will point upwards when the module is plugged into the emonTx.
The GND pin on the emonTH is nearest to the centre, and is marked on the PCB.

Drivers 

No device drivers required for Linux.

Mac & Windows: FTDI device drivers and installation guides.

Documentation

Data sheet: LC231X datasheet.