Mendel USB and power connector
This page describes how to get power and USB into your Mendel from your computer.
Mendel needs as 12 volt power supply capable of supplying at least 5 amps. You can either buy a power brick with that specification, which will be expensive but neat, or you can hack an old PC power supply, which will be cheap but slightly scruffy.
The standard Mendel 12v power connector is a
You'll also need a USB to TTL converter. It is possible simply to buy a USB to TTL cable here.