UNI-T UT61E is one of the most famous good quality affordable multimeters. It comes with a RS232 cable for data logging. There is a USB cable available but you could convert your existing cable to USB with a few components and a FTDI adapter [source]. Also many users have attached a low energy bluetooth module inside the multimeter. I decided to build a pcb implementing both hacks.
On my pcb there is a phototranistor that receives data and sends them to the bluetooth module and to USB using a CH340 chip (USB to serial). The same chip (CH340) can be used to connect and setup the bluetooth module in AT mode with a computer.
The bluetooth module gets power from USB. I have designed the pcb to be compatible with both HM-10 and HM-11 modules (haven’t tested HM-11 yet).
I use it with UT61E Toolkit app on Android built by Jake.
Enter your email to receive the gerber files for the pcb. BOM available here.