I can also confirm that a simple USB to DB9 convertor works in combination with the Landis & Gyr E350 meter.
At first, I had a lot of trouble getting it to work with a simple FT232RL USB to serial adapter. I was using this
one, which I normally use to program Arduinos / ESPEasy modules. I only got jibberish out of Putty. I then realized that this chip needs to invert the RxD data coming in, so I tried using the FTprog program to invert the data. This seemed to work at first, but I then noticed that the chip was never programmed to invert RxD. FTprog recognized the module, I could set the data to invert, I could program the chip (or so it seemed) and FTprog even notified me: Programming succeeded! However, when I refreshed the display, the RxD invert was disabled again.
After googling a bit, I found a site
that described my problem. Apparently I bought a fake FTDI chip, which is only accessible in read mode (determined by the Windows driver). I checked the serial number of my module and indeed...it carried serial A50285BI. Although there seem to be ways of programming fake FTDI chips (check here
), I had a look in my electronics box and found an old USB to RS232 serial module
This USB to DB9 (RS232) contains the HL-340 chip (hurray: no more inverting the data either via transistor or via FTprog) and that meant I could use it straight away! So, removed the outer casing (it just slides out), soldered the +5V and GND directly to the USB connector (exactly like Cletus did) and soldered the RD to pin2 of the DB9 connector (also exactly like Cletus did). Put a 5K resistor between +5V and RD and then used Terminal
to check the incoming data. Reason why I used Terminal is because it has a nice bar on top where you can set the serial properties. I find that too cumbersome in Putty sometimes. Playing around with different settings is much easier in Terminal.
As soon as I clicked "connect" in Serial, the data started flowing in immediately! Took the module out, plugged it into the Pi3, created P1 hardware in Domoticz (do not forget to click "allow hardware for 5 minutes") and I immediately got the devices
. It's working very stable I must say! Time for a smart water meter as well