I plugged a PL2303TA (first time I ever used it) into an Arduino MKR 1010 Wifi Serial1 (pin 14 & 15, plus GND) and tried getting some communication.
Serial1.write on the Arduino triggered reception of data on my PC, but Serial1.available() never returned anything. In itself, since I could receive on the computer, that tends to confirms proper connection. However, just in case, I did reverse RX & TX on the Arduino side, still got nothing.
When I started suspecting the adapter, I replaced it with another (also first usage ever), same result. I think plugged it onto a logic analyzer to see that nothing would get captured on TX.
I ended up replacing the PL2303TA with a different (FTDI based) USB to UART adapter, plugged the same signals, it instantly worked. And later for debugging purposes I plugged in on the same logic analyzer, which could “intercept” data in both direction without problem.
So now my wonder is, is there anything out of wiring these 3 cables I should have done?
Cheers for posting a descriptive photo, and detailed info on your troubleshooting so far.
My first though was control signals, as some FTDI devices need those pins pulled around to work, but it seems those aren’t there/needed on the prolific part.
Glad you’ve done this, it would be my first step too. The only thing that concerns me is when you reversed the RX/TX pins, as this would be two low-impedance pins potentially trying to drive one line to different values, so perhaps some of your devices have damaged output drivers.
Would you be able to do one last test for us before we declare these faulty? Could you grab one that hasn’t had its TX pin connected in an unconventional way and see what your LA thinks of it?
Once we’ve got that we can be pretty sure this is a hardware fault, and move on to an RMA.
I just did a test with the logic analyzer again on 2 of them (mostly because I’m not sure which has had its TX connected to the Arduino TX at some point, so with 2, 1 is necessarily undamaged), TX is held up high constantly on both.
Cheers doing that final test for me, I think it’s pretty clear that it’s not a driver issue since you can receive data, so that leaves a hardware fault (barring anything that happened whilst wiring these up).
Reach out via email and we’ll sort out a store credit for you.
