Serial port debugging is NOT dead and I will die on this hill

Spent 6 hours last week chasing a PLC communication fault on a 20 year old boiler system because I assumed the USB-to-serial adapter was fine. Turns out the cheap Prolific chipset was the problem the whole time. Anybody else still keep a real serial port machine around for this kind of thing?

2 comments

2 Comments

allen.amy6d ago

My buddy Dave who runs an HVAC service company had the exact same thing happen last year. He was out in the middle of nowhere trying to get an old industrial chiller talking to his laptop. Three hours of swapping cables and reinstalling drivers before he gave up and drove back to his shop to grab his old Dell Latitude from 2012 with a real serial port. Booted it up and it worked first try. He still keeps that laptop in his truck specifically for those old systems.

coleman.christopher6d ago

Did you catch that article on Hackaday a few months back about the guy who reverse engineered a whole building automation system just to find out it was the counterfeit FTDI chip in his adapter? That's nuts but totally believable. I've got a stack of old ThinkPads in my garage specifically for this reason. My T420 with its built-in serial port has saved my bacon more times than I can count on old CNC machines and industrial controls. The scariest part is how many of those cheap USB adapters use counterfeit chips that just stop working after a driver update.