1. bobmc

    HOWTO: Test RS232 and RS485 adapters

    Once upon a time, PCs needed RS232 serial ports for modems, printers, and terminals. These use-cases are mostly obsolete but now they can be used for factory PLCs, IoT devices, and asset management. RS485 can operate sensor hundreds of feet from the host (master) computer. Many PCs omit...
  2. S

    driver development for StarTech/Rayon serial expansion cards

    [ed: My apologies if I've chosen the wrong forum. I've been with FreeBSD for a long time, but I've only participated online sporadically.] Here's my situation. I have in my possession three quad RS422/RS485 expansion cards from (which seem to also have some association with...