SABRENT USB-C to DB9 Serial RS-232 Adapter Cable 6FT, Prolific PL2303GS Chipset, USB 2.0, 1bps-12Mbps Baud Rate, for POS Terminals, Modems, GPS, Industrial Devices (CB-D9C6)

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GOOD: • Genuine Prolific PL-2303 chipset works with standard Prolific drivers • Directly attaches to devices that use a PC-style nine-pin serial connection • Reasonably long cord means you may be able to make the connection with this cord alone • USB-C interface ideal for Mac laptop users who need to make serial connections (like systems administrators) • Shell has a URL in reasonably large type that takes you straight to the driver download page, and a QR code that takes you to the product page NOT SO GOOD: • Translucent cord cover is relatively high-friction, and in the past, I've found this sort of material doesn't age well • DB-9 shell has hard square edges that aren't comfortable to hold while using, and the inexpensive plastic material is slick: the design makes it harder to grip than it needs to be • You'll still need a dongle to connect to anything that isn't designed to be plugged directly into an IBM PC style DB-9 serial port BOTTOM LINE: A good but not perfect specialty tool for people who need to connect modern laptops to legacy serial equipment.

This USB/Serial adapter is fine for most basic applications, like accessing console ports, playing with an old modem, talking to vintage equipment, etc. It fails to deliver the claimed maximum speed of 12 Mbps. It does seem to correctly implement the full complement of RS232 signals as commonly found on DB9 connectors, properly handling DTR and RTS (though it does not seem to implement internal flow control, it just passes the signals through). The voltages don't quite meet the full RS232 spec, it only delivers +/- 7V or so, but that's sufficient for most purposes. Works fine at common bit rates up to 230400, above that things get quite wonky. Driving an oscilloscope 10x probe (high impedance) directly off the DB9 connector, the signal is still recognizable at 1Mbps, and would probably decode correctly with a hardware UART. Beyond that, it gets pretty useless. Setting it to 12Mbps is accepted, but the output just looks like a molehill, one slope-sided pulse with no data content. Putting a little load on it seems to make it worse rather than better. It looks like the RS232 driver IC in here just doesn't have the power to drive the lines either high or low with adequate slew rates to achieve high bitrate. It's probably the Sipex SP213EHCA that's referenced in the PL2303 datasheet -- that's only rated up to 500Kbps, which seems about right. Interestingly, the front of the package says "USB-C 5 Gbps" on it, and that's not, either. It's only a USB 1.1 connector, and it registers as a Full Speed (12Mbps) device. Which is fine, considering the application. All in all, it works, and I'll probably find a use for it occasionally if i want to talk to some ancient device using the serial terminal app on my phone. But for a professional, you can probably find a better one, and if you need anything over 500Kbps, forget it.

Does not transfer data,

This is a very handy USBC to DB9 rs-232 adapter cable. I use this with some old amateur radio equipment and it helps to facilitate my continued use of my old gear with new computers. No problems or issues. Great cable and seems to be a good value overall. Recommended.