I only buy new laptops with building rs232 ports, like the HP 6550b I own. I wasted too much time on crappy USB convertors.
-----Original Message----- From: James Carlson [mailto:[email protected]] Sent: donderdag 6 september 2012 20:46 To: Discussion list for OpenIndiana Subject: Re: [OpenIndiana-discuss] stty source code Roel_D wrote: > "never" use USB-> Serial when you're testing something. There is a > huge difference between products, and the bad products behave very unpredictable. > > Don't forget that the voltage of USB is 5V MAXIMUM but can be much > lower depending on the hardware, legacy serialports need a good 5V for > a logical 1. > So communication can be disrupted by voltagedrops because the logical > 1's are not transmitted at the right voltage. Good devices have a charge pump to get the standard +/- 12VDC, such as the MAX232 or SP213. It wouldn't be too surprising to find "cheap" designs that lack the charge pump. :-< However, you are certainly right that USB serial adapters are in general all too often substantially less than ideal. In my experience, it's due to the layers of software between the actual bits on the wire and the interface exposed to the application. If you can get a real serial port (often not included in modern hardware, but usually available on an adapter board), you're far, far better off using that. (Yeah, I'm trying to be charitable with that ...) -- James Carlson 42.703N 71.076W <[email protected]> _______________________________________________ OpenIndiana-discuss mailing list [email protected] http://openindiana.org/mailman/listinfo/openindiana-discuss _______________________________________________ OpenIndiana-discuss mailing list [email protected] http://openindiana.org/mailman/listinfo/openindiana-discuss
