Path: csiph.com!news.mixmin.net!eternal-september.org!reader01.eternal-september.org!.POSTED!not-for-mail From: Paul Rubin Newsgroups: comp.arch.embedded Subject: Re: Shared Communications Bus - RS-422 or RS-485 Date: Wed, 02 Nov 2022 17:36:54 -0700 Organization: A noiseless patient Spider Lines: 21 Message-ID: <87k04c27rt.fsf@nightsong.com> References: <6b8c6b92-a2ca-4849-ba68-f03060bc41fcn@googlegroups.com> <871qql2ezq.fsf@nightsong.com> <85415d13-1a8c-4f07-8bbf-46564346cf36n@googlegroups.com> MIME-Version: 1.0 Content-Type: text/plain Injection-Info: reader01.eternal-september.org; posting-host="1b825525f395ae7931c686911d6726ac"; logging-data="1359306"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX18EIOh4Wifq2xOLNNGdeULh" User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) Cancel-Lock: sha1:/R7Hbb8xnxbNahQnW0FUNp4pMsI= sha1:77DwQL2ZifS9Hf2QtTdabJzM7FQ= Xref: csiph.com comp.arch.embedded:31308 Rick C writes: > I'm lost. How is this any better? The data collection is running on > the PC, so there still has to be communications... All they would be > doing is acting as a serial port concentrator. They went out 40 years > ago! Well, I always like doing stuff in software instead of hardware. Serial port concentrators are still around and I posted a link to one in your other thread. It seems like a reasonable approach too. Oddly, a quick web search doesn't find any big cheap serial to ethernet ones, but maybe you could use USB hubs and FTDI-like cables. The idea of using an MCU is to move almost everything speed critical away from the PC. The MCU only has control the FPGA's and transfer transfer digested data upwards to the PC. By having some fanout you could potentially control 1000s of UUT instead of 80 from a single PC, without having to build anything special. It would just mean plugging some off the shelf boxes together, and writing some code. You're more comfortable with hardware than I am, so maybe that approach has less attraction for you than it does for me.