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Groups > comp.arch.embedded > #31541 > unrolled thread
| Started by | Rick C <gnuarm.deletethisbit@gmail.com> |
|---|---|
| First post | 2023-01-17 07:24 -0800 |
| Last post | 2023-03-29 00:44 -0700 |
| Articles | 20 on this page of 155 — 18 participants |
Back to article view | Back to comp.arch.embedded
Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-01-17 07:24 -0800
Re: Boxed MCU with RS-232 Port Paul Rubin <no.email@nospam.invalid> - 2023-01-17 11:31 -0800
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-01-17 12:19 -0800
Re: Boxed MCU with RS-232 Port Paul Rubin <no.email@nospam.invalid> - 2023-01-17 13:07 -0800
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-01-17 13:29 -0800
Re: Boxed MCU with RS-232 Port Paul Rubin <no.email@nospam.invalid> - 2023-01-17 14:04 -0800
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-01-17 14:47 -0800
Re: Boxed MCU with RS-232 Port Paul Rubin <no.email@nospam.invalid> - 2023-01-17 15:32 -0800
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-01-17 15:44 -0800
Re: Boxed MCU with RS-232 Port Paul Rubin <no.email@nospam.invalid> - 2023-01-17 16:04 -0800
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-01-17 17:32 -0800
Re: Boxed MCU with RS-232 Port Paul Rubin <no.email@nospam.invalid> - 2023-01-17 20:02 -0800
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-01-17 20:24 -0800
Re: Boxed MCU with RS-232 Port Paul Rubin <no.email@nospam.invalid> - 2023-01-17 20:56 -0800
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-01-17 22:30 -0800
Re: Boxed MCU with RS-232 Port Paul Rubin <no.email@nospam.invalid> - 2023-01-18 00:37 -0800
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-01-18 04:43 -0800
Re: Boxed MCU with RS-232 Port Paul Rubin <no.email@nospam.invalid> - 2023-01-18 14:19 -0800
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-01-18 23:15 -0800
Re: Boxed MCU with RS-232 Port Paul Rubin <no.email@nospam.invalid> - 2023-01-19 12:21 -0800
Re: Boxed MCU with RS-232 Port Andrew Smallshaw <andrews@sdf.org> - 2023-01-18 12:15 +0000
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-01-18 04:55 -0800
Re: Boxed MCU with RS-232 Port Andrew Smallshaw <andrews@sdf.org> - 2023-01-18 13:22 +0000
Re: Boxed MCU with RS-232 Port Andrew Smallshaw <andrews@sdf.org> - 2023-01-18 13:28 +0000
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-01-18 06:20 -0800
Re: Boxed MCU with RS-232 Port David Brown <david.brown@hesbynett.no> - 2023-01-18 10:04 +0100
Re: Boxed MCU with RS-232 Port Theo <theom+news@chiark.greenend.org.uk> - 2023-01-18 16:18 +0000
Re: Boxed MCU with RS-232 Port Paul Rubin <no.email@nospam.invalid> - 2023-01-18 14:10 -0800
Re: Boxed MCU with RS-232 Port Theo <theom+news@chiark.greenend.org.uk> - 2023-01-19 10:29 +0000
Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-01-19 05:41 -0700
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-01-19 10:00 -0800
Re: Boxed MCU with RS-232 Port Paul Rubin <no.email@nospam.invalid> - 2023-01-19 12:42 -0800
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-01-19 14:10 -0800
Re: Boxed MCU with RS-232 Port Paul Rubin <no.email@nospam.invalid> - 2023-01-19 16:16 -0800
Re: Boxed MCU with RS-232 Port Grant Edwards <invalid@invalid.invalid> - 2023-01-19 16:07 +0000
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-01-19 10:13 -0800
Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-01-19 14:51 -0700
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-01-19 10:06 -0800
Re: Boxed MCU with RS-232 Port Theo <theom+news@chiark.greenend.org.uk> - 2023-01-20 13:03 +0000
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-01-20 06:28 -0800
Re: Boxed MCU with RS-232 Port Paul Rubin <no.email@nospam.invalid> - 2023-01-20 19:14 -0800
Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-01-20 20:41 -0700
Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-01-21 05:05 -0700
Re: Boxed MCU with RS-232 Port Theo <theom+news@chiark.greenend.org.uk> - 2023-01-21 10:53 +0000
Re: Boxed MCU with RS-232 Port Herbert Kleebauer <klee@unibwm.de> - 2023-01-20 19:17 +0100
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-01-20 12:37 -0800
Re: Boxed MCU with RS-232 Port Dimiter_Popoff <dp@tgi-sci.com> - 2023-01-20 23:02 +0200
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-01-20 14:08 -0800
Re: Boxed MCU with RS-232 Port Dimiter_Popoff <dp@tgi-sci.com> - 2023-01-21 01:38 +0200
Re: Boxed MCU with RS-232 Port antispam@math.uni.wroc.pl - 2023-01-21 01:58 +0000
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-01-20 18:44 -0800
Re: Boxed MCU with RS-232 Port antispam@math.uni.wroc.pl - 2023-01-21 20:02 +0000
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-01-22 17:12 -0800
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-02-03 09:22 -0800
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-02-03 10:04 -0800
Re: Boxed MCU with RS-232 Port Dimiter_Popoff <dp@tgi-sci.com> - 2023-03-26 22:24 +0300
Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-03-27 02:27 -0700
Re: Boxed MCU with RS-232 Port pozz <pozzugno@gmail.com> - 2023-01-20 08:54 +0100
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-01-20 01:03 -0800
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-22 12:18 -0700
Re: Boxed MCU with RS-232 Port Paul Rubin <no.email@nospam.invalid> - 2023-03-22 20:35 -0700
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-22 23:26 -0700
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-22 23:28 -0700
Re: Boxed MCU with RS-232 Port Theo <theom+news@chiark.greenend.org.uk> - 2023-03-23 10:06 +0000
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-24 00:59 -0700
Re: Boxed MCU with RS-232 Port Paul Rubin <no.email@nospam.invalid> - 2023-03-23 09:00 -0700
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-24 01:03 -0700
Re: Boxed MCU with RS-232 Port Paul Rubin <no.email@nospam.invalid> - 2023-03-23 08:54 -0700
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-24 01:02 -0700
Re: Boxed MCU with RS-232 Port Paul Rubin <no.email@nospam.invalid> - 2023-03-24 01:43 -0700
Re: Boxed MCU with RS-232 Port Hans-Bernhard Bröker <HBBroeker@t-online.de> - 2023-03-24 12:44 +0100
Re: Boxed MCU with RS-232 Port Theo <theom+news@chiark.greenend.org.uk> - 2023-03-24 14:20 +0000
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-24 08:08 -0700
Re: Boxed MCU with RS-232 Port Theo <theom+news@chiark.greenend.org.uk> - 2023-03-24 16:23 +0000
Re: Boxed MCU with RS-232 Port Paul Rubin <no.email@nospam.invalid> - 2023-03-24 13:42 -0700
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-24 14:31 -0700
Re: Boxed MCU with RS-232 Port Paul Rubin <no.email@nospam.invalid> - 2023-03-24 18:19 -0700
Re: Boxed MCU with RS-232 Port Paul Rubin <no.email@nospam.invalid> - 2023-03-24 18:22 -0700
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-24 18:34 -0700
Re: Boxed MCU with RS-232 Port Paul Rubin <no.email@nospam.invalid> - 2023-03-24 19:43 -0700
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-24 20:01 -0700
Re: Boxed MCU with RS-232 Port Paul Rubin <no.email@nospam.invalid> - 2023-03-24 21:18 -0700
Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-03-24 15:35 -0700
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-24 18:21 -0700
Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-03-24 19:21 -0700
Re: Boxed MCU with RS-232 Port George Neuner <gneuner2@comcast.net> - 2023-03-25 21:42 -0400
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-25 19:26 -0700
Re: Boxed MCU with RS-232 Port Jim Jackson <jj@franjam.org.uk> - 2023-03-26 18:27 +0000
Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-03-26 13:23 -0700
Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-03-26 13:32 -0700
Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-03-26 13:52 -0700
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-26 19:30 -0700
Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-03-26 20:31 -0700
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-27 07:04 -0700
Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-03-27 09:21 -0700
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-27 09:56 -0700
Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-03-27 13:08 -0700
Re: Boxed MCU with RS-232 Port Jim Jackson <jj@franjam.org.uk> - 2023-03-27 20:46 +0000
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-27 15:07 -0700
Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-03-27 15:07 -0700
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-27 14:50 -0700
Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-03-27 15:07 -0700
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-27 15:24 -0700
Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-03-27 15:36 -0700
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-27 15:37 -0700
Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-03-27 15:42 -0700
Re: Boxed MCU with RS-232 Port David Brown <david.brown@hesbynett.no> - 2023-03-27 11:03 +0200
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-27 07:11 -0700
Re: Boxed MCU with RS-232 Port Dimiter_Popoff <dp@tgi-sci.com> - 2023-03-27 17:47 +0300
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-27 08:05 -0700
Re: Boxed MCU with RS-232 Port Dimiter_Popoff <dp@tgi-sci.com> - 2023-03-27 19:09 +0300
Re: Boxed MCU with RS-232 Port David Brown <david.brown@hesbynett.no> - 2023-03-27 17:38 +0200
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-26 19:22 -0700
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-26 19:11 -0700
Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-03-26 13:37 -0700
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-26 19:28 -0700
Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-03-27 13:38 -0700
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-27 15:05 -0700
Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-03-27 15:08 -0700
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-27 15:25 -0700
Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-03-27 15:38 -0700
Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-03-26 13:23 -0700
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-26 19:25 -0700
Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-03-26 20:31 -0700
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-27 07:05 -0700
Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-03-27 09:18 -0700
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-27 10:09 -0700
Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-03-27 12:16 -0700
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-27 13:03 -0700
Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-03-27 13:17 -0700
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-27 15:05 -0700
Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-03-27 15:40 -0700
Re: Boxed MCU with RS-232 Port Clifford Heath <no.spam@please.net> - 2023-03-28 10:36 +1100
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-27 17:59 -0700
Re: Boxed MCU with RS-232 Port Clifford Heath <no.spam@please.net> - 2023-03-28 12:58 +1100
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-27 20:41 -0700
Re: Boxed MCU with RS-232 Port Clifford Heath <no.spam@please.net> - 2023-03-28 15:21 +1100
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-28 08:37 -0700
Re: Boxed MCU with RS-232 Port Jim Jackson <jj@franjam.org.uk> - 2023-03-28 20:00 +0000
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-28 13:06 -0700
Re: Boxed MCU with RS-232 Port Clifford Heath <no.spam@please.net> - 2023-03-29 08:03 +1100
Re: Boxed MCU with RS-232 Port Don Y <blockedofcourse@foo.invalid> - 2023-03-28 00:11 -0700
Re: Boxed MCU with RS-232 Port "b...@gmx.com" <bl1@gmx.com> - 2023-03-27 16:17 -0700
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-27 18:12 -0700
Re: Boxed MCU with RS-232 Port Hans-Bernhard Bröker <HBBroeker@t-online.de> - 2023-03-24 19:26 +0100
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-24 08:03 -0700
Re: Boxed MCU with RS-232 Port Hans-Bernhard Bröker <HBBroeker@t-online.de> - 2023-03-24 19:10 +0100
Re: Boxed MCU with RS-232 Port Herbert Kleebauer <klee@unibwm.de> - 2023-03-24 17:16 +0100
Re: Boxed MCU with RS-232 Port Herbert Kleebauer <klee@unibwm.de> - 2023-03-24 18:54 +0100
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-24 11:34 -0700
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-27 10:18 -0700
Re: Boxed MCU with RS-232 Port Uwe Bonnes <bon@hertz.ikp.physik.tu-darmstadt.de> - 2023-03-28 20:53 +0000
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-28 16:12 -0700
Re: Boxed MCU with RS-232 Port Niklas Holsti <niklas.holsti@tidorum.invalid> - 2023-03-29 09:06 +0300
Re: Boxed MCU with RS-232 Port Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-29 00:44 -0700
Page 2 of 8 — ← Prev page 1 [2] 3 4 5 6 7 8 Next page →
| From | Andrew Smallshaw <andrews@sdf.org> |
|---|---|
| Date | 2023-01-18 12:15 +0000 |
| Message-ID | <slrntsfonr.9sa.andrews@sdf.org> |
| In reply to | #31551 |
On 2023-01-17, Rick C <gnuarm.deletethisbit@gmail.com> wrote: > On Tuesday, January 17, 2023 at 6:04:44 PM UTC-4, Paul Rubin wrote: >> Gack, yeah. I had been thinking, this isn't my area, but my >> understanding is that the RS232 electrical spec requires voltages that >> are somewhat above TTL logic levels, and that various crappy devices >> skimp on these voltages and mostly work anyway. So that is a thing to >> suspect if a home-brew RS232 device is acting flaky. It could be that >> the device at the other end expects those voltages to be closer to the >> real spec. > > They used a MAX3232CPE which generates it's own voltages using > switched capacitor voltage boost. I wanted to check the values of > the caps. Seems the have different minimum values depending on > the Vcc voltage. But they are not in the BoM. I'll ask about > this. It could easily be the cause of the problem. That was my first thought as well so I looked it up to double check. The MAX3232CPE is 0.1uF across the board so far as I can see. You do hit problems with MAX232's - the original needed 1uF caps but the MAX232A and several alternate manufacturers specify 0.1uF as a minimum. Problems can arise if a MAX232 is put in place of one of the alternatives but with the 3232 I'd expect people to get it right. OTOH the 3232 is a 3.3V compatible part. One thing they all have in common is the charge pumps are a bit weedy in terms of voltage, aiming for +/-5.5V regardless of supply voltage. That's within current specs but the RS232 minimum voltages have dropped over the years, I suppose it's possible the port of the receiver is an older design. In any case it doesn't leave particularly large headroom for losses. Do you know if the protocol translator is on a 3.3v or 5v supply? If the latter a MAX232A (note the A) is a drop-in replacement with typical +/-10V drive. If 3.3V a booster of some form will eliminate low voltage as an issue - in terms of off the shelf hardware that would probably be a pair of RS232<>RS422 line extenders back to back. -- Andrew Smallshaw andrews@sdf.org
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| From | Rick C <gnuarm.deletethisbit@gmail.com> |
|---|---|
| Date | 2023-01-18 04:55 -0800 |
| Message-ID | <4fa9560b-f1c6-4634-ab99-f9b1ae33531an@googlegroups.com> |
| In reply to | #31562 |
On Wednesday, January 18, 2023 at 8:16:01 AM UTC-4, Andrew Smallshaw wrote: > On 2023-01-17, Rick C <gnuarm.del...@gmail.com> wrote: > > On Tuesday, January 17, 2023 at 6:04:44 PM UTC-4, Paul Rubin wrote: > >> Gack, yeah. I had been thinking, this isn't my area, but my > >> understanding is that the RS232 electrical spec requires voltages that > >> are somewhat above TTL logic levels, and that various crappy devices > >> skimp on these voltages and mostly work anyway. So that is a thing to > >> suspect if a home-brew RS232 device is acting flaky. It could be that > >> the device at the other end expects those voltages to be closer to the > >> real spec. > > > > They used a MAX3232CPE which generates it's own voltages using > > switched capacitor voltage boost. I wanted to check the values of > > the caps. Seems the have different minimum values depending on > > the Vcc voltage. But they are not in the BoM. I'll ask about > > this. It could easily be the cause of the problem. > That was my first thought as well so I looked it up to double check. > The MAX3232CPE is 0.1uF across the board so far as I can see. You > do hit problems with MAX232's - the original needed 1uF caps but > the MAX232A and several alternate manufacturers specify 0.1uF as > a minimum. Problems can arise if a MAX232 is put in place of one > of the alternatives but with the 3232 I'd expect people to get it > right. The data sheet I saw has a table of minimum capacitance for three Vcc ranges, 3.3V, 5V and 3.3 to 5V approximately. Only 3.3V was 0.1 uF on all caps. The others were larger on at least one cap. Table 9-1 on page 12. > OTOH the 3232 is a 3.3V compatible part. One thing they all have > in common is the charge pumps are a bit weedy in terms of voltage, > aiming for +/-5.5V regardless of supply voltage. That's within > current specs but the RS232 minimum voltages have dropped over the > years, I suppose it's possible the port of the receiver is an > older design. You mean the RS-232 (TIA/EIAI) specification has changed? I have not seen this. > In any case it doesn't leave particularly large > headroom for losses. Do you know if the protocol translator is on > a 3.3v or 5v supply? If the latter a MAX232A (note the A) is a > drop-in replacement with typical +/-10V drive. If 3.3V a booster > of some form will eliminate low voltage as an issue - in terms of > off the shelf hardware that would probably be a pair of RS232<>RS422 > line extenders back to back. 5V supply. I don't know why you are talking about the MAX232. I've said "MAX3232CPE" several times. -- Rick C. -++ Get 1,000 miles of free Supercharging -++ Tesla referral code - https://ts.la/richard11209
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| From | Andrew Smallshaw <andrews@sdf.org> |
|---|---|
| Date | 2023-01-18 13:22 +0000 |
| Message-ID | <slrntsfsk6.hjt.andrews@sdf.org> |
| In reply to | #31564 |
On 2023-01-18, Rick C <gnuarm.deletethisbit@gmail.com> wrote: > > The data sheet I saw has a table of minimum capacitance for three > Vcc ranges, 3.3V, 5V and 3.3 to 5V approximately. Only 3.3V was > 0.1 uF on all caps. The others were larger on at least one cap. > Table 9-1 on page 12. 1 I'm reading Maxim's datasheet, see https://pdf1.alldatasheet.com/datasheet-pdf/view/73152/MAXIM/MAX3232CPE.html If you're looking at a sheet from another manufacturer that may change, leading to the same kind of incompatibility as seen with the MAX232 variants. > You mean the RS-232 (TIA/EIAI) specification has changed? I have > not seen this. Not recently but over time, yes. From memory the initial spec was +/-12V. I think it was RS232C that lowered it to +/-9V but don't hold me to that. It was either RS232E or F that lowered it again to +/-5V. Even the 'F' revision is fairly old now, but 'C' got so deeply ingrained it's not unusual to see references to RS232C even today. All specify inputs must tolerate up to +/-25V so there is cross-compatibility in terms of avoiding damage at least, but RS232 is one of those standards that often doesn't get implemented rigidly, e.g. power thieves, discrete implementations that are not strictly compliant, and so on. > 5V supply. I don't know why you are talking about the MAX232. > I've said "MAX3232CPE" several times. Acknowledged. MAX232 is the classic part for this application and where I suspect most people will have gained their initial experience. It's the one that has the most issue with the cap sizing. It's also a 5V only part. The MAX2323 is a 3.3V/5V part, at 5V it's interchangable with the MAX232 but the latter has higher output levels. If thresholds are the marginal factor here that's why I suggest it as a possible experiment. -- Andrew Smallshaw andrews@sdf.org
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| From | Andrew Smallshaw <andrews@sdf.org> |
|---|---|
| Date | 2023-01-18 13:28 +0000 |
| Message-ID | <slrntsfsva.hjt.andrews@sdf.org> |
| In reply to | #31565 |
On 2023-01-18, Andrew Smallshaw <andrews@sdf.org> wrote: > > Acknowledged. MAX232 is the classic part for this application and > where I suspect most people will have gained their initial experience. > It's the one that has the most issue with the cap sizing. It's > also a 5V only part. The MAX2323 is a 3.3V/5V part, at 5V it's > interchangable with the MAX232 but the latter has higher output > levels. If thresholds are the marginal factor here that's why I > suggest it as a possible experiment. Sorry, to emphasise again, a MAX232_A_ can be substituted. A genuine Maxim MAX232 needs larger caps. -- Andrew Smallshaw andrews@sdf.org
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| From | Rick C <gnuarm.deletethisbit@gmail.com> |
|---|---|
| Date | 2023-01-18 06:20 -0800 |
| Message-ID | <3901a35a-5517-45a4-b20d-c0bbcdf0e422n@googlegroups.com> |
| In reply to | #31565 |
On Wednesday, January 18, 2023 at 9:22:20 AM UTC-4, Andrew Smallshaw wrote: > On 2023-01-18, Rick C <gnuarm.del...@gmail.com> wrote: > > > > The data sheet I saw has a table of minimum capacitance for three > > Vcc ranges, 3.3V, 5V and 3.3 to 5V approximately. Only 3.3V was > > 0.1 uF on all caps. The others were larger on at least one cap. > > Table 9-1 on page 12. 1 > > I'm reading Maxim's datasheet, see > https://pdf1.alldatasheet.com/datasheet-pdf/view/73152/MAXIM/MAX3232CPE.html > If you're looking at a sheet from another manufacturer that may > change, leading to the same kind of incompatibility as seen with > the MAX232 variants. Did you look at the data sheet you linked to? What are the minimum capacitor recommendations for the MAX3232? > > You mean the RS-232 (TIA/EIAI) specification has changed? I have > > not seen this. > Not recently but over time, yes. From memory the initial spec was > +/-12V. I think it was RS232C that lowered it to +/-9V but don't > hold me to that. It was either RS232E or F that lowered it again > to +/-5V. Even the 'F' revision is fairly old now, but 'C' got so > deeply ingrained it's not unusual to see references to RS232C even > today. I think your memory is faulty. It has always been a minimum of ±5V at the driver output as long as I can recall. RS232C is from 1969. More recent changes were made to make the standard interworkable with ITU-T/CCITT V.24. The receiver voltage requirement of ±3V allows for variation in the actual threshold of the receiver. The spec has also always allowed up to ±25V at the driver, unloaded, and an output resistance of 3 to 7 kohms. The difference between the output and input voltage ranges allows for at least 2V of noise on the line. > All specify inputs must tolerate up to +/-25V so there is > cross-compatibility in terms of avoiding damage at least, but RS232 > is one of those standards that often doesn't get implemented rigidly, > e.g. power thieves, discrete implementations that are not strictly > compliant, and so on. > > 5V supply. I don't know why you are talking about the MAX232. > > I've said "MAX3232CPE" several times. > Acknowledged. MAX232 is the classic part for this application and > where I suspect most people will have gained their initial experience. > It's the one that has the most issue with the cap sizing. It's > also a 5V only part. The MAX2323 is a 3.3V/5V part, at 5V it's > interchangable with the MAX232 but the latter has higher output > levels. If thresholds are the marginal factor here that's why I > suggest it as a possible experiment. If the voltage levels are marginal, that would best be discovered by using an oscilloscope to measure them as well as the rise/fall times and the pulse timings. -- Rick C. +-- Get 1,000 miles of free Supercharging +-- Tesla referral code - https://ts.la/richard11209
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| From | David Brown <david.brown@hesbynett.no> |
|---|---|
| Date | 2023-01-18 10:04 +0100 |
| Message-ID | <tq8cmu$dr2m$3@dont-email.me> |
| In reply to | #31547 |
On 17/01/2023 21:19, Rick C wrote: > There's always more than meets the eye. I looked at the code and > although it's Arduino code, it is enough like C that I can tell it's > missing a few things. One is, the files I have are line delimited by > the DOS convention, /r/n. The program counts lines by checking for > /r, ignoring /n. I don't know if that would cause any problems, but > if the /r is missed from data corruption, the character buffer would > likely overflow, causing who knows what harm. The character count > should be checked for bounds. I'm not even sure why the data is > being buffered, it could be sent through one character at a time, > simply monitoring for the end of line. You mean "\r" and "\n" here - programming is fussy about the details! When counting line endings, I usually accept either character, and if "\r" is received then a following "\n" is ignored (and vice versa - some people get things wrong and send "\n\r"). The standard for DOS is "\r\n", the standard for *nix is "\n", and the standard for old Macs is "\r". I would not be happy simply counting "\r" characters unless I was sure the incoming data always used carriage returns - if I were to pick just one character, it would be "\n". But checking for either is best. Data corruption is always something you have to consider. Sometimes you can't do much about it, and will just pass on the mess - or skip it until the data looks good again. But you at least want to make sure there are no buffer overflows if a line ending is missed!
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| From | Theo <theom+news@chiark.greenend.org.uk> |
|---|---|
| Date | 2023-01-18 16:18 +0000 |
| Message-ID | <HJl*VBG8y@news.chiark.greenend.org.uk> |
| In reply to | #31541 |
Rick C <gnuarm.deletethisbit@gmail.com> wrote: > Anyone know of such a box? The programming might be contracted out, if > you are interested. There's a prototype using an Arduino nano, but some > of them are flaky and it would not hurt to start over from scratch. I was wondering about boxes that do MIDI, eg MIDI to USB conversion. MIDI is just serial with a strange (31K) baud rate, and those boxes often have multiple MIDI ports (although not as many UARTs as ports). The downside is that MIDI is a current loop so the electrical signalling is wrong. Also wondered if there are RS232-to-X boxes (eg USB) where the main chip is an MCU that can be reprogrammed. But if you want two ports that's harder. Another thought is to find a common 'gender changer' case, a plastic case that would take a DB9 connector at each end, and drop in your own PCB. eg https://uk.misumi-ec.com/vona2/detail/222301880534/# - they have a DB9 to DB9 version: https://uk.misumi-ec.com/pdf/vona/el/PVT1/PVT1_670909M_Datasheet_de_en_1.pdf (this used to be a very common design but seems harder to find these days) Theo
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| From | Paul Rubin <no.email@nospam.invalid> |
|---|---|
| Date | 2023-01-18 14:10 -0800 |
| Message-ID | <87ilh3try3.fsf@nightsong.com> |
| In reply to | #31568 |
Theo <theom+news@chiark.greenend.org.uk> writes: > Another thought is to find a common 'gender changer' case, a plastic case > that would take a DB9 connector at each end, and drop in your own PCB. eg I think the hope is to not build hardware at all, including dropping boards into things, but instead to buy a complete and packaged box that you can plug cables into. I'm surprised that it seems this difficult. Maybe it is an opportunity.
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| From | Theo <theom+news@chiark.greenend.org.uk> |
|---|---|
| Date | 2023-01-19 10:29 +0000 |
| Message-ID | <GJl*KBK8y@news.chiark.greenend.org.uk> |
| In reply to | #31569 |
Paul Rubin <no.email@nospam.invalid> wrote: > Theo <theom+news@chiark.greenend.org.uk> writes: > > Another thought is to find a common 'gender changer' case, a plastic case > > that would take a DB9 connector at each end, and drop in your own PCB. eg > > I think the hope is to not build hardware at all, including dropping > boards into things, but instead to buy a complete and packaged box that > you can plug cables into. I'm surprised that it seems this difficult. > Maybe it is an opportunity. I know, but I don't think there are better options. I'm not really surprised, because the existence of a piece of hardware depends on a pre-existing market for that hardware. The market for RS232-to-X is well established, for various X. But RS232 to RS232 seems less likely, because it's not clear what people would use it for. The secondary question is, if a thing of the right shape exists, whether it can be reprogrammed. That is more common in an RS232-to-X product where some protocol conversion is involved, but often those are fixed-function chips (eg RS232 to USB). Even if it is reprogrammable, it may be 'unofficially', in which case you're maybe in a lifetime buy situation in case they change the MCU or something that would mean your reprogramming strategy no longer works. In the latter case I'd hunt around Alibaba looking for things of the right shape, but I think you'd first need to establish a use case that you can search for. Without that, it's just a 'box with MCU and two serial ports' and why would somebody want that? The alternative is to go for something highly overspecced that just happens to have two serial ports. A PC is an obvious one: https://www.alibaba.com/product-detail/Factory-Wholesale-Price-Dual-Band-Soft_1600482484162.html? or else there are dual RS232 to Modbus/RS485 converters: https://www.alibaba.com/product-detail/USR-N520-H7-Version-Dual-Port_60593907847.html and maybe you could reprogram those (it claims an ST Cortex M7). But it's pot luck whether the next batch will have a different CPU - the listing says they already revved it from a TI Cortex M4. Theo
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| From | Don Y <blockedofcourse@foo.invalid> |
|---|---|
| Date | 2023-01-19 05:41 -0700 |
| Message-ID | <tqbdpi$1hugc$1@dont-email.me> |
| In reply to | #31572 |
On 1/19/2023 3:29 AM, Theo wrote: > I'm not really surprised, because the existence of a piece of hardware > depends on a pre-existing market for that hardware. The market for > RS232-to-X is well established, for various X. But RS232 to RS232 seems > less likely, because it's not clear what people would use it for. > > The secondary question is, if a thing of the right shape exists, whether it > can be reprogrammed. That is more common in an RS232-to-X product where > some protocol conversion is involved, but often those are fixed-function > chips (eg RS232 to USB). Even if it is reprogrammable, it may be > 'unofficially', in which case you're maybe in a lifetime buy situation in > case they change the MCU or something that would mean your reprogramming > strategy no longer works. > > In the latter case I'd hunt around Alibaba looking for things of the right > shape, but I think you'd first need to establish a use case that you can > search for. Without that, it's just a 'box with MCU and two serial ports' > and why would somebody want that? > > The alternative is to go for something highly overspecced that just happens > to have two serial ports. A PC is an obvious one: > https://www.alibaba.com/product-detail/Factory-Wholesale-Price-Dual-Band-Soft_1600482484162.html? > > or else there are dual RS232 to Modbus/RS485 converters: > https://www.alibaba.com/product-detail/USR-N520-H7-Version-Dual-Port_60593907847.html > and maybe you could reprogram those (it claims an ST Cortex M7). > But it's pot luck whether the next batch will have a different CPU - the > listing says they already revved it from a TI Cortex M4. Two-port terminal server -- with a single PC to service as many as necessary. No changes to the TS. If the TS is redesigned, the i/f (to the network) will remain the same (excepting, possibly, configuration options if not autobaud). SW resides in the PC -- and can snoop/log/replace/remote the data if ever necessary without upgrading "firmware" in a device. Secure comms to/from the PC so it's AS IF it was hidden in firmware. Costly, though. And, adds the need for a PC (which can likely be shared). But, easy-peasy to implement! As you said, unless there is an existing market, who's going to bother designing it?
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| From | Rick C <gnuarm.deletethisbit@gmail.com> |
|---|---|
| Date | 2023-01-19 10:00 -0800 |
| Message-ID | <3ca2a6ac-7d53-4e6a-808b-515e02e56c79n@googlegroups.com> |
| In reply to | #31573 |
On Thursday, January 19, 2023 at 7:41:28 AM UTC-5, Don Y wrote: > On 1/19/2023 3:29 AM, Theo wrote: > > I'm not really surprised, because the existence of a piece of hardware > > depends on a pre-existing market for that hardware. The market for > > RS232-to-X is well established, for various X. But RS232 to RS232 seems > > less likely, because it's not clear what people would use it for. > > > > The secondary question is, if a thing of the right shape exists, whether it > > can be reprogrammed. That is more common in an RS232-to-X product where > > some protocol conversion is involved, but often those are fixed-function > > chips (eg RS232 to USB). Even if it is reprogrammable, it may be > > 'unofficially', in which case you're maybe in a lifetime buy situation in > > case they change the MCU or something that would mean your reprogramming > > strategy no longer works. > > > > In the latter case I'd hunt around Alibaba looking for things of the right > > shape, but I think you'd first need to establish a use case that you can > > search for. Without that, it's just a 'box with MCU and two serial ports' > > and why would somebody want that? > > > > The alternative is to go for something highly overspecced that just happens > > to have two serial ports. A PC is an obvious one: > > https://www.alibaba.com/product-detail/Factory-Wholesale-Price-Dual-Band-Soft_1600482484162.html? > > > > or else there are dual RS232 to Modbus/RS485 converters: > > https://www.alibaba.com/product-detail/USR-N520-H7-Version-Dual-Port_60593907847.html > > and maybe you could reprogram those (it claims an ST Cortex M7). > > But it's pot luck whether the next batch will have a different CPU - the > > listing says they already revved it from a TI Cortex M4. > Two-port terminal server -- with a single PC to service as many as necessary. > No changes to the TS. If the TS is redesigned, the i/f (to the network) > will remain the same (excepting, possibly, configuration options if not > autobaud). SW resides in the PC -- and can snoop/log/replace/remote the > data if ever necessary without upgrading "firmware" in a device. Secure > comms to/from the PC so it's AS IF it was hidden in firmware. > > Costly, though. And, adds the need for a PC (which can likely be shared). > But, easy-peasy to implement! If you add a PC, there's no need for the terminal server. There's also no need for about half the equipment in this system. But thanks for the thought. > As you said, unless there is an existing market, who's going to bother > designing it? There are many, many devices that you can program. They are just more complex than required. There are many, many devices that are MCUs with dual RS232 ports, just just don't come in boxes. It's silly to think there is *no* market for a controller with two serial ports, in an enclosure. We just haven't found the devices. Thanks for the suggestions. -- Rick C. ++- Get 1,000 miles of free Supercharging ++- Tesla referral code - https://ts.la/richard11209
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| From | Paul Rubin <no.email@nospam.invalid> |
|---|---|
| Date | 2023-01-19 12:42 -0800 |
| Message-ID | <87wn5is1bv.fsf@nightsong.com> |
| In reply to | #31575 |
Rick C <gnuarm.deletethisbit@gmail.com> writes: > There are many, many devices that are MCUs with dual RS232 ports, just > just don't come in boxes. It's really weird that there are many catalogs and databases of small computer products for sale. Some of them are board level products and some are boxed products. But there seems to be no obvious way to select just the boxed products. Packaged small computers certainly exist. This one is overkill, but considerably less so than a full-blown Linux box. It just doesn't have RS232: https://www.seeedstudio.com/Wio-Terminal-p-4509.html Could something with a USB host port that you can plug an FTDI cable be ok? Lol, all this needs is DB9's: https://www.tindie.com/products/tindiescx/sc131-pocket-sized-z180-romwbw-cpm-computer-kit/ Actually it doesn't say whether the serial ports have RS232 voltages, so maybe not. Given the willingness to pay $100 per unit in 10+ quantity, maybe it is easiest to get something built out of existing boards and enclosures.
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| From | Rick C <gnuarm.deletethisbit@gmail.com> |
|---|---|
| Date | 2023-01-19 14:10 -0800 |
| Message-ID | <55d74085-4a5e-48e5-99a3-ac751876c083n@googlegroups.com> |
| In reply to | #31579 |
On Thursday, January 19, 2023 at 3:42:53 PM UTC-5, Paul Rubin wrote: > Rick C <gnuarm.del...@gmail.com> writes: > > There are many, many devices that are MCUs with dual RS232 ports, just > > just don't come in boxes. > It's really weird that there are many catalogs and databases of small > computer products for sale. Some of them are board level products and > some are boxed products. But there seems to be no obvious way to select > just the boxed products. > > Packaged small computers certainly exist. This one is overkill, but > considerably less so than a full-blown Linux box. It just doesn't have > RS232: > > https://www.seeedstudio.com/Wio-Terminal-p-4509.html > > Could something with a USB host port that you can plug an FTDI cable be > ok? The "box" is a bit consumer oriented. This is going in a water treatment facility. The rest of the system is a plexiglass tank with running water and fish, a commercial PLC/EDAS unit and a many thousand dollar water sensor. This is why I would like to change the device from what is essentially a home made, 3D printed device. In this device is an Arduino nano, affixed to a purpose built, perfboard RS-232 converter. So a shiny plastic, LCD adorned case with no screwdowns, requiring USB dongles, is not what I'm looking for. > Lol, all this needs is DB9's: > > https://www.tindie.com/products/tindiescx/sc131-pocket-sized-z180-romwbw-cpm-computer-kit/ > > Actually it doesn't say whether the serial ports have RS232 voltages, so > maybe not. No, it says 5V. 2 x Serial ports, asynchronous, 5-volt, with software selectable baud rates. > Given the willingness to pay $100 per unit in 10+ quantity, maybe it is > easiest to get something built out of existing boards and enclosures. Maybe. Thanks for your comments. Interesting that you found these, which I couldn't do. -- Rick C. ---+ Get 1,000 miles of free Supercharging ---+ Tesla referral code - https://ts.la/richard11209
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| From | Paul Rubin <no.email@nospam.invalid> |
|---|---|
| Date | 2023-01-19 16:16 -0800 |
| Message-ID | <87sfg6rrgd.fsf@nightsong.com> |
| In reply to | #31581 |
Rick C <gnuarm.deletethisbit@gmail.com> writes: > In this device is an Arduino nano, affixed to a purpose built, > perfboard RS-232 converter.... So a shiny plastic, LCD adorned case > with no screwdowns, requiring USB dongles, is not what I'm looking > for. Ah, I see. Hmm, home-made RS232 converter on perfboard, yeah, that sounds like trouble. Maybe use a full sized Arduino (Uno or Leonardo) and an RS232 shield? https://wiki.dfrobot.com/RS232_Shield just plugs into the headers on the bigger Arduino boards. I don't know whether you can stack two of them. If you used a dongle with a cable, that whole thing could go inside an enclosure with panel mounted connectors, assuming no serious size constraints on the box. Maybe you could recycle the enclosure from a thing like this, rather than 3d printing: https://www.cableleader.com/2-way-db9-manual-data-switch-ab-male.html
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| From | Grant Edwards <invalid@invalid.invalid> |
|---|---|
| Date | 2023-01-19 16:07 +0000 |
| Message-ID | <tqbprt$cmk$1@reader2.panix.com> |
| In reply to | #31572 |
On 2023-01-19, Theo <theom+news@chiark.greenend.org.uk> wrote: > I'm not really surprised, because the existence of a piece of hardware > depends on a pre-existing market for that hardware. The market for > RS232-to-X is well established, for various X. But RS232 to RS232 seems > less likely, because it's not clear what people would use it for. The company I work for used to sell a small industrial "shoebox" PC with 8 serial ports (232/422/485 software selectable) and a small SSD. It had some slow Intel processor and ran Windows 7 or Linux. It never came close to breaking even, and was carried mainly as a convenience for customers who purchased a particular large and profitable software product (that used serial ports) and they didn't want to configure their own machines. 15 years ago it made sense, but these days, everybody runs the software product on a VM and uses Ethernet->serial interfaces for the serial ports. The supplier stopped making the shoebox machines, and nobody had bought any for a couple years -- so we never bothered to find a replacement. We also used to sell a family of small boxes with ARM CPUs, a bunch of serial ports, and an RTOS-based software development kit. The cost of supporting the SDK was way too high to justify for the meager sales to customers who wanted to write their own firmware, so the SDK was discontinued. [The boxes themselves are still sold running propritary firmware for varioius applications.]
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| From | Rick C <gnuarm.deletethisbit@gmail.com> |
|---|---|
| Date | 2023-01-19 10:13 -0800 |
| Message-ID | <0c5187ff-d06e-44d2-9788-80eb2bd3afe9n@googlegroups.com> |
| In reply to | #31574 |
On Thursday, January 19, 2023 at 11:07:30 AM UTC-5, Grant Edwards wrote: > On 2023-01-19, Theo <theom...@chiark.greenend.org.uk> wrote: > > > I'm not really surprised, because the existence of a piece of hardware > > depends on a pre-existing market for that hardware. The market for > > RS232-to-X is well established, for various X. But RS232 to RS232 seems > > less likely, because it's not clear what people would use it for. > The company I work for used to sell a small industrial "shoebox" PC > with 8 serial ports (232/422/485 software selectable) and a small > SSD. It had some slow Intel processor and ran Windows 7 or Linux. > > It never came close to breaking even, and was carried mainly as a > convenience for customers who purchased a particular large and > profitable software product (that used serial ports) and they didn't > want to configure their own machines. 15 years ago it made sense, but > these days, everybody runs the software product on a VM and uses > Ethernet->serial interfaces for the serial ports. > > The supplier stopped making the shoebox machines, and nobody had > bought any for a couple years -- so we never bothered to find a > replacement. > > We also used to sell a family of small boxes with ARM CPUs, a bunch of > serial ports, and an RTOS-based software development kit. The cost of > supporting the SDK was way too high to justify for the meager sales to > customers who wanted to write their own firmware, so the SDK was > discontinued. [The boxes themselves are still sold running propritary > firmware for varioius applications.] Yeah, this is still far above what this project requires, an Arduino nano and some 100 lines of custom code. As soon as you say RTOS or any OS, it has become a NASA moon shot compared to what is required. That's what is surprising me. I would have expected something along the lines of a very low end PLC. But they just don't exist really. Even if your company could not make any money on them, there are companies that sell very large quantities of products I expect. Strange. -- Rick C. ---- Get 1,000 miles of free Supercharging ---- Tesla referral code - https://ts.la/richard11209
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| From | Don Y <blockedofcourse@foo.invalid> |
|---|---|
| Date | 2023-01-19 14:51 -0700 |
| Message-ID | <tqce0c$1ncog$1@dont-email.me> |
| In reply to | #31574 |
On 1/19/2023 9:07 AM, Grant Edwards wrote: > It never came close to breaking even, and was carried mainly as a > convenience for customers who purchased a particular large and > profitable software product (that used serial ports) and they didn't > want to configure their own machines. 15 years ago it made sense, but > these days, everybody runs the software product on a VM and uses > Ethernet->serial interfaces for the serial ports. Exactly. A PC is typically limited in terms of how many ports it can support -- regardless of the aggregate data rate. OTOH, you can open a socket per "virtual serial port" and handle scores of low data rate transactions in one appliance. And, your PC can be on the other side of the continent! [I like the single port terminal servers to talk with my legacy peripherals, here. Also has the advantage that *any* PC can connect to them instead of being hardwired to *a* machine with *a* serial port!] It's only a matter of time before we see everything with a network interface (wired *or* wireless). All these other efforts will just be seen as distractions -- effort wasted pursuing half-assed solutions.
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| From | Rick C <gnuarm.deletethisbit@gmail.com> |
|---|---|
| Date | 2023-01-19 10:06 -0800 |
| Message-ID | <3fbec746-63e2-4f82-8fc8-e8179936b49bn@googlegroups.com> |
| In reply to | #31572 |
On Thursday, January 19, 2023 at 5:29:44 AM UTC-5, Theo wrote: > Paul Rubin <no.e...@nospam.invalid> wrote: > > Theo <theom...@chiark.greenend.org.uk> writes: > > > Another thought is to find a common 'gender changer' case, a plastic case > > > that would take a DB9 connector at each end, and drop in your own PCB. eg > > > > I think the hope is to not build hardware at all, including dropping > > boards into things, but instead to buy a complete and packaged box that > > you can plug cables into. I'm surprised that it seems this difficult. > > Maybe it is an opportunity. > I know, but I don't think there are better options. > > I'm not really surprised, because the existence of a piece of hardware > depends on a pre-existing market for that hardware. The market for > RS232-to-X is well established, for various X. But RS232 to RS232 seems > less likely, because it's not clear what people would use it for. You aren't making sense. There are literally hundreds if not thousands of boxes with two serial ports. Some have only that. Others have extra ports. But none are programmable. There are lots of programmable controllers with dual serial ports, but not in an enclosure. Not sure what you are trying to say. But it's not important, because it's not an advancement toward a solution. > The secondary question is, if a thing of the right shape exists, whether it > can be reprogrammed. That is more common in an RS232-to-X product where > some protocol conversion is involved, but often those are fixed-function > chips (eg RS232 to USB). Even if it is reprogrammable, it may be > 'unofficially', in which case you're maybe in a lifetime buy situation in > case they change the MCU or something that would mean your reprogramming > strategy no longer works. > > In the latter case I'd hunt around Alibaba looking for things of the right > shape, but I think you'd first need to establish a use case that you can > search for. Without that, it's just a 'box with MCU and two serial ports' > and why would somebody want that? Alibaba is literally the last place I would by something like this, for all the obvious reasons, including the risk of never seeing the product or your money again. > The alternative is to go for something highly overspecced that just happens > to have two serial ports. A PC is an obvious one: > https://www.alibaba.com/product-detail/Factory-Wholesale-Price-Dual-Band-Soft_1600482484162.html? > > or else there are dual RS232 to Modbus/RS485 converters: > https://www.alibaba.com/product-detail/USR-N520-H7-Version-Dual-Port_60593907847.html > and maybe you could reprogram those (it claims an ST Cortex M7). > But it's pot luck whether the next batch will have a different CPU - the > listing says they already revved it from a TI Cortex M4. None of these devices are programmable and... they are from Alibaba. I'm trying to remember, who was Alibaba associated with? Oh yeah, forty thieves! -- Rick C. +++ Get 1,000 miles of free Supercharging +++ Tesla referral code - https://ts.la/richard11209
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| From | Theo <theom+news@chiark.greenend.org.uk> |
|---|---|
| Date | 2023-01-20 13:03 +0000 |
| Message-ID | <IJl*grQ8y@news.chiark.greenend.org.uk> |
| In reply to | #31576 |
Rick C <gnuarm.deletethisbit@gmail.com> wrote: > On Thursday, January 19, 2023 at 5:29:44 AM UTC-5, Theo wrote: > > Paul Rubin <no.e...@nospam.invalid> wrote: > > > Theo <theom...@chiark.greenend.org.uk> writes: > > > > Another thought is to find a common 'gender changer' case, a plastic case > > > > that would take a DB9 connector at each end, and drop in your own PCB. eg > > > > > > I think the hope is to not build hardware at all, including dropping > > > boards into things, but instead to buy a complete and packaged box that > > > you can plug cables into. I'm surprised that it seems this difficult. > > > Maybe it is an opportunity. > > I know, but I don't think there are better options. > > > > I'm not really surprised, because the existence of a piece of hardware > > depends on a pre-existing market for that hardware. The market for > > RS232-to-X is well established, for various X. But RS232 to RS232 seems > > less likely, because it's not clear what people would use it for. > > You aren't making sense. There are literally hundreds if not thousands of > boxes with two serial ports. Some have only that. Others have extra > ports. But none are programmable. There are lots of programmable > controllers with dual serial ports, but not in an enclosure. Not sure > what you are trying to say. But it's not important, because it's not an > advancement toward a solution. You indicated you wanted RS232-to-RS232, with no extra stuff. Not hardwired, not a PC, not a pile of dongles plugged into another thing. Show me the boxes that do that. You can of course find boxes that happen to have two serial ports as well as (lots of) other stuff. But they're designed to do some other 'X' (eg Modbus), and aren't (officially) reprogrammable. What is the use case for a programmable RS232-to-RS232 product? If you can think of a use case, maybe you can find somebody who makes such a thing. > Alibaba is literally the last place I would by something like this, for > all the obvious reasons, including the risk of never seeing the product or > your money again. Alibaba is a good place to answer the question 'if you can think of it, does it exist?'. I would not buy them from there. But, for example, it turned up the dual RS232 to Modbus converters. Once knowing that as a possible market I might then go and see if there was a sensible supplier of that. Searching Alibaba did not come up with examples of boxes doing RS232 to RS232, which suggests that specifically is a market that doesn't really exist. A PLC is one starting point - maybe there's a dual RS232 PLC out there. Alibaba shows various RS232 PLCs - maybe something like that would suffice (from a local supplier)? Theo
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| From | Rick C <gnuarm.deletethisbit@gmail.com> |
|---|---|
| Date | 2023-01-20 06:28 -0800 |
| Message-ID | <77e7774c-f7bd-4bbc-ae62-f5ee0aaf0bedn@googlegroups.com> |
| In reply to | #31585 |
On Friday, January 20, 2023 at 8:03:30 AM UTC-5, Theo wrote: > Rick C <gnuarm.del...@gmail.com> wrote: > > On Thursday, January 19, 2023 at 5:29:44 AM UTC-5, Theo wrote: > > > Paul Rubin <no.e...@nospam.invalid> wrote: > > > > Theo <theom...@chiark.greenend.org.uk> writes: > > > > > Another thought is to find a common 'gender changer' case, a plastic case > > > > > that would take a DB9 connector at each end, and drop in your own PCB. eg > > > > > > > > I think the hope is to not build hardware at all, including dropping > > > > boards into things, but instead to buy a complete and packaged box that > > > > you can plug cables into. I'm surprised that it seems this difficult. > > > > Maybe it is an opportunity. > > > I know, but I don't think there are better options. > > > > > > I'm not really surprised, because the existence of a piece of hardware > > > depends on a pre-existing market for that hardware. The market for > > > RS232-to-X is well established, for various X. But RS232 to RS232 seems > > > less likely, because it's not clear what people would use it for. > > > > You aren't making sense. There are literally hundreds if not thousands of > > boxes with two serial ports. Some have only that. Others have extra > > ports. But none are programmable. There are lots of programmable > > controllers with dual serial ports, but not in an enclosure. Not sure > > what you are trying to say. But it's not important, because it's not an > > advancement toward a solution. > You indicated you wanted RS232-to-RS232, with no extra stuff. Not > hardwired, not a PC, not a pile of dongles plugged into another thing. > Show me the boxes that do that. I didn't say no "extra stuff". If it has other I/O, that's ok, just not excessive. A full blown PC has the problem that it is not easily rebooted, much larger than an MCU based device and sucks power. Here are some devices that would be perfectly suitable if they were programmable. https://www.brainboxes.com/product/usb-to-serial/usb/us-257 https://www.brainboxes.com/product/ethernet-to-serial/db9/es-257 > You can of course find boxes that happen to have two serial ports as well as > (lots of) other stuff. But they're designed to do some other 'X' (eg > Modbus), and aren't (officially) reprogrammable. Yes, that's the problem. > What is the use case for a programmable RS232-to-RS232 product? Who cares? You seem just be interested in an argument. What's the use case for any programmable device? This application is a perfect example. > If you can think of a use case, maybe you can find somebody who makes such a > thing. If it has serial ports and is programmable, it would not be sold for a specific use case. The industrial computers or PLC devices are not sold for a specific use case. > > Alibaba is literally the last place I would by something like this, for > > all the obvious reasons, including the risk of never seeing the product or > > your money again. > Alibaba is a good place to answer the question 'if you can think of it, does > it exist?'. I would not buy them from there. But, for example, it turned > up the dual RS232 to Modbus converters. Once knowing that as a possible > market I might then go and see if there was a sensible supplier of that. Perhaps you could explain what Modbus is and how it is related to this? Would such a converter be programmable? > Searching Alibaba did not come up with examples of boxes doing RS232 to > RS232, which suggests that specifically is a market that doesn't really > exist. Still hung up on "markets", eh? > A PLC is one starting point - maybe there's a dual RS232 PLC out there. > Alibaba shows various RS232 PLCs - maybe something like that would suffice > (from a local supplier)? Perhaps, but I haven't found one with any RS232, other than as attached modules and that always raises the price far too much. Even the PLC is too expensive, being some hundreds of dollars, rather than the lower end price I'm looking for. Thanks for your comments. -- Rick C. --++ Get 1,000 miles of free Supercharging --++ Tesla referral code - https://ts.la/richard11209
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