Rick C <gnuarm.deletethisbit@gmail.com> writes:
>> More seriously, the thing that fails the most on Rpi-style boards is
>> the SD card.
> So potentially lose an entire day of data? LOL

Does that refer to the SD card failing? I didn't realize you were
envisioning saving any data on the Pi. If you were using a RPi type of
board presumably you'd upload incoming data (maybe over a network) as it
arrived. But that is far away from the Arduino approach.

> Yes, and I would still need to worry about it being stepped on by a
> dinosaur.

Ok, so it sounds like you are confident that something is really wrong
with the Arduino boxes that are failing. Seems reasonable.

On Wednesday, January 18, 2023 at 6:19:16 PM UTC-4, Paul Rubin wrote:
> Rick C <gnuarm.del...@gmail.com> writes:
> >> More seriously, the thing that fails the most on Rpi-style boards is
> >> the SD card.
> > So potentially lose an entire day of data? LOL
> Does that refer to the SD card failing? I didn't realize you were
> envisioning saving any data on the Pi. If you were using a RPi type of
> board presumably you'd upload incoming data (maybe over a network) as it
> arrived. But that is far away from the Arduino approach.
> > Yes, and I would still need to worry about it being stepped on by a
> > dinosaur.
> Ok, so it sounds like you are confident that something is really wrong
> with the Arduino boxes that are failing. Seems reasonable.

I don't think we are communicating at all. When the glitch happens, no further data is sent to the recipient, until the translator is reset. At this point, you have some idea in your mind as to what has been designed, that seems to not match reality. Sorry if I've misled you.

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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

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?

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.]

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.

--

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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.

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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
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Rick C <gnuarm.deletethisbit@gmail.com> writes:
> When the glitch happens, no further data is sent to the recipient,
> until the translator is reset. At this point, you have some idea in
> your mind as to what has been designed, that seems to not match
> reality.

I think I understand what has been designed. What I don't have is any
solid idea of what is going wrong. I therefore can't infer that the
mysterious problem won't also affect other hardware. If you're not
worried about that, then fine. Your judgment is better than mine when
it comes to stuff like that.

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.

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.

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.
--

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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

Il 17/01/2023 16:24, Rick C ha scritto:
> The unit only really needs one serial port, but it is more convenient to have two connectors, so I guess it needs to ports. One port will only receive and the other only transmit, no handshaking.
>
> The function is pretty simple. A sensor sends a line of about 50 chars, at 9,600 bps, once per second. This box counts 20 lines and adds a header. So nothing fancy is required of the MCU. There are parameters set when starting operation.
>
> The main thing I'm having trouble finding, is this needs to be in a box as a unit, not a board and a box to be assembled. Google hasn't been much help returning all sorts of things that aren't useful.
>
> 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 don't know if the following ideas were already suggested by others in
this long thread.

First idea is to make your own box. I know you asked for a ready-to-use
box, but for low-medium quantities and for not extremely low-cost
applications, IMHO making a custom box is not so difficult. There are
many many plastic or metallic enclosures amopng you can choose.
Pick one of your favorite MCU EVB with expansion connector (even an
Arduino with two UARTs), and pick two UART/RS232 converters on PCB (such
as [1]). Put them in the box.
Of course you need to make some holes or apertures in the panels and
assemble some cablings.

The second idea is to use one off-the-shelf box with a host USB port
(based on Linux, such as Raspberry, or a simple MCU with a host USB).
Now you only need a two-ports USB hub and a couple of USB/RS232
converter. Of course this isn't a box, because the USB/RS232 converters
are cables, but as usual you can put them in a custom box.

[2] https://www.digikey.it/short/nqf0tc78

On Friday, January 20, 2023 at 2:54:21 AM UTC-5, pozz wrote:
> Il 17/01/2023 16:24, Rick C ha scritto:
> > The unit only really needs one serial port, but it is more convenient to have two connectors, so I guess it needs to ports. One port will only receive and the other only transmit, no handshaking.
> >
> > The function is pretty simple. A sensor sends a line of about 50 chars, at 9,600 bps, once per second. This box counts 20 lines and adds a header. So nothing fancy is required of the MCU. There are parameters set when starting operation.
> >
> > The main thing I'm having trouble finding, is this needs to be in a box as a unit, not a board and a box to be assembled. Google hasn't been much help returning all sorts of things that aren't useful.
> >
> > 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 don't know if the following ideas were already suggested by others in
> this long thread.
>
> First idea is to make your own box. I know you asked for a ready-to-use
> box, but for low-medium quantities and for not extremely low-cost
> applications, IMHO making a custom box is not so difficult. There are
> many many plastic or metallic enclosures amopng you can choose.
> Pick one of your favorite MCU EVB with expansion connector (even an
> Arduino with two UARTs), and pick two UART/RS232 converters on PCB (such
> as [1]). Put them in the box.
> Of course you need to make some holes or apertures in the panels and
> assemble some cablings.
>
> The second idea is to use one off-the-shelf box with a host USB port
> (based on Linux, such as Raspberry, or a simple MCU with a host USB).
> Now you only need a two-ports USB hub and a couple of USB/RS232
> converter. Of course this isn't a box, because the USB/RS232 converters
> are cables, but as usual you can put them in a custom box.
>
>
> [2] https://www.digikey.it/short/nqf0tc78

Thanks for your suggestion.

--

Rick C.

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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

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

On 19.01.2023 19:06, Rick C wrote:

> 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.

Seems you are 25 years to late. But this company is still selling
its device (with a Z180 processor). Seems this is what you are
asking for (but maybe without the price):

https://www.kksystems.com/programmable-protocol-converters/ppc-4-h2-c.html/
https://www.kksystems.com/datasheets/pdf_files/ppclft.pdf
https://www.kksystems.com/datasheets/pdf_files/ppcman.pdf

> Alibaba is literally the last place I would by something like
> this, for all the obvious reasons, including the risk of never
> Yseeing the product or your money again.

I bought many things from Aliexpress an nearly never had
any problems.

On Friday, January 20, 2023 at 1:17:59 PM UTC-5, Herbert Kleebauer wrote:
> On 19.01.2023 19:06, Rick C wrote:
>
>
> > 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.
> Seems you are 25 years to late. But this company is still selling
> its device (with a Z180 processor). Seems this is what you are
> asking for (but maybe without the price):
>
> https://www.kksystems.com/programmable-protocol-converters/ppc-4-h2-c.html/
> https://www.kksystems.com/datasheets/pdf_files/ppclft.pdf
> https://www.kksystems.com/datasheets/pdf_files/ppcman.pdf
> > Alibaba is literally the last place I would by something like
> > this, for all the obvious reasons, including the risk of never
> > Yseeing the product or your money again.
>
> I bought many things from Aliexpress an nearly never had
> any problems.

I'm pleased for you. People safely cross streets outside the crosswalk, yet people are killed doing that every day. Do you tell your kids it's a good thing to do?

--

Rick C.

-+-- Get 1,000 miles of free Supercharging
-+-- Tesla referral code - https://ts.la/richard11209

On 1/20/2023 22:37, Rick C wrote:
> On Friday, January 20, 2023 at 1:17:59 PM UTC-5, Herbert Kleebauer wrote:
>> On 19.01.2023 19:06, Rick C wrote:
>>
>>
>>> 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.
>> Seems you are 25 years to late. But this company is still selling
>> its device (with a Z180 processor). Seems this is what you are
>> asking for (but maybe without the price):
>>
>> https://www.kksystems.com/programmable-protocol-converters/ppc-4-h2-c.html/
>> https://www.kksystems.com/datasheets/pdf_files/ppclft.pdf
>> https://www.kksystems.com/datasheets/pdf_files/ppcman.pdf
>>> Alibaba is literally the last place I would by something like
>>> this, for all the obvious reasons, including the risk of never
>>> Yseeing the product or your money again.
>>
>> I bought many things from Aliexpress an nearly never had
>> any problems.
>
> I'm pleased for you. People safely cross streets outside the crosswalk, yet people are killed doing that every day. Do you tell your kids it's a good thing to do?
>

Buying a $10 or a $100 thing at aliexpress is not that similar
to getting killed, you know.
I have bought a lot of small stuff there and have not yet been killed.
Oh yes, and I do cross streets as I please and I am still alive, but
that's not a very similar matter, as explained above.

On Friday, January 20, 2023 at 4:02:27 PM UTC-5, Dimiter wrote:
> On 1/20/2023 22:37, Rick C wrote:
> > On Friday, January 20, 2023 at 1:17:59 PM UTC-5, Herbert Kleebauer wrote:
> >> On 19.01.2023 19:06, Rick C wrote:
> >>
> >>
> >>> 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.
> >> Seems you are 25 years to late. But this company is still selling
> >> its device (with a Z180 processor). Seems this is what you are
> >> asking for (but maybe without the price):
> >>
> >> https://www.kksystems.com/programmable-protocol-converters/ppc-4-h2-c.html/
> >> https://www.kksystems.com/datasheets/pdf_files/ppclft.pdf
> >> https://www.kksystems.com/datasheets/pdf_files/ppcman.pdf
> >>> Alibaba is literally the last place I would by something like
> >>> this, for all the obvious reasons, including the risk of never
> >>> Yseeing the product or your money again.
> >>
> >> I bought many things from Aliexpress an nearly never had
> >> any problems.
> >
> > I'm pleased for you. People safely cross streets outside the crosswalk, yet people are killed doing that every day. Do you tell your kids it's a good thing to do?
> >
> Buying a $10 or a $100 thing at aliexpress is not that similar
> to getting killed, you know.
> I have bought a lot of small stuff there and have not yet been killed.
> Oh yes, and I do cross streets as I please and I am still alive, but
> that's not a very similar matter, as explained above.

My experience with Alibaba is not the same as yours. With Ebay, I can dispute a sale and get a refund. Alibaba spent literally months demanding more and more things from me, many which made no sense because of the language barrier. In the end, they said I failed to prove the vendor was lying when he said he shipped the item listed. Photos were not good enough. They wanted a video for some reason. Alibaba simply does not support their customers, so I don't use them. Ebay is worth while, but some things sold are perpetually fake, or crap and you have to buy them to find out, then make the "return", which the vendor is required to pay for, so they often say keep it.

I even bought crap wire on Ebay from a vendor relatively local. The actual wire gauge was about three numbers below the claimed AWG. Bought 20 gauge and got 23 gauge. Bought 18 gauge and got 21 gauge, etc. I was getting the refund, so I thought I'd try seeing how far this went. 16 gauge was actually 19 gauge and 12 gauge, was actually 15 gauge. The vendor could not say they didn't know, the wire insulation has *their* name on it! So it's a custom marked product. How could they not know they are selling mislabeled wire?

Yeah, they all sell crap. I just find it possible to get a refund from Ebay. Alibaba, not so much.

--

Rick C.

-+-+ Get 1,000 miles of free Supercharging
-+-+ Tesla referral code - https://ts.la/richard11209

On 1/21/2023 0:08, Rick C wrote:
> On Friday, January 20, 2023 at 4:02:27 PM UTC-5, Dimiter wrote:
>> On 1/20/2023 22:37, Rick C wrote:
>>> On Friday, January 20, 2023 at 1:17:59 PM UTC-5, Herbert Kleebauer wrote:
>>>> On 19.01.2023 19:06, Rick C wrote:
>>>>
>>>>
>>>>> 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.
>>>> Seems you are 25 years to late. But this company is still selling
>>>> its device (with a Z180 processor). Seems this is what you are
>>>> asking for (but maybe without the price):
>>>>
>>>> https://www.kksystems.com/programmable-protocol-converters/ppc-4-h2-c.html/
>>>> https://www.kksystems.com/datasheets/pdf_files/ppclft.pdf
>>>> https://www.kksystems.com/datasheets/pdf_files/ppcman.pdf
>>>>> Alibaba is literally the last place I would by something like
>>>>> this, for all the obvious reasons, including the risk of never
>>>>> Yseeing the product or your money again.
>>>>
>>>> I bought many things from Aliexpress an nearly never had
>>>> any problems.
>>>
>>> I'm pleased for you. People safely cross streets outside the crosswalk, yet people are killed doing that every day. Do you tell your kids it's a good thing to do?
>>>
>> Buying a $10 or a $100 thing at aliexpress is not that similar
>> to getting killed, you know.
>> I have bought a lot of small stuff there and have not yet been killed.
>> Oh yes, and I do cross streets as I please and I am still alive, but
>> that's not a very similar matter, as explained above.
>
> My experience with Alibaba is not the same as yours. With Ebay, I can dispute a sale and get a refund. Alibaba spent literally months demanding more and more things from me, many which made no sense because of the language barrier. In the end, they said I failed to prove the vendor was lying when he said he shipped the item listed. Photos were not good enough. They wanted a video for some reason. Alibaba simply does not support their customers, so I don't use them. Ebay is worth while, but some things sold are perpetually fake, or crap and you have to buy them to find out, then make the "return", which the vendor is required to pay for, so they often say keep it.
>
> I even bought crap wire on Ebay from a vendor relatively local. The actual wire gauge was about three numbers below the claimed AWG. Bought 20 gauge and got 23 gauge. Bought 18 gauge and got 21 gauge, etc. I was getting the refund, so I thought I'd try seeing how far this went. 16 gauge was actually 19 gauge and 12 gauge, was actually 15 gauge. The vendor could not say they didn't know, the wire insulation has *their* name on it! So it's a custom marked product. How could they not know they are selling mislabeled wire?
>
> Yeah, they all sell crap. I just find it possible to get a refund from Ebay. Alibaba, not so much.
>

I am not sure I'd bother to open a $10 dispute on aliexpress, I'd
expect your outcome plus wasted time. I can't remember buying anything
which costs > $100. They try to keep their reputation (aliexpress,
not alibaba) as they make their money on huge sale quantities
of small value all over the planet.
Recently I bought a nice keyboard at something like $40+,
can't believe I got something *that* good at this price (way
better than the Cherry-G84-s I have been using for decades now).
On alibaba the risks are way higher I guess, depends on luck.
My sister buys stuff from someone in Pakistan she found over alibaba
and she is happy (many years now). No surprise your experience has
been different.
I would not consider buying chips on either alibaba or aliexpress
of course. I bought some fast HV diodes on ebay twice and what
I got was not just OK but unobtainable otherwise....
Go figure, life is colourful and full of risks of various
probabilities and stakes.

Rick C <gnuarm.deletethisbit@gmail.com> wrote:
> On Friday, January 20, 2023 at 4:02:27 PM UTC-5, Dimiter wrote:
> > On 1/20/2023 22:37, Rick C wrote:
> > > On Friday, January 20, 2023 at 1:17:59 PM UTC-5, Herbert Kleebauer wrote:
> > >> On 19.01.2023 19:06, Rick C wrote:
> > >>
> > >>
> > >>> 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.
> > >> Seems you are 25 years to late. But this company is still selling
> > >> its device (with a Z180 processor). Seems this is what you are
> > >> asking for (but maybe without the price):
> > >>
> > >> https://www.kksystems.com/programmable-protocol-converters/ppc-4-h2-c.html/
> > >> https://www.kksystems.com/datasheets/pdf_files/ppclft.pdf
> > >> https://www.kksystems.com/datasheets/pdf_files/ppcman.pdf
> > >>> Alibaba is literally the last place I would by something like
> > >>> this, for all the obvious reasons, including the risk of never
> > >>> Yseeing the product or your money again.
> > >>
> > >> I bought many things from Aliexpress an nearly never had
> > >> any problems.
> > >
> > > I'm pleased for you. People safely cross streets outside the crosswalk, yet people are killed doing that every day. Do you tell your kids it's a good thing to do?
> > >
> > Buying a $10 or a $100 thing at aliexpress is not that similar
> > to getting killed, you know.
> > I have bought a lot of small stuff there and have not yet been killed.
> > Oh yes, and I do cross streets as I please and I am still alive, but
> > that's not a very similar matter, as explained above.
>
> My experience with Alibaba is not the same as yours. With Ebay, I can dispute a sale and get a refund. Alibaba spent literally months demanding more and more things from me, many which made no sense because of the language barrier. In the end, they said I failed to prove the vendor was lying when he said he shipped the item listed. Photos were not good enough. They wanted a video for some reason. Alibaba simply does not support their customers, so I don't use them. Ebay is worth while, but some things sold are perpetually fake, or crap and you have to buy them to find out, then make the "return", which the vendor is required to pay for, so they often say keep it.
>
> I even bought crap wire on Ebay from a vendor relatively local. The actual wire gauge was about three numbers below the claimed AWG. Bought 20 gauge and got 23 gauge. Bought 18 gauge and got 21 gauge, etc. I was getting the refund, so I thought I'd try seeing how far this went. 16 gauge was actually 19 gauge and 12 gauge, was actually 15 gauge. The vendor could not say they didn't know, the wire insulation has *their* name on it! So it's a custom marked product. How could they not know they are selling mislabeled wire?
>
> Yeah, they all sell crap. I just find it possible to get a refund from Ebay. Alibaba, not so much.
>

IIUC Alibaba is intended for larger transactions and has different
rules than Aliexpress. I did only small or very small transactions.
For me problem with Ebay was that with cheap shipping things would
not arrive and there were no way to dispute this. I can understand
this, without tracking there is no way to know who was to blame:
seller, mail or fraudolent customer. Tracked shipping was
significantly more expensive than goods that I wanted to buy.
OTOH things with cheap/free shipping ordered on Aliexpress were
arriving fine. So my conclusion was that Ebay sellers were at
fault and I stopped buying on Ebay.

There was period when also some shipments from Aliexpress vanished,
but AFAICS Aliexpress got this under control: they have reasonably
cheap tracked shipping and it seem that on all shipments they track
if package leaves China. That probably removes all incentives
for sellers to fail sending things.

Most Aliexpress seller have resonably high volumes. They sell
what customers want to buy. It can not be completely non functional,
there are not enough fools to support this. The problem is
that most customers are unable or unwillig to fully examine
what they bought. So you get rechargable batteries with
completely bogus stated capacity or USB chargers with inflated
charging current. I bought a lot of things on Aliexpress
but I am trying to keep realistic expectations. I bought
few USB chargers knowing that stated current (2.1 A) is
much bigger than real one (0.85 A), but they were good enough
for my purpose. I bought resistors and small power transistors.
My reasoning was that making something that looks like resistor
or transistor in small/medium volume is probably more expensive
than real resistor/transistor in high volume. And hopefully
there are not enough fools to fund high volume manufacturing
of fake transistors. Well, I got resistors and resonably
performing transistors. I can not say if there are some hidden
troubles but to the moment I am satisfied with what I bought.
In the past I bought few STM chips from Chinese sellers.
AFAIK those chips were widely used in China, the unit price was
much lower than unit price from western distributors, but
significantly higher that supposed volume price. So it
looked resonable that Chinese seller could sell them at lower
margin and still make a profit. And up to now I had no
problem with those chips.

OTOH if there is advanced/rare western part it would be strange
if Chinese seller had some magic cheap source of the part, so
I am very suspicious of such offers. Power mosfets were
borderline case. Around 2019 I bought packs of 10 from several
sellers. Essentially all were out of specs (too large Rds_on). If
there were moderate discrepancy I made comments stating real paramenter,
in few cases of really large discrepancy I requested partial
refund (and got it possibly after a dispute). To say the truth,
refunds that I got were probably not worth my time, I did this
mostly from feeling of moral duty, to make sure sellers know
that there is problem and to discourage them from selling such
bad parts.

When buying on Aliexpress it is useful to read buyers comments.
Especially Russians tend to measure/test bought parts, so you
can have resonable idea what you are buying.

BTW: classic Arduino boards are supposed to have Atmega 328P.
I have heard that recently a lot of boards instead had Chinese
chip. IIUC such boards also appeared in western distribution
channels, so it is possible that some Arduino boards that you
use is equpped with Chinese chip. On paper Chinese chip should
be better than Atmega 328P, but it has incompatiblities. For
simple use in Arduino it may be compatible enough, but in case
of troubles difference between chips is one of possible reasons.

--
Waldek Hebisch

On Friday, January 20, 2023 at 8:58:49 PM UTC-5, anti...@math.uni.wroc.pl wrote:
> Rick C <gnuarm.del...@gmail.com> wrote:
> > On Friday, January 20, 2023 at 4:02:27 PM UTC-5, Dimiter wrote:
> > > On 1/20/2023 22:37, Rick C wrote:
> > > > On Friday, January 20, 2023 at 1:17:59 PM UTC-5, Herbert Kleebauer wrote:
> > > >> On 19.01.2023 19:06, Rick C wrote:
> > > >>
> > > >>
> > > >>> 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.
> > > >> Seems you are 25 years to late. But this company is still selling
> > > >> its device (with a Z180 processor). Seems this is what you are
> > > >> asking for (but maybe without the price):
> > > >>
> > > >> https://www.kksystems.com/programmable-protocol-converters/ppc-4-h2-c.html/
> > > >> https://www.kksystems.com/datasheets/pdf_files/ppclft.pdf
> > > >> https://www.kksystems.com/datasheets/pdf_files/ppcman.pdf
> > > >>> Alibaba is literally the last place I would by something like
> > > >>> this, for all the obvious reasons, including the risk of never
> > > >>> Yseeing the product or your money again.
> > > >>
> > > >> I bought many things from Aliexpress an nearly never had
> > > >> any problems.
> > > >
> > > > I'm pleased for you. People safely cross streets outside the crosswalk, yet people are killed doing that every day. Do you tell your kids it's a good thing to do?
> > > >
> > > Buying a $10 or a $100 thing at aliexpress is not that similar
> > > to getting killed, you know.
> > > I have bought a lot of small stuff there and have not yet been killed..
> > > Oh yes, and I do cross streets as I please and I am still alive, but
> > > that's not a very similar matter, as explained above.
> >
> > My experience with Alibaba is not the same as yours. With Ebay, I can dispute a sale and get a refund. Alibaba spent literally months demanding more and more things from me, many which made no sense because of the language barrier. In the end, they said I failed to prove the vendor was lying when he said he shipped the item listed. Photos were not good enough. They wanted a video for some reason. Alibaba simply does not support their customers, so I don't use them. Ebay is worth while, but some things sold are perpetually fake, or crap and you have to buy them to find out, then make the "return", which the vendor is required to pay for, so they often say keep it.
> >
> > I even bought crap wire on Ebay from a vendor relatively local. The actual wire gauge was about three numbers below the claimed AWG. Bought 20 gauge and got 23 gauge. Bought 18 gauge and got 21 gauge, etc. I was getting the refund, so I thought I'd try seeing how far this went. 16 gauge was actually 19 gauge and 12 gauge, was actually 15 gauge. The vendor could not say they didn't know, the wire insulation has *their* name on it! So it's a custom marked product. How could they not know they are selling mislabeled wire?
> >
> > Yeah, they all sell crap. I just find it possible to get a refund from Ebay. Alibaba, not so much.
> >
> IIUC Alibaba is intended for larger transactions and has different
> rules than Aliexpress. I did only small or very small transactions.
> For me problem with Ebay was that with cheap shipping things would
> not arrive and there were no way to dispute this.

I've had exactly that problem. The only issue is that the vendor will ask you to wait another week or two, and repeat that process until the 60 day window has closed. So I say, no, I want a refund. Even if they don't cooperate, Ebay has always provided a refund. This has happened maybe four or five times. Once, the ordered item really did arrive.

> I can understand
> this, without tracking there is no way to know who was to blame:
> seller, mail or fraudolent customer. Tracked shipping was
> significantly more expensive than goods that I wanted to buy.
> OTOH things with cheap/free shipping ordered on Aliexpress were
> arriving fine. So my conclusion was that Ebay sellers were at
> fault and I stopped buying on Ebay.

The shipping on Ebay has improved. Very few of the vendors now use untracked shipping. But even if the tracking says it was delivered, you can still get a refund for an undelivered item. The shipping company does not always deliver to the right home or mailbox. Sometimes people give it to you, other times they don't. In any event, again, I've never been turned down for a refund by Ebay if I do everything right that I'm supposed to do, which is mostly, report it within 60 days of ordering.

Once a Japanese company shipped an item wrong. I don't recall the detail, but they wanted me to pay the return shipping which was not cheap. I dug my heals in and eventually lost. Don't recall the reason why. They stopped receiving my emails, or any other communications. So I opened another account, ordered the deluxe version of the same thing, shipped to another address. I made a claim with the credit card and got the refund. Then I sold this one to pay for the loss on the other one. Maybe that was dishonest, but I feel I was cheated on the first order, so justified.

I also ordered a Hantek attached oscilloscope, the low end model, to evaluate before buying a higher end model. I couldn't even get the software to load. No support to speak of, so I put in for a return. For whatever readson, the tracking was mucked and said it was never delivered. So I got the refund without an argument. Hantek is real crap goods, btw.

> There was period when also some shipments from Aliexpress vanished,
> but AFAICS Aliexpress got this under control: they have reasonably
> cheap tracked shipping and it seem that on all shipments they track
> if package leaves China. That probably removes all incentives
> for sellers to fail sending things.

No, they send something, just not anything of value. Aliexpress can't seem to understand the ICs which don't work, are counterfeit and you don't have to test every one on the reel to know they are all crap. The real issue was the language barrier. They don't speak English, rather use automated translators in both directions, so don't understand half of what you are saying. They also don't understand what an IC is and think counterfeit is only for handbags.

> Most Aliexpress seller have resonably high volumes. They sell
> what customers want to buy. It can not be completely non functional,
> there are not enough fools to support this.

LOL! If they buy counterfeit ICs at $0.05 each, they don't need to sell many at $5.00 to make profit.

> The problem is
> that most customers are unable or unwillig to fully examine
> what they bought. So you get rechargable batteries with
> completely bogus stated capacity or USB chargers with inflated
> charging current. I bought a lot of things on Aliexpress
> but I am trying to keep realistic expectations. I bought
> few USB chargers knowing that stated current (2.1 A) is
> much bigger than real one (0.85 A), but they were good enough
> for my purpose. I bought resistors and small power transistors.
> My reasoning was that making something that looks like resistor
> or transistor in small/medium volume is probably more expensive
> than real resistor/transistor in high volume. And hopefully
> there are not enough fools to fund high volume manufacturing
> of fake transistors.

I don't think you understand. There are any number of things that look like the thing they are selling you, which will pass a visual inspection if you close one eye and have no idea what you are looking for. But they are fake. Even a $0.10 transistor has a lot of markup if they only pay $0.001 each for a reject. It might work well enough to light the LED on a transistor tester.

> Well, I got resistors and resonably
> performing transistors. I can not say if there are some hidden
> troubles but to the moment I am satisfied with what I bought.

Sure, if you only need crap components, then you are good to go!

> In the past I bought few STM chips from Chinese sellers.
> AFAIK those chips were widely used in China, the unit price was
> much lower than unit price from western distributors, but
> significantly higher that supposed volume price. So it
> looked resonable that Chinese seller could sell them at lower
> margin and still make a profit. And up to now I had no
> problem with those chips.
>
> OTOH if there is advanced/rare western part it would be strange
> if Chinese seller had some magic cheap source of the part, so
> I am very suspicious of such offers. Power mosfets were
> borderline case. Around 2019 I bought packs of 10 from several
> sellers. Essentially all were out of specs (too large Rds_on). If
> there were moderate discrepancy I made comments stating real paramenter,
> in few cases of really large discrepancy I requested partial
> refund (and got it possibly after a dispute). To say the truth,
> refunds that I got were probably not worth my time, I did this
> mostly from feeling of moral duty, to make sure sellers know
> that there is problem and to discourage them from selling such
> bad parts.
>
> When buying on Aliexpress it is useful to read buyers comments.
> Especially Russians tend to measure/test bought parts, so you
> can have resonable idea what you are buying.

Theo <theom+news@chiark.greenend.org.uk> writes:
> 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.

The search is not for an RS232-to-RS232 product per se, but for a small
computer with two RS232 ports. In the Z80 era, those used to be
plentiful. Of course they were considered full fledged personal
computers, in large expensive boxes, given the technology of time.

The lament is that there doesn't seem to be anything like that being
made today with modern technology. Just a small box with a programmable
microprocessor inside, and two RS232 ports. All the available products
add a massive amount of additional complexity. It does seem like an
opportunity.

Imagining making something like that for myself makes me feel dismayed.
Besides the MCU board and enclosure, you also need a bunch of mounting
screws, standoffs, connectors, an enclosure made of sheet metal, tools
to drill holes for the standoffs and make D-shaped cutouts for the DB9
connectors, burn-in testing for everything, yada yada yada. All that
stuff would have to be ordered from someplace, maybe multiple places.

Whenever I try to make anything physical, I invariably discover partway
through that I need some 10 cent part that I didn't think of earlier, so
I have to order that and wait N days for its arrival, then repeat this
process several times. This is why custom made anything costs so much.
It's not like programming where if I need some chunk of software, I can
download it and have it a minute later.

It doesn't seem like THAT outlandish a wish to hope that box described
instead exists as an off the shelf product from somewhere. It is weird
that it is so hard to find.