On Tuesday, January 17, 2023 at 11:24:33 AM UTC-4, Rick C wrote:
> 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 was skimming the web for this again and I think I found something from Aaeon. Not sure why I didn't find this before. Maybe I did, but at that time was really looking for something with a simple CPU, rather than something to run a full OS. Beggars and choosers...

https://eshop.aaeon.com/ultra-slim-box-pc-boxer-6405.html

This one is $366, which is more than I'd like, but beggars... It is cheaper than the tailored unit a guy is working on for us. A sample unit doesn't work right and debugging across an ocean is not working very well. I could have this up and running in a day or something, as long as it comes with Linux installed.

They have a cheaper unit with a single serial port, $287.

https://eshop.aaeon.com/rockchip-android-system-boxer-rk88.html

Not sure if there is any real risk to sharing the serial port between the two devices. I know there's no handshaking. In fact, the Arduino shares a single serial port.

The only real problem is communications. Aaeon only has a couple each. So far, they have not responded to my requests for delivery on 20 units.

BTW, to those who contacted me about this and haven't heard back after the initial exchange, I'm sorry. I got busy with my own work and lost track of the emails. Of those who did reply, only one had a design in a box, ready for software. But that is not yet working.

--

Rick C.

+-+- Get 1,000 miles of free Supercharging
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Rick C <gnuarm.deletethisbit@gmail.com> writes:
> BTW, to those who contacted me about this and haven't heard back after
> the initial exchange, I'm sorry. I got busy with my own work and lost
> track of the emails. Of those who did reply, only one had a design in
> a box, ready for software. But that is not yet working.

You still want someone to do this custom? What is your budget and how
many units do you want? Did you ever find out more about the
requirements? I know a good who is good at this stuff. You are
probably looking at $1000 or more of NRE, but spread across a few dozen
units it might not be too bad, as the hardware itself should be quite cheap.

On Wednesday, March 22, 2023 at 11:35:18 PM UTC-4, Paul Rubin wrote:
> Rick C <gnuarm.del...@gmail.com> writes:
> > BTW, to those who contacted me about this and haven't heard back after
> > the initial exchange, I'm sorry. I got busy with my own work and lost
> > track of the emails. Of those who did reply, only one had a design in
> > a box, ready for software. But that is not yet working.
> You still want someone to do this custom? What is your budget and how
> many units do you want? Did you ever find out more about the
> requirements? I know a good who is good at this stuff. You are
> probably looking at $1000 or more of NRE, but spread across a few dozen
> units it might not be too bad, as the hardware itself should be quite cheap.

If you are talking about someone to build a board, no thanks. That is what I meant to say in the post, but I guess I glossed over that. I found a platform that is affordable, even if it is way overkill. A custom board design is not needed. Heck, a custom board design was never needed, except that RS-232 voltage levels are needed at the serial port I/Os. Otherwise, an Arduino of some variation, would be ideal.

I will just write the software myself with the $300 platform I guess. Being a PC type platform, running an OS, updating the software is just a matter of copying a file from an SD card or a USB memory stick. It could even be hooked up through the Ethernet port, although I'm not so familiar with that these days.

Years ago, I had a couple of desktop PCs running Win2k and from the info I found on the website World of Windows Networking, was able to connect them so the disk drives were available on either machine. I tried to do the same think a couple of years ago and it was much, much harder. Microsoft has made networking much more complex now.

I did manage to find my way through management speak and arrive at a very simple set of requirements. In fact, the problem with the guy we currently have working on the effort, is he added requirements of his own, that mess up the operation we intended. We might still use his solution, if he can get it to work for us. But he's in the UK and this is mucking up the debugging.

This device goes between a sensor, and an EDAS, which is just an industrial computer acting as an intermediary, collecting other data and sending it all on to other receivers of the data. A product update in the sensor (third party product) changed the data format. Before this new sensor was used, the translator was not needed. The translator makes the new sensor output compliant with the old sensor format which is expected downstream.

Serial formats are 9600, 8, N, 1. The input data is 1 line per second, output as soon as converted. A header is appended after each 20th input line. At these data rates, there will be no handshaking and no chance of any collisions.

New data format on incoming message example:
# 032023 174930 23.024 6.79 17.37 12.44
Terminated with /r/n

Old data format on output message example:
01/30/23 19:15:28 21.788 6.23 17.41 12.66
Terminated by /r/n

The modifications in the data are removing the "# " at the beginning and inserting '\' and ':' into the date and time fields.

Every 20 lines a header should be inserted and sent to the output. If something corrupts the line count, it's not a problem.

========================================== Date Time Temp SpCond pH ODO
m/d/y hh:mm:ss C mS/cm mg/L
-------------------------------------------
*** 1-LOG last sample 2-LOG ON/OFF, 3-Clean optics ***

Anything received that isn't in the input format specified above, should be sent on to the output. No other data should be sent to the output, such as boot messages. The only error checking should be that the line does not overflow the internal translator buffers. A watchdog timer could be used to reset the unit, if the software is lost in the weeds. The goal here is not for any data error checking, or other optimizations. If the old sensor produced any crap data, it didn't muck up the works before, and it shouldn't be a problem now, so just send it on.

I don't know for certain that the input data format is always the same length, so this should not be assumed. I would say an 80 character max length is a safe assumption. The /r/n should be the line delimiter. If garbage is received on the input before a message, it will prevent detection of the start of the message, which is fine. As soon as the next /r/n is received, it will be back in alignment. That's all that matters.

If I had more free time, I would have this done by now. lol

--

Rick C.

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

On Thursday, March 23, 2023 at 2:26:40 AM UTC-4, Rick C wrote:
> On Wednesday, March 22, 2023 at 11:35:18 PM UTC-4, Paul Rubin wrote:
> > Rick C <gnuarm.del...@gmail.com> writes:
> > > BTW, to those who contacted me about this and haven't heard back after
> > > the initial exchange, I'm sorry. I got busy with my own work and lost
> > > track of the emails. Of those who did reply, only one had a design in
> > > a box, ready for software. But that is not yet working.
> > You still want someone to do this custom? What is your budget and how
> > many units do you want? Did you ever find out more about the
> > requirements? I know a good who is good at this stuff. You are
> > probably looking at $1000 or more of NRE, but spread across a few dozen
> > units it might not be too bad, as the hardware itself should be quite cheap.
> If you are talking about someone to build a board, no thanks. That is what I meant to say in the post, but I guess I glossed over that. I found a platform that is affordable, even if it is way overkill. A custom board design is not needed. Heck, a custom board design was never needed, except that RS-232 voltage levels are needed at the serial port I/Os. Otherwise, an Arduino of some variation, would be ideal.
>
> I will just write the software myself with the $300 platform I guess. Being a PC type platform, running an OS, updating the software is just a matter of copying a file from an SD card or a USB memory stick. It could even be hooked up through the Ethernet port, although I'm not so familiar with that these days.
>
> Years ago, I had a couple of desktop PCs running Win2k and from the info I found on the website World of Windows Networking, was able to connect them so the disk drives were available on either machine. I tried to do the same think a couple of years ago and it was much, much harder. Microsoft has made networking much more complex now.
>
> I did manage to find my way through management speak and arrive at a very simple set of requirements. In fact, the problem with the guy we currently have working on the effort, is he added requirements of his own, that mess up the operation we intended. We might still use his solution, if he can get it to work for us. But he's in the UK and this is mucking up the debugging.
>
> This device goes between a sensor, and an EDAS, which is just an industrial computer acting as an intermediary, collecting other data and sending it all on to other receivers of the data. A product update in the sensor (third party product) changed the data format. Before this new sensor was used, the translator was not needed. The translator makes the new sensor output compliant with the old sensor format which is expected downstream.
>
> Serial formats are 9600, 8, N, 1. The input data is 1 line per second, output as soon as converted. A header is appended after each 20th input line. At these data rates, there will be no handshaking and no chance of any collisions.
>
> New data format on incoming message example:
> # 032023 174930 23.024 6.79 17.37 12.44
> Terminated with /r/n
>
> Old data format on output message example:
> 01/30/23 19:15:28 21.788 6.23 17.41 12.66
> Terminated by /r/n
>
> The modifications in the data are removing the "# " at the beginning and inserting '\' and ':' into the date and time fields.
>
> Every 20 lines a header should be inserted and sent to the output. If something corrupts the line count, it's not a problem.
>
> ===========================================
> Date Time Temp SpCond pH ODO
> m/d/y hh:mm:ss C mS/cm mg/L
> -------------------------------------------
> *** 1-LOG last sample 2-LOG ON/OFF, 3-Clean optics ***
>
> Anything received that isn't in the input format specified above, should be sent on to the output. No other data should be sent to the output, such as boot messages. The only error checking should be that the line does not overflow the internal translator buffers. A watchdog timer could be used to reset the unit, if the software is lost in the weeds. The goal here is not for any data error checking, or other optimizations. If the old sensor produced any crap data, it didn't muck up the works before, and it shouldn't be a problem now, so just send it on.
>
> I don't know for certain that the input data format is always the same length, so this should not be assumed. I would say an 80 character max length is a safe assumption. The /r/n should be the line delimiter. If garbage is received on the input before a message, it will prevent detection of the start of the message, which is fine. As soon as the next /r/n is received, it will be back in alignment. That's all that matters.
>
> If I had more free time, I would have this done by now. lol

The number of units required is initially 20, and probably another 20 in a few months. After that, not sure.

--

Rick C.

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

Rick C <gnuarm.deletethisbit@gmail.com> wrote:
> The number of units required is initially 20, and probably another 20 in a
> few months. After that, not sure.

We've been here before, but there are many many 'mini PCs' (often Celeron or
similar low power CPU) coming out of China that have multiple RS232 ports.
There doesn't seem to be much special about this one.

If such a 'mini PC' is within your spec (you were talking about
microcontrollers originally), it's just a case of finding a distributor who
meets your requirements. Easiest is to just go on Aliexpress [1] and buy
them, but if that's not your thing then I'm sure there is a US/wherever
importer.

If you're going to need many years worth of supply that's a bit trickier,
since they tend to update the product lines every time Intel releases a new
chip.

Theo

[1] https://www.aliexpress.com/w/wholesale-mini-pc-rs232.html

Rick C <gnuarm.deletethisbit@gmail.com> writes:
> If you are talking about someone to build a board, no thanks.

No, building a board would be crazy unless you're making 1000s of them.
Pick an Arduino or similar board with RS232 support, pick some enclosure
out of a catalog, put the stuff together, get the code running on the
board and test everything, etc. Then send the assembled unit to the
actual deployment site for in situ testing before making more units.

There is always some stuff going wrong or consuming time in any process
like that. Thus there will be some NRE.

Rick C <gnuarm.deletethisbit@gmail.com> writes:
> The number of units required is initially 20, and probably another 20
> in a few months. After that, not sure.

You are really willing to spend $300 per box in that quantity? So $6000
or $12000 depending? This sounds very doable.

Where is the deployment site geographically?

On Thursday, March 23, 2023 at 6:06:46 AM UTC-4, Theo wrote:
> Rick C <gnuarm.del...@gmail.com> wrote:
> > The number of units required is initially 20, and probably another 20 in a
> > few months. After that, not sure.
> We've been here before, but there are many many 'mini PCs' (often Celeron or
> similar low power CPU) coming out of China that have multiple RS232 ports..
> There doesn't seem to be much special about this one.

Yes, but initially I was looking for something more like an Arduino in a box. That never materialized. The solution we are looking at now, is a custom design someone did for another project, that suits our needs, but since the production quantities are low, the unit price is a bit steep, even if manageable.

> If such a 'mini PC' is within your spec (you were talking about
> microcontrollers originally), it's just a case of finding a distributor who
> meets your requirements. Easiest is to just go on Aliexpress [1] and buy
> them, but if that's not your thing then I'm sure there is a US/wherever
> importer.

LOL! Aliexpress is literally the last place I would go for commercial gear..

> If you're going to need many years worth of supply that's a bit trickier,
> since they tend to update the product lines every time Intel releases a new
> chip.
>
> Theo
>
> [1] https://www.aliexpress.com/w/wholesale-mini-pc-rs232.html

Useless, since you may not be able to buy the same unit even six months from now.

But thanks for the suggestion. I'm presently talking to Aaeon who has some affordable units.

--

Rick C.

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

On Thursday, March 23, 2023 at 11:54:54 AM UTC-4, Paul Rubin wrote:
> Rick C <gnuarm.del...@gmail.com> writes:
> > If you are talking about someone to build a board, no thanks.
> No, building a board would be crazy unless you're making 1000s of them.
> Pick an Arduino or similar board with RS232 support,

That's one of the problems. Boards like Arduinos do not have RS-232 support. They have serial ports, but that's what was tried initially, with a home brew RS-232 level shifter added on a perf board. Don't know why, but half of them tend to hang, even if after days. Not acceptable.

> pick some enclosure
> out of a catalog, put the stuff together, get the code running on the
> board and test everything, etc. Then send the assembled unit to the
> actual deployment site for in situ testing before making more units.

Sounds great. Do you have a proposal?

> There is always some stuff going wrong or consuming time in any process
> like that. Thus there will be some NRE.

Yeah, I'll just do the software myself. The cost difference between the Arduino and a minature PC is so small, it's more than made up in the savings of not having to do any of the stuff you mentioned other than write software.

--

Rick C.

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

On Thursday, March 23, 2023 at 12:00:35 PM UTC-4, Paul Rubin wrote:
> Rick C <gnuarm.del...@gmail.com> writes:
> > The number of units required is initially 20, and probably another 20
> > in a few months. After that, not sure.
> You are really willing to spend $300 per box in that quantity? So $6000
> or $12000 depending? This sounds very doable.
>
> Where is the deployment site geographically?

Multiple. Some are in the DC area.

--

Rick C.

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

Rick C <gnuarm.deletethisbit@gmail.com> writes:
> That's one of the problems. Boards like Arduinos do not have RS-232
> support.

I thought I had located one and posted a link here. I'll look again.

> Sounds great. Do you have a proposal?

I'm open to this but I'm probably not the best person for it, since I'm
mostly a software guy. Do you have a timeframe? I can also check with
other people I know who might be interested, and will refer them to you
by email if they are.

Am 24.03.2023 um 09:02 schrieb Rick C:
> On Thursday, March 23, 2023 at 11:54:54 AM UTC-4, Paul Rubin wrote:
>> Rick C <gnuarm.del...@gmail.com> writes:
>>> If you are talking about someone to build a board, no thanks.
>> No, building a board would be crazy unless you're making 1000s of them.
>> Pick an Arduino or similar board with RS232 support,
>
> That's one of the problems. Boards like Arduinos do not have RS-232 support. They have serial ports, but that's what was tried initially, with a home brew RS-232 level shifter added on a perf board.

Color me puzzled. Why on earth would anyone home-brew an RS232 level
shifter, particularly for a project that could clearly afford using
ready-made ICs like MAX232 instead?

Hans-Bernhard Bröker <HBBroeker@t-online.de> wrote:
> Am 24.03.2023 um 09:02 schrieb Rick C:
> > On Thursday, March 23, 2023 at 11:54:54 AM UTC-4, Paul Rubin wrote:
> >> Rick C <gnuarm.del...@gmail.com> writes:
> >>> If you are talking about someone to build a board, no thanks.
> >> No, building a board would be crazy unless you're making 1000s of them.
> >> Pick an Arduino or similar board with RS232 support,
> >
> > That's one of the problems. Boards like Arduinos do not have RS-232
> > support. They have serial ports, but that's what was tried initially,
> > with a home brew RS-232 level shifter added on a perf board.
>
> Color me puzzled. Why on earth would anyone home-brew an RS232 level
> shifter, particularly for a project that could clearly afford using
> ready-made ICs like MAX232 instead?

The problem is that commercial microcontroller boards like Arduinos tend to
have TTL level serial ports (or USB ones). If you want a box holding one of
those with some RS232 ports, you need to make a PCB with a MAX232 and a DB9,
and an enclosure to match. Rick was trying to find a box with all that
already done for him and drew a blank.

It's not the design that's the problem, it's the manufacturing.

Although for quantity 20 at these kind of price points, I might be tempted
to build something using dev boards, eg:
https://www.dfrobot.com/product-1030.html
and maybe a bit of 3D printing for an enclosure. For two of those boards
you might need to hand-patch one to use different pins, but it's not hard
and could be done.

If the customer is willing to pay $300 a unit it might be worth Rick's (or
somebody else's) time to do it. I'll be happy to take that contract, email
address works :-)

Theo

On Friday, March 24, 2023 at 7:45:03 AM UTC-4, Hans-Bernhard Bröker wrote:
> Am 24.03.2023 um 09:02 schrieb Rick C:
> > On Thursday, March 23, 2023 at 11:54:54 AM UTC-4, Paul Rubin wrote:
> >> Rick C <gnuarm.del...@gmail.com> writes:
> >>> If you are talking about someone to build a board, no thanks.
> >> No, building a board would be crazy unless you're making 1000s of them..
> >> Pick an Arduino or similar board with RS232 support,
> >
> > That's one of the problems. Boards like Arduinos do not have RS-232 support. They have serial ports, but that's what was tried initially, with a home brew RS-232 level shifter added on a perf board.
> Color me puzzled. Why on earth would anyone home-brew an RS232 level
> shifter, particularly for a project that could clearly afford using
> ready-made ICs like MAX232 instead?

That's what they used. I simply meant it was not a commercial product on a PCB. Half the units have some problem.

Did you think I meant they designed their own level shifter chip?

--

Rick C.

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

On Friday, March 24, 2023 at 10:20:37 AM UTC-4, Theo wrote:
> Hans-Bernhard Bröker <HBBr...@t-online.de> wrote:
> > Am 24.03.2023 um 09:02 schrieb Rick C:
> > > On Thursday, March 23, 2023 at 11:54:54 AM UTC-4, Paul Rubin wrote:
> > >> Rick C <gnuarm.del...@gmail.com> writes:
> > >>> If you are talking about someone to build a board, no thanks.
> > >> No, building a board would be crazy unless you're making 1000s of them.
> > >> Pick an Arduino or similar board with RS232 support,
> > >
> > > That's one of the problems. Boards like Arduinos do not have RS-232
> > > support. They have serial ports, but that's what was tried initially,
> > > with a home brew RS-232 level shifter added on a perf board.
> >
> > Color me puzzled. Why on earth would anyone home-brew an RS232 level
> > shifter, particularly for a project that could clearly afford using
> > ready-made ICs like MAX232 instead?
> The problem is that commercial microcontroller boards like Arduinos tend to
> have TTL level serial ports (or USB ones). If you want a box holding one of
> those with some RS232 ports, you need to make a PCB with a MAX232 and a DB9,
> and an enclosure to match. Rick was trying to find a box with all that
> already done for him and drew a blank.
>
> It's not the design that's the problem, it's the manufacturing.
>
> Although for quantity 20 at these kind of price points, I might be tempted
> to build something using dev boards, eg:
> https://www.dfrobot.com/product-1030.html
> and maybe a bit of 3D printing for an enclosure. For two of those boards
> you might need to hand-patch one to use different pins, but it's not hard
> and could be done.

This device is exactly what makes this difficult. Which pin on the DB9 is the data output?

> If the customer is willing to pay $300 a unit it might be worth Rick's (or
> somebody else's) time to do it. I'll be happy to take that contract, email
> address works :-)

You will need to post an email address. GG doesn't provide the email. Just HBBr...@t-online.de

--

Rick C.

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

On 22.03.2023 20:18, Rick C wrote:

> I was skimming the web for this again and I think I found something from Aaeon. Not sure why I didn't find this before. Maybe I did, but at that time was really looking for something with a simple CPU, rather than something to run a full OS. Beggars and choosers...
>
> https://eshop.aaeon.com/ultra-slim-box-pc-boxer-6405.html
>
> This one is $366, which is more than I'd like, but beggars... It is cheaper than the tailored unit a guy is working on for us. A sample unit doesn't work right and debugging across an ocean is not working very well. I could have this up and running in a day or something, as long as it comes
with Linux installed.

A lot of power consumption for such a task! An Atmel board
would only consume about 0.4 W, for example something like
that:

https://www.ledato.de/product_info.php?products_id=33
https://www.ledato.de/product_info.php?products_id=35

The price is crazy, but there should be similar
devices for only 1/5 of this price.

Rick C <gnuarm.deletethisbit@gmail.com> wrote:
> On Friday, March 24, 2023 at 10:20:37 AM UTC-4, Theo wrote:
>
> This device is exactly what makes this difficult. Which pin on the DB9 is the data output?

TXD (output of MAX2323ESE) is pin 2, RXD (input of MAX2323ESE) is pin 3.

ie would connect to a PC via a straight-through cable, not a null modem.

> > If the customer is willing to pay $300 a unit it might be worth Rick's (or
> > somebody else's) time to do it. I'll be happy to take that contract, email
> > address works :-)
>
> You will need to post an email address. GG doesn't provide the email. Just HBBr...@t-online.de

My email is on the bottom of http://www.markettos.org.uk/

(I am in the UK, if that makes a difference)

Theo

On 24.03.2023 17:16, Herbert Kleebauer wrote:

> https://www.ledato.de/product_info.php?products_id=33
> https://www.ledato.de/product_info.php?products_id=35

The same company (ledato.de, taskit.de) has also an ARM
board with Ubuntu and 2 (or 3) RS232 ports which is cheaper:

https://www.taskit.de/produkte/flex-iot/
https://youtu.be/Fsr8F6B7j0s

Am 24.03.2023 um 16:03 schrieb Rick C:
> On Friday, March 24, 2023 at 7:45:03 AM UTC-4, Hans-Bernhard Bröker
> wrote:
>> Am 24.03.2023 um 09:02 schrieb Rick C:

>>> That's one of the problems. Boards like Arduinos do not have
>>> RS-232 support. They have serial ports, but that's what was tried
>>> initially, with a home brew RS-232 level shifter added on a perf
>>> board.

>> Color me puzzled. Why on earth would anyone home-brew an RS232
>> level shifter, particularly for a project that could clearly afford
>> using ready-made ICs like MAX232 instead?
>
> That's what they used. I simply meant it was not a commercial
> product on a PCB. Half the units have some problem.
>
> Did you think I meant they designed their own level shifter chip?

You said you home-brewed the level shifter. How else was anybody to
interpret that?

Am 24.03.2023 um 15:20 schrieb Theo:

> The problem is that commercial microcontroller boards like Arduinos tend to
> have TTL level serial ports (or USB ones). If you want a box holding one of
> those with some RS232 ports, you need to make a PCB with a MAX232 and a DB9,
> and an enclosure to match. Rick was trying to find a box with all that
> already done for him and drew a blank.

Of course he did. Finding that kind of box off-the-shelf was a very
long shot, IMHO.

Industrialized versions of the Raspberry Pi might have come close, but
they're more likely to offer RS485 or 422, insead of 232.

On Friday, March 24, 2023 at 12:17:17 PM UTC-4, Herbert Kleebauer wrote:
> On 22.03.2023 20:18, Rick C wrote:
>
> > I was skimming the web for this again and I think I found something from Aaeon. Not sure why I didn't find this before. Maybe I did, but at that time was really looking for something with a simple CPU, rather than something to run a full OS. Beggars and choosers...
> >
> > https://eshop.aaeon.com/ultra-slim-box-pc-boxer-6405.html
> >
> > This one is $366, which is more than I'd like, but beggars... It is cheaper than the tailored unit a guy is working on for us. A sample unit doesn't work right and debugging across an ocean is not working very well. I could have this up and running in a day or something, as long as it comes
> with Linux installed.
> A lot of power consumption for such a task! An Atmel board
> would only consume about 0.4 W, for example something like
> that:
>
> https://www.ledato.de/product_info.php?products_id=33
> https://www.ledato.de/product_info.php?products_id=35
>
> The price is crazy, but there should be similar
> devices for only 1/5 of this price.

There should be many things in this world.

Rick C <gnuarm.deletethisbit@gmail.com> writes:
> This device is exactly what makes this difficult. Which pin on the
> DB9 is the data output?

The pinout is given here: https://wiki.dfrobot.com/RS232_Shield

How do you feel about using that board, with an Arduino? Digikey stocks
it, if that helps:

https://www.digikey.com/en/products/detail/dfrobot/DFR0258/6588574

How do you feel about recycling the enclosure from one of those port
selector switches discussed a while back?

Here is a Lilygo board which has an ESP32-C3 MCU and RS232 among
other things, for $17.98: https://www.lilygo.cc/products/t-rsc3

It is shipped from China so maybe doesn't fulfill requirements because
of that, but it at least shows that such a product exists.

Article about it with an Aliexpress redirect link (it is also sold
through there):

https://www.cnx-software.com/2023/01/20/lilygo-t-rsc3-esp32-c3-board-features-isolated-rs232-rs485-interfaces-5-to-24v-dc-input/

Direct Aliexpress

https://www.aliexpress.com/item/1005005136988162.html

Here is an Olimex MSP430 board with RS232 for around $32:

https://www.olimex.com/Products/MSP430/Starter/MSP430-5438-STK/

It is available at Mouser, though they only have 9 in stock right now:

https://www.mouser.com/ProductDetail/Olimex-Ltd/MSP430-5438STK?qs=BoUPAr39LHyy3j%2FN0eUzfQ%3D%3D

It is also on Digikey's site, but out of stock there.

There are more Olimex boards with RS232 that I didn't look up.

You mentioned that you didn't want to use an external FTDI cable on a
USB port. What about having an FTDI dongle inside the box, installed so
that its DB9 connector is panel mounted?

https://ftdichip.com/products/usb-com232-plus1/
https://ftdichip.com/products/db9-usb-f/

TTL to RS232 (?): https://www.sparkfun.com/products/449
Similar: https://www.waveshare.com/wiki/RS232_Board

Regarding the locations: are any in the western US?

On Friday, March 24, 2023 at 4:42:55 PM UTC-4, Paul Rubin wrote:
> Rick C <gnuarm.del...@gmail.com> writes:
> > This device is exactly what makes this difficult. Which pin on the
> > DB9 is the data output?
> The pinout is given here: https://wiki.dfrobot.com/RS232_Shield

You didn't answer the question. Which pin is the data output and which is the data input?

> How do you feel about using that board, with an Arduino? Digikey stocks
> it, if that helps:
>
> https://www.digikey.com/en/products/detail/dfrobot/DFR0258/6588574

Are you going to make the cable required?

> How do you feel about recycling the enclosure from one of those port
> selector switches discussed a while back?

Recycling is not a problem, as long as there is no branding on the box.

> Here is a Lilygo board which has an ESP32-C3 MCU and RS232 among
> other things, for $17.98: https://www.lilygo.cc/products/t-rsc3
>
> It is shipped from China so maybe doesn't fulfill requirements because
> of that, but it at least shows that such a product exists.
>
> Article about it with an Aliexpress redirect link (it is also sold
> through there):
>
> https://www.cnx-software.com/2023/01/20/lilygo-t-rsc3-esp32-c3-board-features-isolated-rs232-rs485-interfaces-5-to-24v-dc-input/
>
> Direct Aliexpress
>
> https://www.aliexpress.com/item/1005005136988162.html
>
> Here is an Olimex MSP430 board with RS232 for around $32:
>
> https://www.olimex.com/Products/MSP430/Starter/MSP430-5438-STK/
>
> It is available at Mouser, though they only have 9 in stock right now:
>
> https://www.mouser.com/ProductDetail/Olimex-Ltd/MSP430-5438STK?qs=BoUPAr39LHyy3j%2FN0eUzfQ%3D%3D
>
> It is also on Digikey's site, but out of stock there.
>
> There are more Olimex boards with RS232 that I didn't look up.
>
> You mentioned that you didn't want to use an external FTDI cable on a
> USB port. What about having an FTDI dongle inside the box, installed so
> that its DB9 connector is panel mounted?
>
> https://ftdichip.com/products/usb-com232-plus1/
> https://ftdichip.com/products/db9-usb-f/

Are you going to write the USB stack to run on the simple CPUs you have linked to?

> TTL to RS232 (?): https://www.sparkfun.com/products/449
> Similar: https://www.waveshare.com/wiki/RS232_Board

I don't know why you are showing all these devices.

> Regarding the locations: are any in the western US?

I don't know. Why does this matter? You won't be visiting the customer's site.

You seem to be thrashing around in looking at every little board that might or might not do the job, rather than finding one that will. The single port boards you've identified have the DB9 connector, but you don't indicate how you will split this into the two connectors required for the job.

Do you understand the requirements?

--

Rick C.

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

On 3/24/2023 8:08 AM, Rick C wrote:

>> Although for quantity 20 at these kind of price points, I might be tempted
>> to build something using dev boards, eg:
>> https://www.dfrobot.com/product-1030.html
>> and maybe a bit of 3D printing for an enclosure. For two of those boards
>> you might need to hand-patch one to use different pins, but it's not hard
>> and could be done.
>
> This device is exactly what makes this difficult. Which pin on the DB9 is the data output?

"Nominal" signal directions are specified from the standpoint of the *DTE*.
Remember that one rule and everything else falls into place. I.e., a DCE
*receives* data on the "Transmit Data" pin and transmits on the "Receive
Data" pin.

[Null Modem cables came into being because DTEs wanted to talk to DTEs.
So, *both* want to transmit on the TxD signal -- and thus need a pin
swap in the cable to connect out-to-in and in-to-out... even though
both are TxD]

DTE, by convention, use *male* connectors. That's the second thing to
remember.

Identify pin #1. Count sideways to the next pin; that will be RxD -- the
INPUT for the DTE device. The next pin will be TxD -- the OUTPUT for the
DTE device. (This for a DB9; using a DB25 changes this relative order).

It's not that hard (though folks tend to confuse themselves by getting
the frame of reference wrong -- esp when looking at UART chipsets
that want to label their pins TxD and RxD -- even if they are wired to
RxD and TxD, respectively, on the DB9, as is the case when implementing
a DCE).

Folks have historically bastardized all of these conventions -- for
"good reasons" (or, so they thought). But, a device (module) designed
for general use IN THE 21st CENTURY should have been designed with some
adherence to convention (i.e., male connector for DTE, female for DCE;
DTE transmits on TxD, DCE transmits on RxD). It's highly unlikely
that you're going to find a device that handshakes using SRTS or RLSD!

The roles of the control signals can quickly become confused as older
kit uses them in the original *interlocked* fashion of RS232C while
newer interpretations of the standard(s) have altered that behavior
(because most devices aren't as pathetically slow as 103 modems!)

[But, I think TWX, TELEX, et al. are long dead and gone]

Rick C <gnuarm.deletethisbit@gmail.com> writes:
> You didn't answer the question. Which pin is the data output and
> which is the data input?

The transmit pin (TXD, pin 2 in that table) is the output and the
receive pin (RXD, pin 3) is the input. Since it is a female connector,
by the standard, the box is considered data communications equipment
(DCE), rather than data terminal equipment (DTR). If it was DTR, the
two pins would be switched around. Is that what you are asking? In any
case, one always has to test to be sure.

>> https://www.digikey.com/en/products/detail/dfrobot/DFR0258/6588574
> Are you going to make the cable required?

A splitter cable? I thought I posted a url to order those from.

> Recycling is not a problem, as long as there is no branding on the box.

There could be a label with your own branding, strategically placed to
cover up any existing branding, if that works for you.

> Are you going to write the USB stack to run on the simple CPUs you
> have linked to?

It exists already on some of them. I wouldn't write a new one.

>> TTL to RS232 (?): https://www.sparkfun.com/products/449
>> Similar: https://www.waveshare.com/wiki/RS232_Board
> I don't know why you are showing all these devices.

There are tons of cpus with built in UARTs

> I don't know. Why does this matter? You won't be visiting the
> customer's site.

Somebody at some point might have to do that. I hope not, but the
saying is, hope for the best and plan for the worst.

Frankly the first thing I would try is taking one of your homebrew boxes
that is known to be failing, swapping out the homemade level shifter PCB
with one of the ones linked above, and seeing if that works. Or at
least, use a scope to check the voltages coming out of the homemade PCB.

> You seem to be thrashing around in looking at every little board that
> might or might not do the job, rather than finding one that will.

It is a two step process: 1) identify possible candidates; 2) pick one.

Posting links to those boards is in part a demonstration that such
boards exist.

> The single port boards you've identified have the DB9 connector, but
> you don't indicate how you will split this into the two connectors
> required for the job. Do you understand the requirements?

I believe so. There are premade splitter cables that separate pins 2
and 3 from a DB9 into two more DB9's, or such a thing can be made, or
(preferable) one can use a CPU with two serial ports (or USB split into
two ports). The splitter cable can be inside the box since IIRC you
don't want it flopping around on the outside. Then the two DB9's would
be on the rear panel.