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Please suggest USB to RS232 adapter that works 100%

 
 
Tomás Ó hÉilidhe
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      06-13-2008, 12:39 AM

I've purchased one already made by "Cypress Semiconductor" but it
doesn't work. The VID is 04b4 and the PID is 5500.

Can anyone suggest a USB to RS232 adapter that does its job perfectly
100% of the time under Microsoft Windows, i.e. it trully behaves
exactly just like any other serial port?
 
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drn@nadler.com
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      06-13-2008, 01:11 AM
On Jun 12, 8:39 pm, Tomás Ó hÉilidhe <(E-Mail Removed)> wrote:
> I've purchased one already made by "Cypress Semiconductor" but it
> doesn't work. The VID is 04b4 and the PID is 5500.
>
> Can anyone suggest a USB to RS232 adapter that does its job perfectly
> 100% of the time under Microsoft Windows, i.e. it trully behaves
> exactly just like any other serial port?


We've had no end of problems with USB to RS232 adapters
that only work sometimes, or at certain baud rates, etc. The
best we've found is Belkin. If you're lucky you'll get one with
current software. No idea if Vista drivers are available or working,
but under XP Belkin is OK.

Hope this helps !
Best Regards, Dave
 
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Don McKenzie
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      06-13-2008, 05:03 AM
Tomás Ó hÉilidhe wrote:
> I've purchased one already made by "Cypress Semiconductor" but it
> doesn't work. The VID is 04b4 and the PID is 5500.
>
> Can anyone suggest a USB to RS232 adapter that does its job perfectly
> 100% of the time under Microsoft Windows, i.e. it trully behaves
> exactly just like any other serial port?


see:
http://www.dontronics-shop.com/easys...0cm-cable.html

I can't guarantee 100%, and nobody can, but this is what it says on my
advertised page:

Dontronics Guarantee: These converters are packed in a plastic envelope
that can easily be re-packed without any damage. If you purchase this
product, and it doesn't work for you, return it in a re-sellable
condition, that is, in the same condition that it was delivered to you,
and will will refund your money in full, provided you return it within 7
days of receiving it.

and read the user comments/feed back near the bottom of the page.

These use the FTDI chips, and in fact are manufactured by FTDI under the
Easysync brand name.

Cheers Don...


--
Don McKenzie

Site Map: http://www.dontronics.com/sitemap
E-Mail Contact Page: http://www.dontronics.com/email

Intelligent 2.83" AMOLED with touch screen for micros:
http://www.dontronics-shop.com/produ...roductid=16699
 
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Glenn Møller-Holst
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      06-13-2008, 06:49 AM
CBFalconer wrote:
> Tomás Ó hÉilidhe wrote:
> ... snip ...
>> Can anyone suggest a USB to RS232 adapter that does its job
>> perfectly 100% of the time under Microsoft Windows, i.e. it
>> trully behaves exactly just like any other serial port?

>
> Impossible. USB is not a serial port.


Hi!

He properly means that he wants to have the RS232 tunnelled through USB
and showing itselves as a serial port in Windows.


Look at this ftdi.com based RS232<->serial converter. The VCP drivers
installed on your PC simply tunnels your RS232 serial port through USB
to a virtual com-port in e.g. Windows.

(This was found at the Web-shop: http://www.ftdichip.com/FTProducts.htm ):

?14.50, US232R-100 USB to RS232 Converter, 1m:
http://apple.clickandbuild.com/cnb/s...B+RS232+cables
Quote: "...
The electronics, including the FT232RQ chip are housed in an attractive
glossy white enclosure with blue, side-lit LED TX and RX traffic
indicators. A matching white 1m USB cable uses gold plated USB and DB9
connectors.

The US232R-100 evaluation cable is supplied in retail packaging which
includes instructions together with a Drivers and Utilities CD complete
with Microsoft WHQL certified VCP drivers for Windows XP. Drivers for
the Apple Mac, Linux and other versions of Windows are also included on
the CD.
....."

Cables: UC232R:
http://apple.clickandbuild.com/cnb/s...5&title=UC232R

Cables: TTL-232R and variants:
http://apple.clickandbuild.com/cnb/s...R+and+variants

-

The FT232BM RS232<->USB chips drivers for many platforms is found here:

Virtual COM Port Drivers:
http://www.ftdichip.com/Drivers/VCP.htm
http://www.ftdichip.com/

-

Glenn
 
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TT_Man
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      06-13-2008, 08:07 AM

"Tomás Ó hÉilidhe" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
>
> I've purchased one already made by "Cypress Semiconductor" but it
> doesn't work. The VID is 04b4 and the PID is 5500.
>
> Can anyone suggest a USB to RS232 adapter that does its job perfectly
> 100% of the time under Microsoft Windows, i.e. it trully behaves
> exactly just like any other serial port?



I've found those with PROLIFIC chip sets work well with my obscure hardware.
Controlling rts/cts/dsr/dtr correctly is always seems to be the issue.......


 
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Meindert Sprang
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      06-13-2008, 08:49 AM
"CBFalconer" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> I'm hearing some objections to my statement above. My point is
> that USB is a shared system, and that it queues up traffic for
> transmission at intervals. You can't use the adaptor to respond to
> an input event in microseconds, as you can with the original port.
> What you can do is asynchronous transmission and reception, which
> is most people's objective.
>
> For example I believe that the original X-modem protocol will fail
> miserably. That requires responding to a transmission with an ACK
> (or NAK) within a very short time. Z-modem will probably work.


I use X-modem regularly over an FTDI chip and it has never failed.

Meindert


 
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David Brown
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      06-13-2008, 09:03 AM
Meindert Sprang wrote:
> "CBFalconer" <(E-Mail Removed)> wrote in message
> news:(E-Mail Removed)...
>> I'm hearing some objections to my statement above. My point is
>> that USB is a shared system, and that it queues up traffic for
>> transmission at intervals. You can't use the adaptor to respond to
>> an input event in microseconds, as you can with the original port.
>> What you can do is asynchronous transmission and reception, which
>> is most people's objective.
>>
>> For example I believe that the original X-modem protocol will fail
>> miserably. That requires responding to a transmission with an ACK
>> (or NAK) within a very short time. Z-modem will probably work.

>
> I use X-modem regularly over an FTDI chip and it has never failed.
>


It will depend on the level of sharing. If you have an FTDI device
plugged directly into a root port on your PC, then it will get the full
12 Mbs for full speed USB. Latency will then normally be of the order
of a millisecond or two, since that's the polling rate of USB (at least,
for 12 Mbs USB - I don't know if it is faster for 480 Mbs USB).

If you share the same root port via a USB hub which is also used for a
USB memory stick and transfer large files at the same time, you'll see
far more latency and throughput issues as the bandwidth is shared. How
much that may affect the serial protocol used depends entirely on its
timing requirements.

Even at best, with a direct connection to a root port, USB works with
timing in the range of a few milliseconds. For most uses, it works fine
- but as Chuck says it is not going to be 100% identical to a direct
serial link.
 
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Paul Keinanen
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      06-13-2008, 09:43 AM
On Fri, 13 Jun 2008 03:53:32 -0400, CBFalconer <(E-Mail Removed)>
wrote:

>CBFalconer wrote:
>> Tomás Ó hÉilidhe wrote:
>>
>> ... snip ...
>>
>>> Can anyone suggest a USB to RS232 adapter that does its job
>>> perfectly 100% of the time under Microsoft Windows, i.e. it
>>> trully behaves exactly just like any other serial port?

>>
>> Impossible. USB is not a serial port.

>
>I'm hearing some objections to my statement above. My point is
>that USB is a shared system, and that it queues up traffic for
>transmission at intervals. You can't use the adaptor to respond to
>an input event in microseconds, as you can with the original port.
>What you can do is asynchronous transmission and reception, which
>is most people's objective.
>
>For example I believe that the original X-modem protocol will fail
>miserably. That requires responding to a transmission with an ACK
>(or NAK) within a very short time. Z-modem will probably work.


I also very much doubt that you could use it with an external
RS-232/485 converter with data direction control using the RTS line.
Doing it properly is very hard even on any 14550 style UART,
especially on any multitasking OS.

Also implementing Modbus RTU with proper timing is going to be a
challenge :-).

Paul

 
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David Brown
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      06-13-2008, 10:33 AM
Paul Keinanen wrote:
> On Fri, 13 Jun 2008 03:53:32 -0400, CBFalconer <(E-Mail Removed)>
> wrote:
>
>> CBFalconer wrote:
>>> Tomás Ó hÉilidhe wrote:
>>>
>>> ... snip ...
>>>
>>>> Can anyone suggest a USB to RS232 adapter that does its job
>>>> perfectly 100% of the time under Microsoft Windows, i.e. it
>>>> trully behaves exactly just like any other serial port?
>>> Impossible. USB is not a serial port.

>> I'm hearing some objections to my statement above. My point is
>> that USB is a shared system, and that it queues up traffic for
>> transmission at intervals. You can't use the adaptor to respond to
>> an input event in microseconds, as you can with the original port.
>> What you can do is asynchronous transmission and reception, which
>> is most people's objective.
>>
>> For example I believe that the original X-modem protocol will fail
>> miserably. That requires responding to a transmission with an ACK
>> (or NAK) within a very short time. Z-modem will probably work.

>
> I also very much doubt that you could use it with an external
> RS-232/485 converter with data direction control using the RTS line.
> Doing it properly is very hard even on any 14550 style UART,
> especially on any multitasking OS.
>


You can do RTS control of RS-485 drivers, but you have even less
accurate timing with USB than with a standard UART.

An alternative is to use a feature of the FTDI chips - they can drive a
RS-485 direction line directly whenever they are transmitting.

> Also implementing Modbus RTU with proper timing is going to be a
> challenge :-).
>
> Paul
>

 
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James Beck
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      06-13-2008, 02:29 PM
In article <9bd63d75-3975-47d3-810a-361318b93f1f@
34g2000hsf.googlegroups.com>, (E-Mail Removed) says...
>
> I've purchased one already made by "Cypress Semiconductor" but it
> doesn't work. The VID is 04b4 and the PID is 5500.
>
> Can anyone suggest a USB to RS232 adapter that does its job perfectly
> 100% of the time under Microsoft Windows, i.e. it trully behaves
> exactly just like any other serial port?
>

Keeping in mind the other posts in this thread AND that your mileage may
vary; we use, and have never had a SINGLE problem with, the ATEN
adapters. It may just be luck, or I just haven't tried the magic combo
that blows it up, but those units have been rock solid performers for
us. I don't know what chipset the units use and really don't care,
because they work. They are a bit pricier than most of the crap out
there.

Just google or search on amazon:

ATEN UC-232A

and you will get plenty of info.

 
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