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
If you're looking for an embedded solution, take a look at the FTDI modules.
--
------------------------------------------------------------------------------------ Free Software - Baxter Codeworks
------------------------------------------------------------------------------------
... snip ...
Impossible. USB is not a serial port.
--
[mail]: Chuck F (cbfalconer at maineline dot net)
[page]:
Try the download section.
** Posted from http://www.teranews.com **
see:
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/product.php?productid=16699
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 RS232serial 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:
?14.50, US232R-100 USB to RS232 Converter, 1m:
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:
Cables: TTL-232R and variants:
The FT232BM RS232USB chips drivers for many platforms is found here:
Virtual COM Port Drivers:
Glenn
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.
--
[mail]: Chuck F (cbfalconer at maineline dot net)
[page]:
Try the download section.
** Posted from http://www.teranews.com **
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.......
I use X-modem regularly over an FTDI chip and it has never failed.
Meindert
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.
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
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.
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.
I need an RS232 port for the following two reasons: * For use with the GT ROM program for re-flashing firmware * For programming PIC chips
The device that Don suggested looks very attractive but I'd just like ask one more question: My laptop has an "express card" slot. Would I be better off getting an RS232 adapter that goes into the express card slot, or should I go with the EasySync USB adapter?
I have had the best results with Keyspan. The p/n on the one I use says USA-19HS. It is the most reliable that I have used. It has a TI USB3410 inside with a MAX3243 that I believe is just the RS232 level translator.
Scott
I just did a google, as I wasn't sure if they were readily available, but found plenty, pricey however. $90USD for this one:
And I wouldn't know what sort of chip set these or others use. Some people may be aware.
Now have a look at mine:
Price includes world wide postage. It won't be the cheapest, but it works when most of the others fail. That is why I handle them. You can speak to the guys that designed the chipset, if you need in depth support.
Re-read the guarantee of the ability to return the goods if it doesn't work for your application. Our loss on postage, all you pay is return postage.
And re-read the customers feed back. I think there are 18 responses from Feb 2002, to Dec 2006. I simply stopped adding them. Applications that range from Garmin GPS's to Pfaff sewing machines. I doubt if anywhere else on the web, you will find a report such as this in the way of genuine feed back, on a USB to RS-232 converter. Please correct me if I am wrong.
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/product.php?productid=16699
Actually it is if one is being pedanting, and this is Usenet so the pedantic flag is set by default. ;)
None of the USB->serial adapters (FTDI, Prolific, or any other) will behave "exactly just line any other serial port". The timings and latencies are going to be _way_ different.
--
Grant Edwards grante Yow! Bo Derek ruined
at my life!
visi.com
Unless the UART handles that itself (decent ones do).
Ah, I think you misspelled "impossible".
--
Grant Edwards grante Yow! I would like to
at urinate in an OVULAR,
visi.com porcelain pool --
I'll give you another (and probably more relevant for this newsgroup) example: the low cost serial port programmers that use the modem and hardware flow control signals to drive a microcontroller's onboard programming capabilities. See (for example) the serial port based AVR programmers.
USB latency means that there's no way you are going to be able to run those over a USB to serial adapter, even if the adapter does a 100% accurate implementation of the modem and flow control signals.
Simon.
-- Simon Clubley, clubley@remove_me.eisner.decus.org-Earth.UFP Microsoft: Bringing you 1980's technology to a 21st century world
How true. 'U'niverial 'S'erial 'B'us Yep, definitely a serial port. :)
The only BIG problem I have ever had was the fact that most of the adapters we tested had some strange glitches occurring on the outputs at very consistent intervals. Like 50KHz and ~100KHz on two I recall. I presume this was some artifact introduced by the chipset and the polling rate of the USB system/driver. In some instances these spikes were interpreted as start bits and things didn't go well after that.
Jim
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.