Best usb to serial adapter.

[jedisurfer1]

I know there are some young but old school people here who still use a serial port. Alas I don't think any laptop comes with a serial port and I've used usb to serial but they don't always work.

Have you found one that works 100% of the time with all your devices?

[pianowizard]

I had the same dilemma when I needed to get a custom LabView program installed on my X31 to communicate with some lab equipment via a serial port. USB serial adapters didn't work reliably, but the serial port on the X31's dock did. It has been 5 years since then, and it hasn't given me problems even once.

So, get a dock for your laptop. Not a port replicator, but a real dock.

[tom lightbody]

if you have a PCMCIA slot, another way is a PCMCIA to serial adapter
such as eBay item #321416726898.

[jdrou]

From what I've read there are certain RS232 tasks that no USB-RS232 adapter can handle. I haven't had any issues with the ones I've used though with chips from Prolific and FTDI. The cheapest adapters that sometimes go by the name "Huge Pine" had some problems though so I quit using those.

[tarvoke]

this has actually become quite a problem. you can't always depend on what the vendor says/claims the chip is. boring history lesson:

for the longest time, prolific was the inexpensive decent one and everyone was happy. it even worked great in linux out of the box, no special driver installation needed. then a lot of clones and copies started appearing and mostly you couldn't tell the difference, although some didn't behave quite as well as the real thing.

then prolific started making drivers which would only work with a real prolific chip, at least insofar as they could identify fakes using software. (although this mainly only affected windows)

the above is all years and years old, if not older. so for all that time, lots of people already switched to ftdi based devices, because it was also inexpensive, didn't have broken drivers, worked great even in linux without any special binary blobs, etc. etc. and no one was making bad clones of ftdi.

then, recently, prolific started making drivers which, when it detected fake/clone chips, would not only not-work, but went as far as temporarily (permanently?) wipe out some super-low-level stuff in the usb eeprom side of things. (again, didn't affect linux - unless you went out of your way to install their own driver instead of just using the working built-in one linux already has.)

then, now that ftdi became so popular, people starting cloning the heck out of it as well. and I believe to the extent that recently the ftdi drivers are now also becoming deliberately broken. (also, only windows, I believe)

so at this point, it's less about what chip and more about what vendor you can trust. and even then, they could be getting fooled about what product they are buying&reselling. sometimes it might even be a real chip and not a copy, but missing some not-quite-vital electronics components that make it behave correctly (rather than "just good enough")

personally I'd feel safer getting a ftdi device from one of the popular new hobbyist places such as adafruit or sparkfun. even if their suppliers might not be trusted, those kind of places personally test each batch of incoming hardware themselves.

a legitimate one definitely should not be super expensive, but I'd steer clear of something selling for $5 on amazon or ebay. amazon would likely refund your 5 bucks no questions asked, but then you still wouldn't have a working adapter.

[tarvoke]

I had the same dilemma when I needed to get a custom LabView program installed on my X31 to communicate with some lab equipment via a serial port. USB serial adapters didn't work reliably, but the serial port on the X31's dock did. It has been 5 years since then, and it hasn't given me problems even once.

So, get a dock for your laptop. Not a port replicator, but a real dock.

and yes, ^^^this^^^ - totally a dock or ultrabase. although some ones for newer thinkpads lack serial, I think? e.g. x31 base has serial but so does the x31 itself. but x6 does not have serial, but the x6 bases do. I suspect the even newer x2xx/x3xx may still have serial lines in their docking connectors, just that the bases don't break them out into an actual port (good diy project, there, for the brave) - also not sure about some of the newer minidocks, but I think they don't either.

I'd much prefer serial on the x200 base than something like that weird-*** flimsy battery charger ribbon gone-wrong-thing that makes me feel like I'm going to break it just by looking at it. (at least the 1 single time I only ever had need to use it, ha. which was more just to test it, anyway.)
(and while I'm complaining, the x200 base is such a flimsy piece of hollow cheap plastic that barely even fits right, that if it hadn't come factory sealed in pristine lenovo packaging, I'd almost suspect it as a fake. almost.)

[jdrou]

if you have a PCMCIA slot, another way is a PCMCIA to serial adapter
such as eBay item #321416726898.

For newer laptops there are also ExpressCard RS232 adapters.
Many of these actually seem to use USB though; e.g. http://www.synchrotech.com/products-exp ... er_01.html
driver download refers to PL2303 which is a Prolific USB convertor chip.
Startech EC1S232U2 also says "USB-based" and uses that same chip.
OTOH you have this:
http://www.synchrotech.com/products-pci ... 32_01.html
which looks like it might be a true PCIe adapter. Other cards with "native" in description or referring to the same chip are probably also good (Startech EC1S952). Startech EC2S55254 is probably also good.

Or grab an old Latitude D630 from ebay (one of the last laptops with RS232 port).

[donzoomik]

My employer uses a lot of RS232 based industrial systems and USB-RS232 converters have become commonplace. While there are still industrial rugged laptops that have physical RS232 (think Panasonic Toughbook CF-19, Getac V110 etc), they are very expensive (volume prices start at 2000-2500€ per unit, ~3000-4000€ for retail unit is not uncommon) and quite rare in consumer hands (Offroaders like them). We have several hundred of them, and their RS232 work great.

Coming back to USB-RS232 - from my experience, the only chipset that works properly is FTDI. Prolific and every other chipset has had their problems with one or other device.

[RealBlackStuff]

The T23 Thinkpads come natively with a Serial Port (T30 was the last model).
These laptops are great for car tuning etc.
I have at least 10 of those T23s, all in good to very good condition.
If someone is interested in the lot, make me an offer I cannot refuse!

[FryPpy]

I have some Prolific and FTDI chip adapters and all worked ok. There is some problems with old PL chips and newer version of windows.

T30 was the last model

Yes, but if we'll see in depth. COM port have taken from super IO chip. It use LPC bus (neither USB nor PCI/PCIe). 40, 60 500 series have transfered LPC bus to the dock. Other super IO chip in the dock (ex PC87392 n X6x dock) making RS232 from LPC there. But T60 and T61 have other connector with LPC bus -> in the ultrabay. There is ULTRABAY LPT and COM adapter that must work like old T30 COM port. I have one (ultrabay adapter) and have used it couple of times with success.
I haven't seen LPC bus in X20x docking connector - so no oldschool COM port there:(

CONCLUSIONS (for ThinkPads).
If one need mobility and ultrabay (for bigger HDD or CD/DVD) search for T30 (T23).
If one need computational power, internal COM port and mobility (servicing robots or cars) - search for our beloved T6x series (may be some R6x have this connector) and ultrabay adapter.
If one need computational power, mobility (i think X61s with ultrabay may be on par with T30), ultrabay and small size search for X6x inc. X6x tablet and dock (BTW X6x and X6x tablet have different docks!!!).
If one need even more computational power for non mobile use case (lab work) search for T(W)500 (T6x or even R6x can do work) and dock.

PS
Interesting things - PC87392 have MIDI (and game port), FDC and FDC PPM (FDC over LPT) functions. There is no game port connector on X6x dock. But have anybody tested Floppy disk drive from old thinkpads on LPT port of X6x dock?

[sysiphus]

If you need a modern machine with a serial port, the best solution I know is an HP EliteBook 8570p:

15" Ivy Bridge business-class machine with built-in RS232. Seriously. The 8570w workstation variant (higher processor configs, workstation graphics) omits it, but the -p model has it. If you want to save some money, the immediate predecessor 8560p is the same design but on Sandy Bridge instead. I've never used one myself, but the 8560w (same platform but Sandy Bridge workstation) is excellent, as is my 8460w (see signature). Build quality is easily equal to that of a T61-era ThinkPad, albeit accomplished with more metal and less plastic, so at the expense of a bit more heft. Still, great machines that depreciated quickly and are reasonably easy to find. And dead simple to work on/upgrade, too.