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Will the Serial Console Ever Die?

kdawson posted more than 4 years ago | from the can-you-say-are-ess-two-three-two dept.

Input Devices 460

simpz writes "Will the serial port as a console connection ever be displaced — especially for devices such as switches, routers, SAN boxes, etc.? In one sense it's a simple connection. But it is the only current port that, in order to use, you need to know about wiring / baud rates / parity, etc. It has non-standard pinouts. And it is becoming too slow to upload firmware to dead devices, as the firmware updates get larger. Also, the serial port is rapidly disappearing from new laptops — which is where you often really need it, in data centers. Centronics, PS/2, and current loop are mostly defunct. Is there any sign on the horizon of a USB console connection?"

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You can buy a serial-to-usb converter for $15 (4, Informative)

tomhudson (43916) | more than 4 years ago | (#31301826)

I use one just fine with an old WACOM 12" tablet under linux, so while the port may be dead, we can still use serial software and hardware. There's no reason you can't use two $15 converters plus a null modem to run that old DOS-based serial telecom program (ah, telix ... thanks for the memories).

Re:You can buy a serial-to-usb converter for $15 (5, Informative)

Anonymous Coward | more than 4 years ago | (#31301908)

Also there are single chip rs232 to USB solutions available for a few dollars. They are used in lots of things these days. They are great for when the device your making only needs a simple serial port connection to a pc or other device. Arduino uses one on their boards. I cant really think of any other examples at the moment. But I dont see serial console dying anytime soon, its still really useful to have around.

Re:You can buy a serial-to-usb converter for $15 (0)

Anonymous Coward | more than 4 years ago | (#31302192)

The Sheeva Plug dev kit uses one

Re:You can buy a serial-to-usb converter for $15 (0)

Anonymous Coward | more than 4 years ago | (#31302200)

A lot of GPS devices use these as well (I've got a DG-100).

Re:You can buy a serial-to-usb converter for $15 (4, Informative)

transporter_ii (986545) | more than 4 years ago | (#31301936)

I would like to point out that, while converters work just fine for almost everything, they do not work for everything. I've personally ran into equipment that would not read with a serial to USB converter. I've worked a little in SCADA, and you just about had to special order a laptop with a real serial port on it, or you just couldn't read all the equipment in the field.

But if you know what you are wanting to use with a converter works, then they usually work just fine.

Re:You can buy a serial-to-usb converter for $15 (3, Interesting)

tomhudson (43916) | more than 4 years ago | (#31302010)

It depends on the serial-to-usb converter chip used. Some don't do a good job of replicating all the characteristics of the port. Best advice is try different types until you find one that works. The newer ones do a good job - the older ones were really hit-and-miss (mostly miss) affairs.

Re:You can buy a serial-to-usb converter for $15 (5, Informative)

russotto (537200) | more than 4 years ago | (#31302112)

It depends on the serial-to-usb converter chip used. Some don't do a good job of replicating all the characteristics of the port. Best advice is try different types until you find one that works.

The biggest problem I've found even with the good ones is timing sensitive stuff. In some OSs (Linux included), when a synchronous write to a serial port concluded, pretty much all but the last character was already out on the line. With a USB serial port, the data is probably buffered on the device; it will go out many milliseconds later (because serial is slow). So if you've built timeouts into your code, they're all wrong now.

Re:You can buy a serial-to-usb converter for $15 (2, Interesting)

Zerth (26112) | more than 4 years ago | (#31302216)

Yarg, I've got some industrial machinery that uses serial and I've yet to find a converter that has timing exactly like a real serial port. Know any with very exact timing(not bloody likely with USB)?

Fortunately, most of our newer machinery runs on straight cat5.

Re:You can buy a serial-to-usb converter for $15 (2, Interesting)

ScrewMaster (602015) | more than 4 years ago | (#31302268)

Yarg, I've got some industrial machinery that uses serial and I've yet to find a converter that has timing exactly like a real serial port. Know any with very exact timing(not bloody likely with USB)?

Fortunately, most of our newer machinery runs on straight cat5.

I'd guess you're running Modbus, or something similar.

Re:You can buy a serial-to-usb converter for $15 (1)

RightwingNutjob (1302813) | more than 4 years ago | (#31302312)

A microcontroller intermediary would probably be the best way to go: PC -> usb ->usb2serial -> microcontroller -> serial -> machinery A bunch of PICs come with two built-in UARTs, and can be coded to do exact timing on the side where it matters.

It should have been phased out... (1)

joocemann (1273720) | more than 4 years ago | (#31301830)

... about a decade ago.

Re:It should have been phased out... (1, Funny)

yuhong (1378501) | more than 4 years ago | (#31302014)

And Apple did with the iMac in 1998. I wonder what was Steve Jobs' reaction when he was told that the Xserve is going to have a serial port, considered "legacy" by Apple since the iMac in 1998.

Re:It should have been phased out... (5, Interesting)

Anonymous Coward | more than 4 years ago | (#31302060)

Screw that. I do programming for embedded systems and serial is absolutely essential. Even the simplest bootloader supports standard serial. Hell, you can write an implementation of rs232 in an fpga in about 20 minutes. Its ubiquitous because requires no real software to make it work...and when you have barely any software working on a system, that uart can be the difference between hours and weeks of debugging.

Re:It should have been phased out... (2, Interesting)

X0563511 (793323) | more than 4 years ago | (#31302246)

My phone (Palm Pre) can even pull bootloader code over USB, so even if the boot flash gets hosed, it can recover via USB.

Serial shouldn't be needed outside of microprocessor development these days... that it is is sad.

Sure, a board may cost $0.50 more to manufacture... yea, stop penny-fraction-pinching you bastards!

Re:It should have been phased out... (4, Informative)

Jhon (241832) | more than 4 years ago | (#31302260)

I can't speak to switch access, but the serial port is paramount in the medical instrumentation field. Virtually all interfaces are serial. Need to hook up a CBC machine? Cobas? Vitek? Serial!

Most machine shops -- their equipment is serial. Sending cut information to the lathe? Serial.

Serial Ports.. (1)

lionchild (581331) | more than 4 years ago | (#31301834)

What do you mean 'serial ports are rapidly disappearing..' They're all but gone, aren't they?! :-/

Re:Serial Ports.. (4, Informative)

unr3a1 (1264666) | more than 4 years ago | (#31301852)

He means on desktops, laptops, servers, and shit like that. Other than cisco routers and switches, you can't really fine hardware that has a serial port on it. But all routers and switches are still manufactured with serial...

Re:Serial Ports.. (2, Informative)

Anonymous Coward | more than 4 years ago | (#31301916)

"Other than cisco routers and switches, you can't really fine hardware that has a serial port on it."

Every piece of DC-worthy gear I've touched has had serial.

Of course, most stuff either comes with serial *and* ethernet, or allows one to hop in via serial and set up a web-based interface, but serial is always there.

Re:Serial Ports.. (0)

unr3a1 (1264666) | more than 4 years ago | (#31302006)

Then you are looking at old catalogs my friend.... no, serial is not included on every piece of hardware.

Re:Serial Ports.. (1)

Ethanol-fueled (1125189) | more than 4 years ago | (#31302078)

My last two gigs involved test and repair of very "modern" devices which still used serial ports for communication and firmware uploads. The whole fixed width scrolling terminal thing to check values and send commands to the device. Only recently did one of them update the GUI to a fixed(updating) number of fields instead of outputting the raw data line-by line(which, of course, is more useful when looking for intermittent problems).

And it is becoming too slow to upload firmware to dead devices, as the firmware updates get larger.

Bah, that's only for the loser end-users who can't void the warranties opening the box. Technicians get to use PICkits [] and PM3's [] . Much quicker, man.

Re:Serial Ports.. (0)

Anonymous Coward | more than 4 years ago | (#31302352)

Wow really? Try every single RGB/DVI video router, everything by Ashly, every server built, every IR device, everything from Extron ...

Re:Serial Ports.. (3, Informative)

interiot (50685) | more than 4 years ago | (#31301928)

When it comes to managing important network switches, no, they aren't gone.

When an important switch fails for some reason, how do you contact it to see if it's recoverable remotely? (i.e. when your network admin has to manage switches that are located at remote satellite offices)

Out-of-band management addresses this limitation by employing a management channel that is physically isolated from the data channel. []

Re:Serial Ports.. (3, Interesting)

zappepcs (820751) | more than 4 years ago | (#31302302)

An awesome point that can't be overstated. Well, probably not anyway. There are modems, converters, terminal servers and several other ways to use a serial port on important hardware. Out of band management is one of the best reasons for ever using it. The dial up modem as fall back to access servers has not been replaced yet. I imagine that there are a few reading these posts that know serial backup saved their bacon more than once.

Re:Serial Ports.. (1)

deniable (76198) | more than 4 years ago | (#31302030)

"the serial port is rapidly disappearing from new laptops" in full, and yes, they've been gone from most laptops for years now. We have to salvage old gear if we need to talk to a serial port. USB -> Serial mostly works, but not always.

RE: Will the Serial Console Ever Die? (1)

unr3a1 (1264666) | more than 4 years ago | (#31301836)

I would think so... It's a good question to ask. Same way with IDE ports on motherboards... I mean does ANYONE ever use a floppy disk anymore?

Re: Will the Serial Console Ever Die? (0)

Anonymous Coward | more than 4 years ago | (#31301882)

Floppy isn't IDE. Also, even now a lot of optical drives out there still use IDE.

Re: Will the Serial Console Ever Die? (1)

unr3a1 (1264666) | more than 4 years ago | (#31301978)

PATA/IDE... whatever, its the same difference. And no, most optical drives out there are now SATA. Got a new computer a couples months ago, and it has a SATA optical. Goto newegg... the SATA drives outnumber PATA almost 3-1. And the majority of motherboards still carry a PATA port of some kind. Maybe they include it because almost all modern CMOS's still only look towards a floppy disk when there is a full system crash... so maybe its for last resort emergency situations with computers???

Re: Will the Serial Console Ever Die? (0)

Anonymous Coward | more than 4 years ago | (#31302168)

PATA != FDC port. Both still have uses. BIOS recovery is one. The boot block contains a very primitive recovery mechanism for bad flashes. A floppy is one of the easiest devices to code for and FAT12 is a well understood filesystem that is easy for simple code to grep. Unlike floppies, hard drives can contain any number of filesystems all of which are far more complex. Flash devices sound like a great replacement until you realize that USB support must also be included which is almost impossible to fit into the tiny boot block.

there are plenty of PATA devices still out there so having a PATA port on the mobo is very handy. I never understood these zealots who think that merely having a legacy port on their new motherboard somehow contaminates it. If you don't have any devices that use it, shut it off. Who knows, someday you might end up with one.

Re: Will the Serial Console Ever Die? (1)

LinuxIsGarbage (1658307) | more than 4 years ago | (#31302262)

Floppies STILL aren't IDE/PATA. Ever notice how they use a different pin count (34 vs 40), and are configured in the BIOS separately? []

Re: Will the Serial Console Ever Die? (1)

Megaweapon (25185) | more than 4 years ago | (#31301900)

I mean does ANYONE ever use a floppy disk anymore?

For kicks I just hit Servers Direct, and some, maybe most, of the server still offer the option of a 1.44" drive (presumably plugged into the motherboard). I'd hope these days a big honking server mobo would at least support booting from USB key. Certainly seems like a waste these days to be able to buy an 8U box, 3X redundant power supplies, dual or quad Xeon class CPUs, and they're still wasting space for a damn floppy cable mount on the motherboard.

Re: Will the Serial Console Ever Die? (2, Insightful)

c0mpliant (1516433) | more than 4 years ago | (#31301950)

Unfortunately yes. In my workplace we still use floppy disks and other legacy devices because other institutions also still use them.

Processes and systems that were setup 20 years ago still exist and when there is a system setup to handle something across an industry, in the example I'm thinking of its banking related, to get that changed across every company, institution and outlet take not only large amount of capital invest in the new hardware and software, but first agreement of the new standard, and then training after everything is done and then usually also changing large amounts of code that have been setup in each company.

Just because we in IT can see better ways to do things, doesn't mean that management can have the foresight to actually implement it and see it through. And usually they have a point, by the time we have everything implemented and up and running, there could/would be a better way of doing it again!

Re: Will the Serial Console Ever Die? (1)

c_forq (924234) | more than 4 years ago | (#31301990)

Yes, unfortunately. Where I work there is a plasma burning table that has no network interface. We have fiber-optic to all of our other machines but for that table the only option is a floppy disc. This is a concern as floppy's become more scarce, as once a disk goes out to the warehouse we do not let it back into the office (they get very dirty very quickly and jam up the office floppy drives).

Re: Will the Serial Console Ever Die? (1)

deniable (76198) | more than 4 years ago | (#31302050)

I've never seen an IDE floppy. There are still IDE optical drives around and a lot of surplus IDE hard drives, but floppies were always their own special interface. Hint: vendors now refer to IDE as PATA.

Re: Will the Serial Console Ever Die? (1)

adolf (21054) | more than 4 years ago | (#31302234)

I happen to own an IDE floppy drive in the form of an LS-120 [] , and it worked fine last time I used it. Other variations of that drive had SCSI, parallel, or USB interfaces.

My current floppy drive (read: the last one I'll ever buy) is a USB device made by NEC. It, too, just works.

Re: Will the Serial Console Ever Die? (1)

deniable (76198) | more than 4 years ago | (#31302358)

Good point, I forgot the LS-120, and yeah, I use a USB drive if I ever need to read floppies. Mine is a combo floppy/memory card reader.

Re: Will the Serial Console Ever Die? (3, Funny)

oldhack (1037484) | more than 4 years ago | (#31302058)

Yes, they filter dust in my desktop machines.

Web Interface (2, Informative)

DarkTitan_X (905442) | more than 4 years ago | (#31301844)

Most of the newer switches, routers, multiplexers and any other device with a serial port for a terminal interface I've had the pleasure of configuring had a web interface. I'd say that's the direction manufacturers are headed and is the next logical step.

Re:Web Interface (2, Insightful)

hedwards (940851) | more than 4 years ago | (#31302026)

I might be missing something, but that's not an adequate substitution. The point of a serial console is for when something goes wrong and for some reason the configuration is broken. In situations like that a web interface doesn't do you a damned bit of good because you can't access the box directly via the internet. Watchdog hardware or remote reboot hardware can get the box back up, but without a good serial console you're not likely to be able to fix the problem without being there.

With a serial console you can have one box hooked up to quite a few other ones to deal with that problem indirectly. It's not ever going to be phased out in the manner you're suggesting, it will however at some point be replaced with something that works in a similar fashion. But the real question is how long until the bios and early functions of the computer be access via some other sort of connection.

Re:Web Interface (3, Informative)

jonwil (467024) | more than 4 years ago | (#31302048)

As someone who has worked with Cisco routers running IOS, I can tell you that there are plenty of situations where a console cable (which plugs into a serial port) is essential.

Re:Web Interface (1)

deniable (76198) | more than 4 years ago | (#31302066)

Web interfaces are all well and good unless you're having to configure IP on the device. Fallback to DHCP is good, unless you have a device that somebody's configured wrong and needs to be corrected.

Simplicity (4, Insightful)

ak_hepcat (468765) | more than 4 years ago | (#31301856)

It calls out to you.

The great thing about a serial console is that it doesn't take long to figure it out. And you only need 3 wires to get there.
Another nice thing about it is that it's point-to-point, so you don't have to worry about your signals getting lost.

Heck, you can create a serial interface from discrete components if you're really into fun.

So use your serial console for what it's intended to be used for: emergencies and initial configurations.

Re:Simplicity (1)

pspahn (1175617) | more than 4 years ago | (#31301884)

Heck, you can create a serial interface from discrete components if you're really into fun.

Sounds pretty fun to me.

Re:Simplicity (5, Informative)

darronb (217897) | more than 4 years ago | (#31302056)

Simplicity really is the key.

Just a few days ago I hacked together a 9600 baud serial output in like an hour to help me debug an embedded microcontroller design using only a single IO pin and a crude spin-delay based bit-bang function. It worked great, and I found the trouble.

There's no way you could add something like USB nearly as easily. FTDI makes some great chips / cables, but at the microcontroller it's still TTL-level serial IO.

Plenty of microcontrollers have lots of extra serial IO ports. Many are adding USB ports as well, but it takes an absolutely stupid amount of firmware to make USB work.

There are several microcontrollers I can do USB for, since I've done it before. However, it takes weeks of work to implement USB the first time on any new microcontroller. It's usually really prone to bugs, too. USB is just too complex for the simple dumb pipes that most embedded developers need. On top of that... most of the time the micro vendor's USB firmware examples just barely work, and aren't designed very well so they're very hard to modularize and include in another design.

Re:Simplicity (2, Insightful)

glyn.phillips (826462) | more than 4 years ago | (#31302124)

Another feature is software simplicity. This may not be an issue for the laptop, but it is an issue for the embedded system. Or it can be during development.

USB is a complex protocol which requires a fair amount of code and data structures to support. A serial port on the other hand requires less than a page of code (in it's most simple form). The result is that when a system crashes, a serial port has a much better chance of being operational than a USB interface. Many systems with serial ports are designed so that a break signal on the line will interrupt the processor from whatever it's doing and send it directly to the debugger. When you can examine the entrails it is much easier to divine the cause.

Of course it is possible to design a bit of hardware which looks like a USB serial port adapter to a laptop and a serial port to the embedded system. Even better would be a new USB interface which gives full access to system memory and processor state.

The serial connection (1, Interesting)

dyfet (154716) | more than 4 years ago | (#31301862)

First there are plenty of USB-serial converters, so the lack of old-school DB9 serial ports on laptops is entirely a non-issue.

Also, some devices I see are already offering serial console access over USB, basically simulating I imagine what a USB-serial converter looks like, so if you plug into the device, you get USB-serial console access without the need of converting to serial and then having a serial cable. Also, USB carried serial consoles can operate at higher speeds than traditional rs232 cabling allowed, which should address firmware updates, as well as offering other means, such as USB access to real or simulated filesystems over the same USB port as a multi-device hub.

So the short answer, I see, is that the serial console is not "going away", but rather is slowly migrating to USB.

Re:The serial connection (1)

acoustix (123925) | more than 4 years ago | (#31302182)

First there are plenty of USB-serial converters, so the lack of old-school DB9 serial ports on laptops is entirely a non-issue..

While this is true, I have yet to find a USB-serial converter that passes the Esc key command. This is an extremely important feature, especially if you ever need to break into a switch or router to recover an account password.

Re:The serial connection (0)

Anonymous Coward | more than 4 years ago | (#31302314)

That's nothing to do with the USB-serial adapter, and probably nothing to do with the device driver.

It's almost certainly because your terminal emulator is a piece of crap.

Re:The serial connection (1)

X0563511 (793323) | more than 4 years ago | (#31302300)


USB-Serial is just about useless for _many_ things. It works for consumer shit, but you tend to have problems when you work away from consumer level cruft. The best part is there's no easy way to know if it works or not. Some times it sorta-works. Other times it just plain doesn't.

Serial replacement for consoles: Serial-over-USB (0)

davidgay (569650) | more than 4 years ago | (#31301864)

A lot less annoying than serial, rather strangely.

David Gay

It just works (5, Insightful)

mtmra70 (964928) | more than 4 years ago | (#31301870)

I upload firmware and program various devices at work via USB or TCP/IP - and it is great because the connections are fast. However, when something goes very wrong with the devices, the RS232 port always works. Also, being able to get serial data just by listening to a couple pins is far easier than trying to deal with USB connections/drivers you have no clue about.

When it comes down to it, serial works, its easy and it's a life saver.

Re:It just works (2, Interesting)

emt377 (610337) | more than 4 years ago | (#31302036)

A lot of boards these days are populated with FTDI FT232 chips or comparable. [] Usually using a separate 'console' USB port separate from the host/device ports provided in addition. Pretty much every desktop system comes with FT232 drivers, so all that's needed is a cable, or possibly an INF file or similar if they use a nonstandard MID/PID. Eventually we'll probably see these on-chip on SoC devices that already have USB support. But RS232E is quite practical and easy to troubleshoot, and I don't know any embedded engineer or board designer who doesn't know how to wire that up. I agree TFTP and flashing from a USB stick is nice, but a console is great to figure out why that might be failing, to see kernel panics, etc. Of course, a JTAG adapter and debugger that can talk to it is a huge time saver when it comes to actually fixing boot loader, flashing, or kernel bugs...

Re:It just works (3, Insightful)

0100010001010011 (652467) | more than 4 years ago | (#31302076)

My SheevaPlug [] has a mini-USB connector on it. It's near impossible to brick. I even did a dd /dev/zero to the entire flash memory and was still able to get to the JTAG interface with a USB cable to my MacBookPro.

"Serial" shouldn't go away, but the massive plug should.

New Cisco devices are going to USB console (1)

ErikTheRed (162431) | more than 4 years ago | (#31301878)

The latest-generation Cisco devices are switching to USB for console communications. So it's starting to happen...

Re:New Cisco devices are going to USB console (1, Informative)

Anonymous Coward | more than 4 years ago | (#31301998)

The cisco usb is actually just a usb to serial converter into the serial port of their chip. So, it really only solves the configuration and cabling part of the problem. You're still limited to serial baud rates.

Only one use left (0)

mcpherrinm (1728748) | more than 4 years ago | (#31301888)

Consumers have long since stopped using serial cables in favour of USB. The only real place that they still exist is to get a serial console on servers in a datacenter. The OP suggests that it might be replaced by USB here too, but this is where I disagree. For that sort of task, network-based services are becoming more common. Ethernet is cheap and easy to deploy, and not that difficult to implement in hardware. Though there'd be nothing to stop a server manufacturer from just building a serial-to-usb converter into their hardware so you get the traditional serial interfaces but using USB. The serial cable isn't dead yet.

Re:Only one use left (2, Insightful)

hedwards (940851) | more than 4 years ago | (#31302042)

Have you any idea how insecure it is to access the bios via ethernet? It's hard enough keeping things secured when a box is internet connected, but allowing people to set the bios options and early boot process stuff via ethernet is absolutely insane and an incredibly warm invitation to crackers. And if it doesn't allow you to do that then it's more or less useless as a replacement for a serial console anyways.

Re:Only one use left (1, Funny)

amorsen (7485) | more than 4 years ago | (#31302254)

Those crossover ethernet cables are way less secure than serial cables! Like, as soon as you plug one end into your laptop and the other end into the server, the server is going to get 7 different trojans! In the BIOS!


Re:Only one use left (2, Interesting)

darronb (217897) | more than 4 years ago | (#31302176)

Well, I disagree about that being the only place. Serial ports are absolutely huge in the embedded world. A large number of consumer devices also use serial internally, and maybe convert to USB right at the edge of the box.

Networking brings up an interesting point. I actually prefer to add Ethernet to an embedded design over USB. It's actually easier, if you can believe that bull****. It's also massively more flexible and quite a bit faster.

Many TCP/IP stacks can be ported to a new platform by simply implementing a read, a write, and a status function to talk to your specific MAC.

USB is usually a horrible kludge taking some vendor's usb-to-serial or mass-storage example code and hacking the crap out of it until it works. The USB module registers are so different from vendor to vendor, etc.

At the PC level, it's different. There are some standards there. Even there, it usually takes custom device driver work to get a new device working... something that Microsoft should be totally ashamed about. They really should have provided something like libusb on Linux.

To summarize, USB is a horrible horrible bus for the thousands of smaller embeddded shops out there. It requires dealing with incredibly poor quality vendor example code, and worst of all you have to find someone who can write you a Windows device driver. Well... unless you're lucky enough to know how to do that yourself. I can, but it's such a pain in the ass that I'd much rather use Ethernet... which doesn't require a stupid driver on every OS you want to use it with.

No. (5, Funny)

Dr. Evil (3501) | more than 4 years ago | (#31301890)

It will never die. It will be around forever. Technicians, thousands of years from now will have to interface with wireless psychic rs232 adapters so as to configure their Cisco hyperdrives.

UARTs are cheap... (2, Informative)

Anonymous Coward | more than 4 years ago | (#31301898)

As an embedded device engineer, I love good old UARTs. They are very small cores to add to an FPGA design, simple to write a driver for, and fast enough for most simple debug applications.

Trying that with a USB core is not an easy prospect. And they arent *that* slow. The free UARTlite IP core from Xilinx can run up to 921,600.. plenty fast for most things embedded...

As long as (4, Interesting)

phantomfive (622387) | more than 4 years ago | (#31301902)

It will exist as long as it is useful. Right now, people are still finding it useful, therefore it still exists. You still see ISA ports around sometimes.

Serial? (1)

SIR_Taco (467460) | more than 4 years ago | (#31301912)

Com on, give the serial port a break. The future may not be bright, baud I would bet it will still play its port.

Re:Serial? (0)

Anonymous Coward | more than 4 years ago | (#31302214)

Boo *Throws rotten tomato*

RTS, CTS, DTR, X-On, X-Off, I love that stuff! (1, Insightful)

Anonymous Coward | more than 4 years ago | (#31301918)

Let's keep it around forever. You kids are going too fast anyway!

You need to take time to ponder the deeper questions, like in-band or out-of-band?

RS232 port utility (5, Informative)

Announcer (816755) | more than 4 years ago | (#31301922)

I work for a small electronics manufacturing company, []
and we make a number of devices that use the serial port. In recent years, we had to start including USB-serial adapters with every device for the very reason mentioned: Many newer computers simply do not have RS232 ports anymore.

The RS232 port is a very convenient way to connect with a number of peripheral devices that don't need much bandwidth. In most cases, 9600 BPS is plenty. You also have the "handshake" lines which can be used to toggle an external device on or off. We use it to drive an LED and an opto-isolator to key a ham radio transmitter, among other things.

As long as there are low-bandwidth, human-interface devices, there will still be SOME use and purpose for the RS232 port.

Re:RS232 port utility (2, Interesting)

usul294 (1163169) | more than 4 years ago | (#31302310)

right on, two recent projects I've done, one my senior design project, and my first professional job had me using RS-232 to connect a laptop to an embedded system. If the host machine only needs to see a single floating point number a couple times a second, RS-232 is plenty fast enough, and is much less time consuming from a design standpoint than say a TCP/IP connection.

Xserve have a serial port (1)

yuhong (1378501) | more than 4 years ago | (#31301934)

I wonder what was Steve Jobs' reaction when he was told that the Xserve is going to have a serial port, considered "legacy" by Apple since the iMac in 1998.

Easy to design in (5, Informative)

jimmyswimmy (749153) | more than 4 years ago | (#31301946)

I still design lots of equipment with serial interfaces inside. It is much easier to connect to a low-end microcontroller which may barely have even a single UART. And even for a higher-end processor, it's so much easier to build the interface. Developing a USB interface requires a pretty detailed understanding of USB - selecting endpoints, which transfer protocol to use, etc - so there's a big software investment and often a significant additional hardware investment to implement a USB interface. Serial is often damn close to free, so easy that it's a no-brainer to put in. And for ethernet devices like switches I can't imagine why anyone would want to bother with a USB interface when you already have 8/16/48 copies of an ethernet interface available, just plop down yet another copy of the ethernet PHY design and make that your console interface.

Point is - serial's EASY to give you, so you're gonna keep getting it for a while.

Separate Good Functionality from old Hardware (4, Interesting)

CajunArson (465943) | more than 4 years ago | (#31301948)

I actually posted an Ask-Slashdot [] about running a headless Linux Box that didn't have any serial ports... my question was about what happened in the 5% of cases where I couldn't SSH to the box (like if a kernel upgrade goes south). The basic answer was that I still needed a serial terminal. Oh, I know that USB can be used as a substitute, but the problem was that USB required a booted & functional kernel with a working USB stack to emulate the serial line. I recently saw a similar discussion in comments about how bad the old-school serial terminal code that is still in the Linux kernel is. Many people incorrectly thought the poster was saying that Linux shouldn't have a command line interface, which was completely wrong. The poster instead raised the (excellent) point that complicated and buggy software emulating long-obsolete device interfaces may not be good for the Kernel (CLI is NOT the same as a terminal interface).

Are there damn good reasons why RS-232 serial ports should be dropped from modern hardware? Hell yes, not the least of which is a 3-15 volt swing signalling protocol is an invitation to fry the low-voltage electronics on modern systems. However, the CONCEPT of having a box that does not require any type of graphics, or even a working network interface, is still very useful. So... what are the better technologies to accomplish the same goal without having to rely on antiquated hardware implementations?

robustness of connection (0)

Anonymous Coward | more than 4 years ago | (#31301952)

USB connections can be accidentally knocked lose, RS-232 can't if the screws were tightened properly.

Re:robustness of connection (1)

deniable (76198) | more than 4 years ago | (#31302086)

USB connections slip free if someone trips over the cable, RS-232 rips the port out of the box if the screws were tightened properly. Argument goes both ways.

It took me a while to get this... (1)

SECProto (790283) | more than 4 years ago | (#31301958)

It took me a while to get this ... then I realized you were talking about a different kind of "console" than xbox, nintendo, or playstation.

Re:It took me a while to get this... (2, Funny)

deniable (76198) | more than 4 years ago | (#31302102)

Wait till you learn about DLC []

Options? (0)

Anonymous Coward | more than 4 years ago | (#31301962)

The RS-232 serial Port means you do not have to download and install drivers. Since there is no USB standard device ( And there could be) the equipment maker has few choices. Write and qualify a USB Driver ( for each OS), put a USB to serial converter chip in and use is drivers, or try to be a HID Device. Adding a USB Logo means USB Group testing of Hardware and software not cheap either.
Or you can drop in an RS-232 Port and let the user Add in a serial port Card or dongle. That is why they are still there.

BTW ASUS still has a comport on some of it Mother boards.

Re:Options? (1)

Tablizer (95088) | more than 4 years ago | (#31302164)

If enough hardware vendors start using USB instead, then some sort of standard or de-facto standard chip and interface set will eventually emerge such that software drivers etc. are no necessary. But it's kind of a chicken-or-egg dilemma because the first movers may be at a disadvantage.

No, never, nunca! (1)

bradgoodman (964302) | more than 4 years ago | (#31301968)

As previously stated - there are exceptions, such as using USB - granted, all this is doing is putting the USB-to-Serial converter *inside* the piece of hardware - as your PC/laptop is treating it as such - and giving you "serial" access to the device.

As for the "greater" question, as will Ethernet/Network/Web interfaces ever surpass it - I will contend, the answer is no - or not any time vaugley soon.

I used to own a company that made NAS appliances - back many many years ago. When you had a "plug-and-play" device going onto a network, there were too many things that could go wrong. The question always came up: What happens if I plug the device in, and can't find it on the network? Sort answer was usualy: RMA. We started building a little LCD display console into our devices, which reduced the RMA rate to [near] zero. This wasn't even in cases where it was "our fault" - but even for stupid things, like the DHCP server was down, or address pool was exhausted, etc.

Many years later, weither I am plugging a terminal server, network power bar, switch, router, or even a laser printer onto the network - the same question comes up - what happens if you do eveything right (so you think) and the damn device doesn't show up? Maybe its because some a**hole got in there and set it to some bizarre static IP address - or whatever - how do you recover? You'll always need some sort of direct access in a time of despariation, and BTW, serial is a whole lot cheaper than an LCD display console.

No (5, Informative)

dindi (78034) | more than 4 years ago | (#31301992)

Serial is cheap, simple, works really well, and you can hook up 15+ year old equipment to it with no problem.

Is it slow? Not really, but firmware updates should be through TFTP or HTTP by now anyways for larger files.

Complicated wiring? RX-TX TX-RX, common ground.

Also RS-232 has many brothers and sisters like:
RS-422 (a high-speed system similar to RS-232 but with differential signaling)
RS-423 (a high-speed system similar to RS-422 but with unbalanced signaling)
RS-449 (a functional and mechanical interface that used RS-422 and RS-423 signals - it never caught on like RS-232 and was withdrawn by the EIA)
RS-485 (a descendant of RS-422 that can be used as a bus in multidrop configurations)

On the USB console: yeah, you can have a USB console. Most like there will be a FTDI chip, which will make your USB into a serial connection. Want an example? Arduino.....

By the way, the post is kinda mis-worded.... USB is a serial bus, so a USB console is technically a SERIAL console :)

Re:No (1)

AK Marc (707885) | more than 4 years ago | (#31302166)

RS-485 (a descendant of RS-422 that can be used as a bus in multidrop configurations)

I never heard of it being used as that, but it's always used when the distance is long. I've even deployed 232 to 485 to 232 setups to get RS-232 gear separated but 100+ feet to work. But usually, it's ODU gear with an RS-485 port because they expect to be installed a long distance from any controlling device. Then it's just a single indoor adapter to plug it into a PC. Where's my serial port on my PC that's selectable between all the serial standards like you get on the nice terminal servers?

Re:No (0)

Anonymous Coward | more than 4 years ago | (#31302236)

Is it slow? Not really, but firmware updates should be through TFTP or HTTP by now anyways for larger files.

Really, it all depends. The big problem is that it uses RS232. I've used serial UART at 20Mbps on embedded microprocessors. I'm not sure why this couldn't be applied to these systems to increase the speed beyond the current 115Kbps.

first po5t (-1, Redundant)

Anonymous Coward | more than 4 years ago | (#31302000)

[samag.comn] in the for a momeRnt and

No, because it requires no configuration (1, Insightful)

Anonymous Coward | more than 4 years ago | (#31302002)

you can boot and start listening for commands on a serial port without
any ip addresses or netmasks or gateways or any configuration
whatsoever. That's the key.

Serial is still alive and kicking... (0)

Anonymous Coward | more than 4 years ago | (#31302018)

Not so much in the standard computer world, but in broadcasting for example, many of the automation systems rely on plain old serial connections to fire off various components. How much bandwidth do you really need to send a simple command or two? If you are sending small short packets with byte sizes you can count on your fingers... is USB or TCP really any faster?

Put another way, where space isn't the primary concern, serial is dirt cheap, simple to use and configure, has fewer restrictions on cable length, and wire grade, and is more than adequate for many purposes... If it ain't broke, don't fix it.

That said... once a certain level of complexity is reached, ethernet, USB etc. become much more attractive.

Offshore Survey Industry (5, Interesting)

ss_teven (569013) | more than 4 years ago | (#31302096)

I work in the offshore survey industry (oil/gas industry), and 95% of products to date still come with serial ports. They are critical for our purposes, and onboard com ports are a must for timing critical jobs such as multibeam bathymetric surveys.

Current project im working on we are using Moxa multiport serial boards w/ 32 serial ports on this pc with around 25 currently inuse for IO. (Historically used Digi boards but they were awful for timing (relatively!), 30ms delay compared to the near 0ms on the Moxa units.)

Simple to use, easily available, and cheap. Almost all the devices I work with use standard parity/stop bits etc, just varying baud rates, which is easy enough to remember.

Too late! (4, Funny)

macraig (621737) | more than 4 years ago | (#31302100)

I attended its funeral yesterday. It was an open-casket ceremony, and people just couldn't seem to resist fingering the deceased. Sadly it didn't respond.

USB console (2, Informative)

tftp (111690) | more than 4 years ago | (#31302120)

Is there any sign on the horizon of a USB console connection?

There is no standard USB device class for serial adapters. There is communications device class, but it is huge and doesn't really help. So FTDI and Cygnal and others have to write their own drivers for tens of OSes and architectures. If you walk up to a device with a laptop and a USB cable, chances are that your laptop doesn't have a proper driver. To make things worse, many USB-Serial adapters have to use their own VID/PID/REV identifiers, and that makes it even harder to recognize the device. Class-compliant devices would "just work" like a USB drive does, or a mouse.

There is also no standard API in OSes to talk to *modern* serial devices. USB serial devices are emulated into a virtual COM port.

USB is a poor choice - Ethernet works pretty well (4, Interesting)

Foredecker (161844) | more than 4 years ago | (#31302142)

I understand what you are saying: RS232 ports suck for any number of reasons.

But there are a few why it is still often used.

First, it has been ubiquitous for 20 to 30 years. When I started my first development job in 1982 - everything talked to everything else via RS-232. Back then 9600 baud was considered fast. At 8 bits per character with no parity and one stop bit, 9600 baud could paint a screen with characters in one second. Yes, we thought that was fast. Things got better as baud rates improved - but RS-232 remained everywhere - it was the one constant universal interface. Even though it is incredible antiqued, it is still in many PCs.

Second, RS-232 (and its many cousins like RS-422) are very, very easy to use in software. The simplest I/O can be done in a few lines of code. Its easy to put RS-232 code right in firmware. This makes it easy to write bootstrapers, boot consoles, debug consoles etc.

USB would be a poor choice for a replacement. The reason is that it isnt peer to peer - it is a master/slave architecture. There is always one master -usually a PC, and one or more slaves (keyboards, mice, printers, scanners, cable modems, disk drives, storage keys, cameras etc).

It requires a special cable to make to client USB devices talk to each other. This cable has a small do-dad that looks like a master to both ends. This works ok, but it requires special knowledge of this USB end point to work correctly. Note, Windows began to support this in Vista for migration. Its called Windows Easy Transfer/a>.. There is a version for XP too ( [] downloadable/a>). It actually works very well, but the cables were not cheap. Note that the cables really are not cables - but a dual-headed master USB controller with two ports - it just looks like a cable with a lump in the middle - [] Belkin sells one for $40 [] .

LLike a few other posters have said - USB is much more complex to use in software than simple RS-232. Ive written code for it and I find it more complex than Ethernet at the MAC level.

I think Ethernet is the real replacement. A little TFT or Telnet server / client is really trivial to write. This can (and often has been done) in firmware. For example, most (all?) home Ethernet and wireless routers dont have a serial port. Their management is over Ethernet - works great.


RS232 still very cool... (0)

Anonymous Coward | more than 4 years ago | (#31302152)

RS232 rocks,and will always rock.

I actually designed a converter that turns an 9-pin serial port into 6 USB ports plus an ethernet port. Check it out:!/album.php?aid=2022767&id=1462922757

they need use SD card / usb keys for firmware / co (1)

Joe The Dragon (967727) | more than 4 years ago | (#31302180)

they need to use SD card / usb keys for firmware / base / fallback config. just put in a small eprom with a base boot code that can reed a usb key to upload the firmware. The SAM system is build like this and is a lot easier to update then burning new eprom for full code updates.

Probably not... (1)

bbourqu (690731) | more than 4 years ago | (#31302212)

Probably not. Serial is s$#t simple and utterly reliable in dire circumstances. I'm a network engineer at a large university and have spent the last 3 years setting up an "out-of-band" network that includes serial access to all of our network devices. The bit rates can be increased to upload firmware when necessary. Cabling is straightforward and follows the old DTE/DCE standards. The new devices that have USB Type A physical interfaces that I have come across still RS-232 signaling, requiring special cables. We recently had to make a batch of these custom cables to accommodate access to serial ports on new blade chassis SAN equipment. Like it or not, RS-232 serial ports will be around for a good, long while.

Pry my DB9 RS232 cables from my cold dead hands (0)

Anonymous Coward | more than 4 years ago | (#31302232)

I designed a serial to USB/Ethernet adapter so legacy serial ports can upconvert to either standard. Underneath all these other technologies, is and will always be a serial port.

Check it out []

Ever tried programming USB? (2, Insightful)

SharpFang (651121) | more than 4 years ago | (#31302238)

RS232 is easy to program. If it's a switch without OS or some other embedded device, RS232 is the easiest and fastest way.
Sure on the PC side there are the problems of baud, parity and so on. Thing is on the device side you can get a working bidi buffered transmission within 30 lines of assembler (100-200 if you have no UART and need to push each bit yourself). Writing equivalent of "hello world" over USB becomes kilobytes. And if you go into a web interface, you quickly lose enthusiasm as you realize on top of CGI you need to write the web server, the TCP stack, the IP stack, and if you're unlucky, the Ethernet protocol stack (in VHDL) as well.

On top of that, a thousand things can go wrong in writing USB or Ethernet or whatever. RS232 is rugged, fault-proof, it works from moment zero. You will be able to communicate with bootloader which has no idea what ethernet is, you will be able to diagnose faults when 90% of essential peripherials are fried, and if the cable goes loose, just move it around a bit and the connection will be back, no timeouts, no disconnects, no "intelligence" to get in your way.

And if you open various devices that use USB instead of serial, you will find a neat little FDDI, Profilic or such chip connected to the USB interface. The devices really connect over RS232. They just have the "RS232 over USB dongle" built in.

What will we do with all the US Robotics Couriers? (4, Interesting)

rcpitt (711863) | more than 4 years ago | (#31302272)

Telus - local ILEC - is installing ~$100k worth of hardware in all the local SAC boxes to allow them to run TV over the local loop at 15Mbps.

Guess what every SAC box has strapped to the back of the equipment rack - a US Robotics full-size (about 12"x7"x1") Courier modem!

Damned if I know where they're getting them from - but there they are...

Actually quite useful for simple hardware hacks (1)

Richard_J_N (631241) | more than 4 years ago | (#31302294)

If you exclude the TxD and RxD (and Ground) lines, there are still 6 others, which are trivial to interface to. YOu get 4 inputs and 2 outputs, to which you can connect switches and LEDs directly. Then use setserial/statserial to control/monitor the logic levels. This is actually quite useful sometimes.

I hope not! (1)

sjames (1099) | more than 4 years ago | (#31302304)

The great thing about a serial port is it's simplicity from a programming standpoint. Since console access is needed for diagnostics (that is, something is already wrong), the less it depends on, the better.

Most of the problems can be fixed by having vendors not all use different and OH-SO-SPECIAL pinouts for the serial connection and a dirt cheap USB Serial port for the laptop.

Baud rates, parity? (1)

David Gerard (12369) | more than 4 years ago | (#31302316)

I can't recall the last time I saw a serial port that wouldn't accept 9600 8-N-1. Not in a couple of decades.

It enforces a management design constraint (4, Interesting)

narnian (9597) | more than 4 years ago | (#31302338)

With the increasing complexity of network devices - switches, routers, load-balancers, firewalls, the expectancy of a functional terminal console puts a good design constraint on system developers. If they have to provide the ability within a 80x24 terminal funtionality to configure, operate and maintain a such a device it is a good thing. A good management is useful in providing an overview of the configuration and helps provide linkage to the management of components.

A serial terminal console is good because:-

* It enforces the designer to limit the presentation of management information to the 80x24 screen (possibly using pages), and often with a 9600bps data rate. My view is if they can't do it properly in a console they have not though well enough about management. Too often GUIs for management tend to hide important configuration parameters away.
* A terminal console allows easy copy-and-paste and script munging of configurations to ensure consistent deployment. GUIs don't allow such duplication of configurations very well.
* It allows simple out of band management through the use of a terminal server connecting multiple consoles. Such a simple management connection provides am always available management window in a network down situation. (Assuming this is deployed properly). You can also manage the risk well if management can ONLY be done by serial (preventing the management network inadvertently being connected to a production network.
* While standarardisation of the physical port (male or female DB9 or RJ45) and host type (DTE or DCE) and even hardware handshaking is right royal pain. At least it is usual possible to determine it after a minimum number of tries. But essential it is pretty straightforward to implement.
* While a USB connection sounds good, I would only prefer it if it was guaranteed to be a zero driver installation.

Newer Cisco gear... (0)

Anonymous Coward | more than 4 years ago | (#31302350)

...has standard serial console ports, along with a USB port that acts as a built-in USB-to-serial adapter. No serial port on your laptop required. And since most Cisco routers now keep the IOS on a CompactFlash card, you can stick the card in a CF reader on your PC to copy an IOS image to it (the days of doing an IOS upgrade over xmodem on serial are loooooooong gone).

You young whippersnappers and your newfangled... (2, Funny)

ameline (771895) | more than 4 years ago | (#31302362)

You young whippersnapers and your newfangled serial consoles.

Back when men were men, this is what a manly console looked like; []

serial on iPods (0)

Anonymous Coward | more than 4 years ago | (#31302370)

It's not widely known but iPods/iPhone have a serial port on their docking connector.

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