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Will the Serial Console Ever Die?

Posted by kdawson on from the can-you-say-are-ess-two-three-two dept.

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?"

31 of 460 comments (clear)

  1. You can buy a serial-to-usb converter for $15 by tomhudson · · Score: 4, Informative

    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).

    1. Re:You can buy a serial-to-usb converter for $15 by Anonymous Coward · · Score: 5, Informative

      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.

    2. Re:You can buy a serial-to-usb converter for $15 by transporter_ii · · Score: 4, Informative

      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.

      --
      Doctors destroy health, lawyers destroy justice, universities destroy knowledge, religion destroys spirituality
    3. Re:You can buy a serial-to-usb converter for $15 by russotto · · Score: 5, Informative

      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.

    4. Re:You can buy a serial-to-usb converter for $15 by Camel+Pilot · · Score: 4, Informative

      Right you are.... especially things like port powered 232 to 485 converter. Spent a half a day trying to get one to work until I measured the voltage on the handshake lines it was using for power - 3.5 volts which was a 1/10 volt lower than required by the converter.

    5. Re:You can buy a serial-to-usb converter for $15 by Sponge+Bath · · Score: 5, Informative

      That is defective design. Receive sensitivity for RS-232 is +/-3V so the signal is within spec. There are plenty of RS232 and RS485 devices that work off 3.3V using integrated charge pumps, and this device requires 3.6?. Double fail! I bet you were pissed off when you figured this out ;-)

    6. Re:You can buy a serial-to-usb converter for $15 by Hal_Porter · · Score: 2, Informative

      They can a bit - most of them suppport higher baud rates like 230, 460 or even 920 kbaud instead of 115. If you're flashing something from a PC that makes a difference.

      --
      echo -e 'global _start\n _start:\n mov eax, 2\n int 80h\n jmp _start' > a.asm; nasm a.asm -f elf; ld a.o -o a;
    7. Re:You can buy a serial-to-usb converter for $15 by dumb_jedi · · Score: 3, Informative

      Well, as a Electrial Engineer who designs equipment that have a serial console, I think I give you several reasons that the serial console will be round for some years yet.

      First, legacy. Most professional routers have come with a serial management console since ever. So anyone who's been trained to manage these devices use serial consoles for that. Of course, by being an IP equipment, you can manage them by accessing the same console using telnet, and you can upgrade their firmware using that console too. A USB to serial converter is a basic tool for anyone managing these type of routers

      Second, design. In a microcontroller, one of the simplest devices you can use is the serial port. A lot of bootloaders for embedded devices (U-Boot, Redboot, CFE) usually start with a banner on the serial console even before configuring the RAM controller on the CPU, so you know your board is running and you can output valuable error messages very early on the boot processes. Other devices, even a true USB console, need much more complex drivers that are loaded later on the boot process or need more configuration options than a simple "115,8n1" somewhere on the manual.

      Most domestic routers don't have a serial port. Well, they have, but you can't access them unless you open the case, the bottom line is that domestic users aren't even aware their wifi router have a serial port, much less that they have to use it. How often you need to unbrick your wifi router if you don't load custom firmware on it ? My guess is never.
      Third is that it doesn't make a difference, as others have pointed out, if the equipment uses a USB to serial conververter, as the serial device will usually be limited to 115 kbps, even if your serial interface can transmit up to 12 mbps. Only CPUs with USB devices on them will benefit from a faster interface. The iMX line of processors from Freescale is one of them.

  2. Web Interface by DarkTitan_X · · Score: 2, Informative

    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.

    --
    ~Mike (Titan_X)
    1. Re:Web Interface by jonwil · · Score: 3, Informative

      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.

  3. Re:Serial Ports.. by unr3a1 · · Score: 4, Informative

    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...

  4. UARTs are cheap... by Anonymous Coward · · Score: 2, Informative

    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...

  5. Re:Serial Ports.. by Anonymous Coward · · Score: 2, Informative

    "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.

  6. RS232 port utility by Announcer · · Score: 5, Informative

    I work for a small electronics manufacturing company, http://www.westmountainradio.com/
    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.

    --
    Willie...
  7. Re:Serial Ports.. by interiot · · Score: 3, Informative

    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.

  8. Easy to design in by jimmyswimmy · · Score: 5, Informative

    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.

    --

    Just my $0.55 (US inflation, 1774-2008, for $0.02)
  9. No by dindi · · Score: 5, Informative

    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 :)

    1. Re:No by Antique+Geekmeister · · Score: 2, Informative

      Unfortunately, every untrained technician and their ill-trained supervisor gets these wrong. The flow control lines are not there for laughs: mis-handled, they lead to many unfortunate adventures, at the worst moments. I've had to deal with the errors when someone thought the way you did, failed to connect the flow control to anything, and wound up with jammed serial lines.

      The standard is published many places, such as http://www.zytrax.com/tech/layer_1/cables/tech_rs232.htm#db25. Even your "three wire description" has left something important out, that I've seen mis-wired: the third wire is _signal ground_, not "common ground". "Common ground" is when we share something interesting to talk about: it's an unfortunate choice of words for wiring.

  10. Re:New Cisco devices are going to USB console by Anonymous Coward · · Score: 1, Informative

    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.

  11. Re:Simplicity by darronb · · Score: 5, Informative

    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.

  12. USB console by tftp · · Score: 2, Informative

    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.

  13. Re:It should have been phased out... by Jhon · · Score: 4, Informative

    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.

  14. Re:Serial Ports.. by darkpixel2k · · Score: 5, Informative

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

    No, that little RJ45-looking jack labeled 'Console' on most newer Cisco and HP gear is actually for a serial to RJ45 cable...

    --
    There's no place like ::1 (I've completed my transition to IPv6)
  15. Re:The serial connection by Anonymous Coward · · Score: 1, Informative

    You mean DE9. DB9 would be a shell the size of a 25-pin serial connector (that's the "B" size) but with only 9 pins fitted.

  16. Re:RS232 is fee-free by Anonymous Coward · · Score: 1, Informative

    Mostly True FTDI will give you 8 PID number of there VID for free.
    You then edit the install and it says you. So for Linux
    Then for 400 dollars for a Verisign Number and 100 to Microsoft It will ID your equipment and Download from Microsoft update ( FTDI has an app note).

    Or you slap in a MAX232A and your done.

  17. Re:It should have been phased out... by Bester · · Score: 4, Informative

    Funny, I just walked around my ICU and everything is connected via ethernet. Monitors (philips), ventilators (dragers) and of course the computers (windows). Even the dialysis (prismaflex) machines hook via ethernet.

    The ultrasound has an ethernet cable attached as do the image intensifiers. The biochem lab also works over TCP.

    Certainly nothing major in the hospital that I work in uses serial connections.

    Maybe the older equipment used to use serial but given the amount of data shuttled around I don't think it would be feasible so use serial. Of course I can only draw experience from where I work, other hospitals may be different.

    Charles

  18. Re:It should have been phased out... by Anonymous Coward · · Score: 3, Informative

    I've been developing for the Atmel ATSAM3U chip, which uses the ARM Cortex-M3 core. Its development board has serial ports, but I can reprogram the chip entirely, from full eraase, with just the built-in USB port.

    When erased, the chip boots off an internal ROM. That ROM, if yo have a 12 MHz crystal hooked up, will activate the USB 2.0 Device port and make it look like a serial dongle. You talk to the thing via /dev/ttyUSB0 and download the program top flash through it. As a final step, you run a couple commands on it to switch the booting over to Flash. And you're done. If you want to erase the chip, there's an ERASE pin you pull down for 200 ms or so, and it's erased.

    The dev board adds another twist to it. It has an onboard NAND Flash chip, which uses the built-in ECC unit on the SAM3U. If the development board is running the demo code, then that NAND Flash will show up as a USB thumb drive when you plug the board into your computer. So you can read and write the NAND Flash from your computer as if the ARM wasn't there. The board ships with its source code, binaries, and data sheets on that NAND Flash, just to prove its point.

    This is where the future is going. RS-232/422/485 will become more and more niche oriented. Industrial apps that need more than 15 foot cables will still use serial ports.

    But I doubt it'll always be a requirement for embedded work, I've found that using an FT232 USB-to-serial chip is the way to go in my embedded designs. It pretty much replaces the RS-232 transceiver chip, and doesn't need charge pump capacitors or funny voltages. You never need a null-modem adapter or gender changer. You never have to wonder what baud rate/parity/whatever is needed; just set that in the FT232's EEPROM. The chip hooks directly to TTL serial port pins that all microprocessors use. You can even choose if you want handshaking or not, and the FT232 can even drive activity LEDs for you. A USB Mini-B or Micro-B connector is far easier to find a home for than a DB-9. What's not to like?

    I've been using serial ports for 25 years. I will NOT miss them.

  19. Re:RS232 is fee-free by timonak · · Score: 2, Informative

    Thats not 100% true. You can get a 16 PIDs from FTDI for free and use their programmer tool to replace their PID with yours. I did this for a biomedical device manufacturer we purchase equipment from. You still have to use their VID, and it takes a tiny bit of work to make the FTDI serial driver work with the new PID but its entirely doable.

  20. Forget Moore - what about Wirth's law? by fibrewire · · Score: 2, Informative

    "Software is getting slower more rapidly than hardware becomes faster." -Wirth

    Lets see - I'm building a UAV using RS-422 for fly-by-wire operation using a RTOS and embedded hardware. Do I want TCP/IP or USB buffers involved on servos that control its ability to stay in the air? I can only imagine getting a lecture from an engineer at Raytheon about keeping things simple.

    I wonder if someone will make a joke about selling Toyota Motor Corp a USB accelerator control...

  21. Re:It should have been phased out... by Sique · · Score: 2, Informative

    It is most often sufficient to delete the Serial Port in the Device Manager and then run a scan for new hardware.

    --
    .sig: Sique *sigh*
  22. Re:Serial Ports.. by Junta · · Score: 2, Informative

    Look carefully. Sure, most don't use DE9 as it is a huge connector, but they will have the pins required for RS-232 signalling. A popular choice is RJ-45 (with frustratingly varying pinouts, requiring multiple RJ45 to DB9 conversion cables for a heterogeneous environment). Some use a mechanically mini-usb port that is actually RS-232 (Nortel comes to mind). I've even seen some equipment that did RS-232 signalling over 3.5 MM jack. I've also seen a number of wacky one-off form factors, whatever they can do to save real-estate and at least get transmit, receive, and ground lines out (5 pins if hardware flow control is desired).

    --
    XML is like violence. If it doesn't solve the problem, use more.