Dell laptop serial port

[notquitehere188]

Is the serial port on dell laptop port replicators sufficiently fast for code uploading? we are finally getting a new laptop, but we dont want the slow uploads we got with a usb to serial converter. If not, can anybody reccomend a laptop manufacturer with native serial ports?

[Adam Richards]

Is the serial port on dell laptop port replicators sufficiently fast for code uploading? we are finally getting a new laptop, but we dont want the slow uploads we got with a usb to serial converter. If not, can anybody reccomend a laptop manufacturer with native serial ports?You do realize that the serial interface as a whole is considered "slow" compared to other interfaces used today (i.e. USB, Firewire), right?

[Greg Marra]

I am not certain, but I would speculate that any serial port built into a laptop would be a 'native serial port' since it would be built into the motherboard. It would actually be more expensive for the manufacturer to put a USB-serial adapter. If it was a USB-serial adapter, then you wouldn't be able to access it in the same way from the BIOS.

Is there much of a speed increase with a native serial port to a USB-serial adapter? It seems that the main bottleneck would be whatever baud rate the RC wants to talk to you at, and I have never heard of a USB-serial adapter that didn't support the standard array of baud rates.

To Adam's point, serial transfer rates are measured in baud. One baud is one bit per second. There are 8 bits in a byte. 20000 is the maximum the standard officially supports (http://en.wikipedia.org/wiki/Serial_port#Speed).

[double edit] I just noticed that you were talking about a Dell port replicator, not a Dell laptop. I have no idea, but I still don't think you're going to see any amazing speed increases[/double edit]

[Jay H 237]

Finding a new laptop with any serial port is going to be very limited. Most only have USB 2.0 and Firewire. The demand for serial devices isn't what it used to be although Dell and a few others still offer a serial port on some models, you're just not going to have much choice.

Using a built in serial port will be better than using a converter.

[IraJason]

Dell actually sells laptops with Serial Ports. The Latitude D510's that we have all have serial ports on them. The problem is, I just visited the Dell website, and they don't sell the D510's anymore. You'll have to check out the specs on some of the other laptops they have to see if they still have the option for Serial Ports.

Edit: It's quite possible they are still available on other dell laptops. The D510s that we bought are literally brand new.

[Alexa Stott]

I use a USB to Serial converter, and it takes a long time. It's not really that bad.

As it was mentioned above, it's really hard to find a laptop that comes with a serial port. I think IBM ThinkPads still have them, but I could be wrong.

So unless you want to buy an older laptop from somewhere, you will pretty much be stuck with using something like a USB to serial.

[Cai ZhongHan]

As it was mentioned above, it's really hard to find a laptop that comes with a serial port. I think IBM ThinkPads still have them, but I could be wrong.

Most, if not all current Thinkpads do not come with built-in serial ports. You will need a port replicator/dock to get the serial port.

[yongkimleng]

Most, if not all current Thinkpads do not come with built-in serial ports. You will need a port replicator/dock to get the serial port.

or grab a usb-serial dongle for about US$10+ :yikes:

[Eldarion]

or grab a usb-serial dongle for about US$10+ :yikes:

The problem with (most) USB-to-serial dongles is that the IFI loader dials down the speed so far that it can take 15 minutes or longer to download the code, versus less than 30 seconds on a normal serial port. It probably has something to do with how the loader negotiates the transfer speeds; I.E. the USB converter may have an intrinsic delay that throws the timing calculations off.

Seeing as the port replicator interfaces directly to the mainboard of the laptop over a high-speed bus, chances are it would be more like adding a daughterboard with a serial port and it might even be assigned IRQs and I/O addresses by the laptop's BIOS, in which case it should be indistinguishable from a normal serial port.

Just my $0.02. :)

[yongkimleng]

The problem with (most) USB-to-serial dongles is that the IFI loader dials down the speed so far that it can take 15 minutes or longer to download the code, versus less than 30 seconds on a normal serial port. It probably has something to do with how the loader negotiates the transfer speeds; I.E. the USB converter may have an intrinsic delay that throws the timing calculations off.


wow so bad? The only problems i came across with some brand of dongle is that the downloader doesn't detect the controller at all.. probably of incorrect voltage levels. The one i used with the IFI Loader still does the flashing within 30+ seconds.. I'd say to be safe, "try before you buy".

[mtaman02]

Dell actually sells laptops with Serial Ports. The Latitude D510's that we have all have serial ports on them. The problem is, I just visited the Dell website, and they don't sell the D510's anymore. You'll have to check out the specs on some of the other laptops they have to see if they still have the option for Serial Ports.

Edit: It's quite possible they are still available on other dell laptops. The D510s that we bought are literally brand new.


If the model is dis-continued try checking there Dell Outlet Store where they keep all the "Refurbished, Brand New / Sent Back or Cosmetically damaged but Fully Functional Laptops" at. I'm pretty sure you can find that model or many others with the DB9 Port such as the Dell Inspirion 8500 or the D510 mentioned above.

[Greg Marra]

If the model is dis-continued...

The Dell D620 is a current model featuring a serial port. I happen to be typing this on one right now.

[Ken Streeter]

... it's really hard to find a laptop that comes with a serial port. .... As others have mentioned, some current Dell laptops include serial ports. In general, Dell's line of "Latitude" laptops are a little more rugged than the Inspiron line and generally also include serial ports. Of the four current Latitude machines (D420, D520, D620, D820) only the ultra-lite D420 does not include a standard 9-pin serial port. Each of the D520, D620, and D820 include a serial port as standard. I have used D600 and D610 units frequently over the past few years and have been very happy with their reliability and performance. I particularly like their magnesium-alloy cases as they make for a much more durable laptop.

--ken

PS: No, I don't work at all for Dell; just a happy Latitude customer. (I can't make the same claim for an Inspiron 8100 I own -- it's not constructed as solidly and I've had a few problems with it, including a flaky screen and an overheated hard drive.)

[mtaman02]

I must say I have 3 Dell Inspirion Laptops 1150, 5160 and 8500. Out of the 3 laptops I have had a nice portion of problems of course these laptops I bought were refurbished so anything that can go wrong will go wrong. I don't have any regrets though only because the warranty is as good as gold but their tech support is as good as ****. Aside from that I'm a happy customer I also previously owned their MP3 Player and I currently own the Dell A920 Printer/Scanner/Copier and have had no problems with those items.

Getting back to the topic though there are quite a few laptops that come with the DB9 as a standard option much like the 3 1/2" Floppy Drive. If all you are doing with the laptop is programming and "nothing" else (e.g. 3d Studio Max, Web Page Design) Take a ride to the local Second Chance store and see if they have a fairly newish but not completely oldish laptop they are selling that comes with the DB9 Port for a decent price. You will be surprised at what you can find in a Second Hand / Chance Store.

[Astronouth7303]

It's notable that the highest common serial speed (115200) is faster than USB 1.0. Keep in mind that the USB side has to transmit all data, all signal lines, and configuration over its Rx/Tx lines.

I'm willing to bet money that some manufactures have not designed for USB 2 or higher-baud applications.

Rule of thumb: if it doesn't work with the dashboard, don't use it. The dashboard runs at 115200 and is not configurable. Dig around if you need suggestions.

[Dave Flowerday]

It's notable that the highest common serial speed (115200) is faster than USB 1.0.
You may want to recheck your numbers. USB 1.0 (aka "low speed USB") is 1.5Mbps, quite a bit more than 115,200bps used for serial. At any rate, nearly all devices support at least USB 1.1 (aka "full speed USB") which is 12Mbps. USB 2.0 ("high speed") is 480Mbps.

[Astronouth7303]

You may want to recheck your numbers. USB 1.0 (aka "low speed USB") is 1.5Mbps, quite a bit more than 115,200bps used for serial. At any rate, nearly all devices support at least USB 1.1 (aka "full speed USB") which is 12Mbps. USB 2.0 ("high speed") is 480Mbps.

Your right, my bad. :o

USB 1.0 "low speed" comes out to 1500000 bits/second. This would include any encoding, bit shuffling, USB overhead, etc.

Serial comes out to 92160 data bits/s (assuming 8N1 configuration, which is fairly standard; this is found by multiplying the baud rate by 80%=0.8).

Also, USB is half-duplex query-based. USB is succebtable to congestion (that is, a lot of devices on the same hub will slow down bandwidth). Every USB packet is at least 22 bytes long (for the header).

Serial is simple; the Tx and Rx lines just transmit data at the baud. So there is no overhead (handshaking and transmission control is often done with secondary lines).

[AV_guy007]

about serial being faster than USB. i don't have the facts to back this up but a Friend and i were programing vex bots over the summer. i had the standard vex USB to serial adapter plugged into a USB 1.1 port and my Friend was just using a standard serial cable. i noticed that his code loaded at least 5 times faster than mine every time. :ahh:

[Cai ZhongHan]

Seeing as the port replicator interfaces directly to the mainboard of the laptop over a high-speed bus, chances are it would be more like adding a daughterboard with a serial port and it might even be assigned IRQs and I/O addresses by the laptop's BIOS, in which case it should be indistinguishable from a normal serial port.

Just my $0.02. :)

Yes, that's the case with my IBM Thinkpad.
I/O Range:03F8-03FF
IRQ: 04
Location: on Intel(R) 82801DBM LPC Interface Controller - 24CC