Hi all,

Thanks for this forum. It's been a great help so far. But, I have
this question I must pose: I have an HP Pavilion ze4910us with one 1
15-pin VGA port. I wanted to magically transform this into a COM port
by just attaching a 15-pin to 9-pin adapter, but that hasn't done the
trick. I suspect the capacity to recognize a COM port just doesn't
exist by virtue of the fact that there never was one to begin with.

Have I any hope?

By the way, I know of the USB - RJ 232 connectors; I'm trying this for
a very specific reason.

Many thanks.

In article <12jdg86mcnpakb0@news.supernews.com>,
pvdalen <no@spam.invalid> wrote:
>Hi all,
>
>Thanks for this forum. It's been a great help so far. But, I have
>this question I must pose: I have an HP Pavilion ze4910us with one 1
>15-pin VGA port. I wanted to magically transform this into a COM port
>by just attaching a 15-pin to 9-pin adapter, but that hasn't done the
>trick. I suspect the capacity to recognize a COM port just doesn't
>exist by virtue of the fact that there never was one to begin with.

There is much more to it than merely connecting a plug with the right
number of pins. Honestly, you're lucky you didn't irreparably damage your
computer.

>Have I any hope?

If the laptop has a PC Card slot, you can buy a real hardware serial port
for about $100.

>By the way, I know of the USB - RJ 232 connectors; I'm trying this for
>a very specific reason.

which is....?

NO, NOT POSSIBLE.

The 15-pin port is a video port. The 15 to 9 pin adapter that you have
is to allow connection of a 9-pin CGA color monitor (which is still a
VIDEO monitor) to a 15-pin VGA VIDEO port. It cannot convert a video
port into a com port, and if you try it you may damage possibly both the
video card and the device you are connecting, not to mention that it
won't work.

[The damage comes from the fact that video ports are output only, while
a com device will be trying to put signals INTO some pins. Also, some
of the pins on a COM port have NEGATIVE voltages on them, and voltages
larger than 5 volts (typically +12 and -12 volts) which can destroy the
connections on almost any type of port other than a COM port.]

That you would even ask such a question shows such a complete lack of
understanding of the nature of these ports .... the fact that the
connectors are the same in no way means that ANYTHING else about the
ports is the same.

These are the ONLY ways to add a COM port to a laptop that doesn't have one:

-USB to serial device (which often doesn't work)
-PC Card (or express card) serial port (hard to find/expensive)
-Docking station (not even an option on most laptops)
-Ethernet to serial port (very, very rare but they do exist)

There are ***NO*** other ways to do it.


pvdalen wrote:

> Hi all,
>
> Thanks for this forum. It's been a great help so far. But, I have
> this question I must pose: I have an HP Pavilion ze4910us with one 1
> 15-pin VGA port. I wanted to magically transform this into a COM port
> by just attaching a 15-pin to 9-pin adapter, but that hasn't done the
> trick. I suspect the capacity to recognize a COM port just doesn't
> exist by virtue of the fact that there never was one to begin with.
>
> Have I any hope?
>
> By the way, I know of the USB - RJ 232 connectors; I'm trying this for
> a very specific reason.
>
> Many thanks.
>

pvdalen wrote:
> Hi all,
>
> Thanks for this forum. It's been a great help so far. But, I have
> this question I must pose: I have an HP Pavilion ze4910us with one 1
> 15-pin VGA port. I wanted to magically transform this into a COM port
> by just attaching a 15-pin to 9-pin adapter, but that hasn't done the
> trick. I suspect the capacity to recognize a COM port just doesn't
> exist by virtue of the fact that there never was one to begin with.
>
> Have I any hope?
>
> By the way, I know of the USB - RJ 232 connectors; I'm trying this for
> a very specific reason.
>
> Many thanks.
>
Read the specs before you buy one, thats really the
only way to get what you need.
Friend of mine was lucky to be able to return his
laptop. No parr port ,no rs232, no floppy, no firewire.
Geez... was he angry.

"Barry Watzman" <WatzmanNOSPAM@neo.rr.com> wrote in message
news:4536D10A.9010006@neo.rr.com...
> NO, NOT POSSIBLE.
>
> The 15-pin port is a video port. The 15 to 9 pin adapter that you have is
> to allow connection of a 9-pin CGA color monitor (which is still a VIDEO
> monitor) to a 15-pin VGA VIDEO port. It cannot convert a video port into
> a com port, and if you try it you may damage possibly both the video card
> and the device you are connecting, not to mention that it won't work.
>
> [The damage comes from the fact that video ports are output only, while a
> com device will be trying to put signals INTO some pins. Also, some of
> the pins on a COM port have NEGATIVE voltages on them, and voltages larger
> than 5 volts (typically +12 and -12 volts) which can destroy the
> connections on almost any type of port other than a COM port.]
>
> That you would even ask such a question shows such a complete lack of
> understanding of the nature of these ports .... the fact that the
> connectors are the same in no way means that ANYTHING else about the ports
> is the same.
>
> These are the ONLY ways to add a COM port to a laptop that doesn't have
> one:
>
> -USB to serial device (which often doesn't work)

This seems to be Barry's experience - it is not mine. Everything that I
have tried works (including some DOS applications that run in a DOS window).
This may be down to the software driver rather than the actual adapter
itself. I would like to recommend mine but it is a totally unbranded device
that I got off the Internet, so I can't tell you any more about it. I also
have a fairly old Belkin one (that is quite large owing to the DIL 16450
UART), which works with everything except PsiWin (which works albeit
extremely slowly).

> -PC Card (or express card) serial port (hard to find/expensive)

Hard to find? No. The first catalogue I grabbed off my desk practically
fell open at the right page. Expensive? Well, yes, they are rather
expensive. The cheapest one listed is GBP 90. Anecdotal evidence suggests
that these too are dependant on the software driver as it can't occupy a
real ISA IRQ or I/O address via the PC Card slot (because the PC card also
works via a software driver).

The problem in getting either of these two working seems to lie with
applications that access the UART registers directly and use the IRQ. They
rely entirely on the ability of the softwae driver to emulate those
functions.

> -Docking station (not even an option on most laptops)
> -Ethernet to serial port (very, very rare but they do exist)
>

Your best bet would be to take your laptop and RS-232 device to your local
store and try a USB to RS232 connector. If that doesn't work, then try a PC
card. Buy whatever works.

Barry Watzman wrote:
> NO, NOT POSSIBLE.
snip
>
> These are the ONLY ways to add a COM port to a laptop that doesn't have
> one:
>
> -USB to serial device (which often doesn't work)
> -PC Card (or express card) serial port (hard to find/expensive)
> -Docking station (not even an option on most laptops)
> -Ethernet to serial port (very, very rare but they do exist)
>
> There are ***NO*** other ways to do it.
>

I just ***LOVE*** absolutes....

Of course, you're ***absolute***ly right...

But, there exist laptops that have no serial connector yet DO have
COM ports. You can often tell by looking in the BIOS setup.

For example, an optional internal modem often connects to a COM port.
IF you need RS-232 conformance, you'll need buffers. But depending on
what you're doing and how much you want to risk your laptop...

I'm using an internal modem com port to connect directly to a PIC
processor serial port for prototyping and user interface.

I have a Fujitsu laptop that has two internal buffered serial ports
that aren't brought out. Some wire fixed that for a GPS interface.

I didn't say it was easy...
mike

While we may disagree on all of the exact relative merits of different
ways of connecting a serial device to a laptop without a serial port, we
do agree totally with your last paragraph (below). That is, also,
exactly what I would recommend.

M.I.5¾ wrote:

>
> Your best bet would be to take your laptop and RS-232 device to your local
> store and try a USB to RS232 connector. If that doesn't work, then try a PC
> card. Buy whatever works.
>
>

Barry Watzman wrote:

> There are ***NO*** other ways to do it.

Sure there are.

1. Some Dell machines, and I think some Thinkpads, still have parallel
ports. You can use a parallel to serial converter. You won't get native
signals on the legacy COM port, so it may be no better than a USB
converter, OTOH, you are simply changing the COM address to a parallel
port address, and depending on the application and OS, it may work
better than a USB converter.

2. For Lenovo Thinkpads, you can buy a serial/parallel port drive-bay
adapter. This delivers the native signals from the SuperIO or
Southbridge to the ports, with legacy I/O addresses, something you don't
get with the USB adapters (which is why the USB to Serial adapter often
doesn't work).

3. There are IrDA to RS-232 adapters, though this is a pain because the
receiver that receives the IR stream from the computer, and converts it
to RS-232 signals, requires a power supply. Normally these devices are
designed the other way around, converting the serial port of a computer
to IR, but you can go the other way if you really want to, buy using a
null modem and powering the RS-232 tranceiver externally.

mike wrote:

> For example, an optional internal modem often connects to a COM port.
> IF you need RS-232 conformance, you'll need buffers. But depending on
> what you're doing and how much you want to risk your laptop...

Some Lenovo Thinkpads can take a drive bay module with serial and
parallel ports that connect to the signals from the SuperIO. This works
as well as using a PC Card adapter, though it's no cheaper.

"Barry Watzman" <WatzmanNOSPAM@neo.rr.com> wrote in message
news:45378620.5080804@neo.rr.com...
> While we may disagree on all of the exact relative merits of different
> ways of connecting a serial device to a laptop without a serial port, we
> do agree totally with your last paragraph (below). That is, also, exactly
> what I would recommend.
>
> M.I.5¾ wrote:
>
>>
>> Your best bet would be to take your laptop and RS-232 device to your
>> local store and try a USB to RS232 connector. If that doesn't work, then
>> try a PC card. Buy whatever works.

Are you royalty or are there two of you?