From: Barry Watzman on
Well, I found out how it's wired .... a friend of my son built a system
with a P5WD2-E Premium, which has such a com port also, didn't use the
COM port dongle and left it here.

Starting with the stripe edge of the cable (pin 1 for both the DB-9 and
the COM1 motherboard header), the first 5 wires go to the 5 DB-9 pins 1
thru 5 (the 5 pins in the row of 5), the next 4 wires to go pins 6-9
(the 4 pins in the 4-pin row) in that order.

[There is an "alternative" standard which wires every other pin to the
two rows, as if the DB-9 was an IDC socket. Many motherboards and other
devices use the alternative standard, but Asus does not.]

I have a bunch of them, I have a drawer full from the days of the "AT"
motherboard standard (pre-ATX days, mid 1990's).

Me wrote:

> Barry is correct it does not show it. I was thinking my A8V-Deluxe had one
> but upon looking I got a Gamepad bracket for the onboard sound card, not the
> DB-9 neither of which I would use.
> I was going to give it to you but alas I don't have one.
> "Barry Watzman" <WatzmanNOSPAM(a)> wrote in message
> news:44E8B314.10005(a)
>>I have not bought the motherboard yet, but the rear bracket is not listed
>>in the contents in the manual and it is not shown in the photos on Newegg's
>>site which shows all contents (or at least it wasn't shown when I looked
>>There are two different "industry standards" for such parts with different
>>pinouts. I have many of both of them (left over from the pre-ATX days
>>with AT motherboards), but I need to know which one to use. Yes, Asus has
>>them at their "store" for $7, but the shipping costs more than the item
>>and there is a major hassle factor. Frankly, I'd rather make one if it
>>came to that. But in any case, no matter what, the pinout should be in
>>the manual and it isn't.
>>GHalleck wrote:
>>>Barry Watzman wrote:
>>>>The Asus P5B motherboard has a header on the motherboard for a COM1
>>>>serial port, but [stupidly, in my view] no DB-9 connector on the rear
>>>>I/O shield.
>>>>Unfortunately, Asus neither supplies a bracket with the DB-9 socket, nor
>>>>does the manual give a pinout for the header connector.
>>>>[Could Asus have done anything more to further increase the difficulty
>>>>of actually using this port? I don't think so; what we are seeing here
>>>>is industrial strength stupidity at work.]
>>>>Has anyone determined the pinout of the motherboard header for the COM1
>>>>serial port? There were, years ago before the ATX standard came into
>>>>being, two different and incompatible "standards" for such a connector,
>>>>not to mention the possibility that Asus followed neither of them.
>>>Where was the motherboard bought? ASUS certainly does provide
>>>a rear-plane bracket with DB9 connector for use with the serial
>>>header. If unable to resolve with seller, the header pin-outs,
>>>IIRC, follow industry standard and getting a replacement should
>>>not be difficult. If all else fails, there is the ASUS store that
>>>can be linked from the ASUS website.
From: Barry Watzman on
Summarizing this information (which agrees with what I found to be the
case based on investigating the a cable from a P5WD2-E Premium (I think
we can safely assume that all MODERN Asus boards use the same pinout)):

There are two possible wiring patterns for serial port headers.
Asus uses the wiring pattern is called AT-EVEREX-INTEL Version.

This is the other wiring pattern, and maybe this is the one you
bought. It is called DTK Version. Note that this is the one that does
NOT work with Asus motherboards:

RoyB wrote:

> The attached should be helpful re: Serial port on P5B