15 pin COM Header on motherboard

2

On a Lenovo M81 motherboard there is a 15 pin header labelled "COM2".

15 pin header

I know that some serial interfaces can have 15 pins, but thought the most modern variation is 9 pin. I would have expected a 9 pin header on a fairly modern Core i5 PC. I can't find any 15 pin adapters that would convert this into a D-SUB 15 pin serial port.

What perplexes me further is that another, much older Lenovo 9702-7LG has a 9 pin header in the same place. This is also labelled COM2.

9 pin header

Why 15 pins?

And if I were to buy something like this: https://www.amazon.com/StarTech-com-16-Inch-Serial-Bracket-Header/dp/B007UQZD9K how would I connect this to the 15 pin header? Would I simply plug it into the right-most pins?

Andy Foster

Posted 2016-11-10T23:45:10.693

Reputation: 311

The Lenov0 manual indicates that a special cable assembly (which includes an active level shifter chip) is required. If you have a voltmeter (e.g. DMM), then you can confirm this. BTW even if there was a 9-pin header, there are two common pinouts in use on motherboards. IOW there is no single standard for mobo pinout for COM ports.

– sawdust – 2016-11-11T01:12:44.983

See the second part of this answer for the two conventions for 9-pin mobo headers.

– sawdust – 2016-11-11T01:34:13.080

Thank you! Lenovo part number 71Y6217. I've also just realised that the older header is actually 11 pins, not 9, so that's some arbitrary Lenovo thing too. – Andy Foster – 2016-11-11T09:04:12.487

Answers

1

If I remember correctly the 15pin port is "game port", not true serial port. Thus you can't convert it the way you are thinking.

Sometime I have seen them called "COM2" but that is a mistake on the board manufcaturer's side.

The correct cable and external port is this:

enter image description here

TomEus

Posted 2016-11-10T23:45:10.693

Reputation: 3 355

This wouldn't work in this situation. Lenovo are using their own bespoke header so you must purchase the part from them. Not cheap either! A new one is over £100 on some sites. – Andy Foster – 2016-11-11T15:58:50.673

OK, good to know, thanks for the update. All my PCs are using generic MBs like Asus so this was a blind shot.... – TomEus – 2016-11-11T23:20:34.227

Asked: 2016-11-10T23:45:10.693

Viewed: 2 825 times

Active: 2019-08-17T15:02:45.453