What is a DB 9 to 3.5mm quad plug cable used for?

Question

While cleaning up the office today we ran across two odd looking cables still in bags. On one end is a female DB 9 connector and the other end is a 3.5mm plug with 4 contact points. The types of equipment we have are: Dell workstations and servers, HP SANs, Equallogic SANs, Cisco network gear, and symmetricom time servers.

The only thing I found on the net is a speakercraft adapter cable but we've never had anything to do with speakercraft.

UPDATE: We don't have any cameras or video/audio equipment in the area. It can't possibly be for a camera, cell phone, or some other home consumer item since we just can't have that stuff in the area.

No cameras or cell phones allowed in here. I'll take the cable home and upload a picture in about an hour. — murisonc, Mar 25 '13 at 20:35
Throw them all away - within 15 minutes of the garbage truck driving away, a critical piece of equipment will explode. Then you'll know! — Dan, Mar 25 '13 at 23:09
You have a bladecenter switch (or something with severely limited front-panel real estate) that takes that? I've seen weird pinout DB9 to USB form-factor(not real USB) cables before. — cpt_fink, Mar 26 '13 at 04:49

score 6 · Accepted Answer · answered Mar 27 '13 at 18:47

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I finally found them. The cable is a firmware upload cable that came with our IOGEAR GCS1644 KVMs.

answered Mar 27 '13 at 18:47

murisonc

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score 3 · Answer 2 · answered Mar 25 '13 at 22:30

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We've had them lying around too. They're usually thrown in the box to give you serial console access to a wide variety of gadgets. Have a look for ISDN terminals, video projectors or UPS devices. Could even be a graphing calculator!

answered Mar 25 '13 at 22:30

Colin Pickard

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+1 for calculator - fairly sure a TI83 I had years ago had a cable like that – Mark Henderson Mar 25 '13 at 23:49

score 3 · Answer 3 · answered Mar 26 '13 at 08:51

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From the depths of my grey mind I think there's a possibility that it's something used on a VERY old HP MSA SAN array (maybe an MSA 1000?). Happy to be wrong but I'm sure I've seen one years ago like that.

answered Mar 26 '13 at 08:51

Chopper3

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I definitely have a disc pack that uses this for console access, but it's in a colo on the other side of the country at the moment, so I can't go check what it is. – MadHatter Mar 26 '13 at 08:54

score 2 · Answer 4 · answered Mar 25 '13 at 20:38

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In some cases, it is a specially made Video Cable for Polaroid®'s PDC-300, Fun! 320, & Fun! Flash 640 cameras.

answered Mar 25 '13 at 20:38

Eirik Toft

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It might be for a digital camera but not necessarily a Polaroid. As I recall this was commonplace in the pre-USB days. – Gerald Combs Mar 25 '13 at 21:05
Those are all 3 conductor plugs aren't they? – murisonc Mar 25 '13 at 22:09

score 1 · Answer 5 · answered Jul 21 '14 at 03:53

I have one. I mean identical in appearance -- even the mounding of the connectors appears exactly identical.

What I know is we have UPS devices, old APC Back-UPS, etc., but all of them seem to have DB-9. Then we have various generations of KVM switches, but not the manufacturer mentioned having such a port that is unexplained by audio connection. (This would not be audio--nobody in his right mind would hook audio to db-9.) We have iPod, iPad, and iPhone -- but never recall purchasing a cable like that. However I see on eBay such a cable of nearly identical, but metal connector, sold as a "data cable" for iPhone/iPod/iPad. Can't find any documentation to support, and the sale gives none whatsoever.

Another possibility--I have a very old digitizing tablet, separated in location now. (Will relocate in next few months, then can check if fits.)

I present all this for possible elimination. My memory was an older UPS, but can't find one that matches.

score 0 · Answer 6 · answered Mar 25 '13 at 20:39

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many mobile devices use 3.5mm jack for serial console. my bet is that if you open the DB9 housing - you will find a TTL-to-RS232 convertor chip in there

answered Mar 25 '13 at 20:39

Alex P.

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score 0 · Answer 7 · answered Mar 25 '13 at 20:50

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(from a buddy here at work, but sounds right, hope it helps)

There are lots of different applications for a DB9 to 3.5mm plug.

RS232 serial control is my bet here in an IT shop. A 4 port/conductor 3.5 will typically be audio (stereo) plus video (or maybe bi-directional audio, think output and input). For instance, an iPhone uses a TRRS (4 conductor) for the headset. Look for equipment like touch screens, custom hardware, camcorders, etc. that would require a db9 to 3.5mm.

answered Mar 25 '13 at 20:50

TheCleaner

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We've looked at everything we have. No cameras or personal electronics are allowed in the area. – murisonc Mar 25 '13 at 22:11
Another thing that came to mind...what about a music-on-hold device for an older PBX? – TheCleaner Mar 26 '13 at 14:28

What is a DB 9 to 3.5mm quad plug cable used for?

7 Answers7