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While going through some (really) old computer parts I came across a very interesting cable: a female RS232 (9-pin serial) to 3.5mm stereo jack.

Any ideas what this cable might have been used for? (it's not a makeshift DIY cable)

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I remember having an old Fritz ISA > ISDN card using a RS232 to RJ45 connection.

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+1 for cleaning out your old computer parts –  Moab Jan 2 '11 at 21:44
    
Also used for Monarch Pathfinder label printers, for uploading files/firmware to the Rom-Dos memory segments –  user82308 May 21 '11 at 12:51

6 Answers 6

up vote 5 down vote accepted

Some devices (such as graphing calculators) use 3.5mm jacks to transmit data. They use similar signals to normal serial ports, but use a different connector.

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close, i eventually found the corresponding device, it's a data logger for a cold storage, logging temperatures from various sensors –  Molly7244 Dec 13 '09 at 16:27
    
That is the type of cable that iogear ships with their KVM (and maybe more) to upgrade the firmware. –  gavaletz Jan 29 '10 at 3:44
    
Currently still new devices which uses these type of cables are sold today: conrad.com/ce/en/product/101367/Voltcraft-CM-100-CO2-Meter –  Ruut May 28 at 12:21

Here's one use I found online: RapidRun DB9 to 3.5mm Adapter

Cable image

Quote:

Eliminate the need to run all new cables for RS-232 control of your Audio/Video system. RapidRun's new RS-232 Adapter gives you the flexibility to use existing 3.5mm stereo audio cables or DB9 cables to run 3 conductor RS-232 control signals between your control unit and your video display. This product can be used with all of the DB9 Break-Away Wall Plates and Flying Leads designed for the RapidRun system. RapidRun RS-232 Adapter Features: Supports transmission of serial control signals including RS-232. Fully molded DB9 and 3.5mm connectors provide excellent strain relief. Ideal for use with computers, projectors, and any control unit/display requiring 3 conductor RS-232 serial control. Note: Not all serial control methods are supported by this adapter. This product is intended only for use with 3-wire RS-232 control cables with common ground (pin 5), transmit data (pin 3), and receive data (pin 2). For the exact pinout of your audio/video equipment please contact the manufacturer.

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that's exactly the cable ... however, i'm still puzzled how it came into my posession, as i certainly don't have any such 'control units' or RapidRun systems :) –  Molly7244 Dec 8 '09 at 1:15

I found a cable like this too, and finally figured it out that it came with my old late 1990s Olympus D-360L digital camera. It was used to transfer pictures to the computer (before card readers became common) and as I recall it would use a lot of battery transferring the pictures.

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since you only really need three lines to do serial communication (and in this case we are not using hardware flow control, which would require two extra lines), a DE-9 to stereo jack is all you need for serial communication with anything with an embedded microprocessor.

The two cases I've used this are a serial programming cable to a TI cable modem, so you could get boot messages and command line access for firmware upgrade purposes; and a OneTouch UltraMini Glucose meter. Here the parent company will sell you an overpriced cable just so you can download your timestamped historic testing data into their "free" software app.

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There are some devices (like say a RAID box I have at work) that use a 3.5mm jack instead of a standard 9 pin port to access their built-in console.

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They are typically used as a pinout for digital cameras.

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quite possible, although i only have 2 digi cams (not much of a photographer myself, and older 4 MP Samsung and a 10 MP Fuji, and that cable is probably older than the Samsung. it's not an accessory that i can find any reference in the manuals for either. –  Molly7244 Dec 8 '09 at 1:20

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