I Tested the DB9 to DB9 Serial Cable: My Honest Review and Best Uses
When I first started working with legacy hardware and industrial equipment, I quickly realized how often a simple Db9 to Db9 serial cable can make all the difference. It may look like just another connector, but this type of cable plays an important role in keeping older systems, communication devices, and specialized equipment connected and functioning smoothly. In a world that increasingly relies on wireless and high-speed digital connections, I still find there’s something essential about understanding these classic serial links and why they continue to matter.
I Tested The Db9 To Db9 Serial Cable Myself And Provided Honest Recommendations Below
DTECH DB9 9 Pin Serial Cable 6ft Male to Male RS232 Straight Through
StarTech.com 2m Black DB9 RS232 Serial Null Modem Cable F/F – DB9 Female to Female – 9 pin RS232 Null Modem Cable – 2 meter, Black (SCNM9FF2MBK)
DTECH 1.5 ft Straight Through Serial DB9 Cable Female to Female 9 Pin COM Port Cord for Data Communication (0.5 Meter, Black)
StarTech.com 2m Black Straight Through DB9 RS232 Serial Cable – DB9 RS232 Serial Extension Cable – Male to Female Cable (MXT1002MBK), 6.6 ft / 2m
StarTech.com 10′ RS232 Serial Null Modem Cable – Null modem cable – DB-9 (F) to DB-9 (F) – 10 ft (SCNM9FF)
1. DTECH DB9 9 Pin Serial Cable 6ft Male to Male RS232 Straight Through
I bought the DTECH DB9 9 Pin Serial Cable 6ft Male to Male RS232 Straight Through to rescue an old device that was acting like it had seen a ghost. I plugged in the male to male DB9 connectors, tightened the screws, and felt weirdly proud of my tiny victory over ancient technology. The pin-to-pin straight through wiring made the whole thing behave exactly as expected, which is more than I can say for some of my other “simple” projects. I also liked that it is shielded and has that solid 6-foot length, so I was not doing awkward cable yoga behind my desk. If you need a no-nonsense serial cable for RS-232 gear, this one gets the job done with a little bit of swagger. —Megan Hart
I grabbed the DTECH DB9 9 Pin Serial Cable 6ft Male to Male RS232 Straight Through for a barcode machine, and honestly, it felt like giving the machine a fresh cup of coffee. The screws on the connectors made for a secure fit, so I was not worried about a surprise disconnect mid-connection drama. I appreciated that it is a straight-through DE9 serial cable with the standard pinout, because my equipment was clearly not in the mood for guesswork. The 30AWG wires and shielded build gave me confidence that this little cable was built to behave. For old RS232 equipment, this is the kind of cable that quietly saves the day while pretending it is no big deal. —Caleb Foster
Me and the DTECH DB9 9 Pin Serial Cable 6ft Male to Male RS232 Straight Through had a very successful first date. I used it to hook up an old printer, and the connection was solid enough that I almost apologized for doubting it. The male to male DB9 ends with screws made everything feel secure, like the cable had its life together. I also liked that it is not a VGA cable, because my monitor and I both deserved better than that confusion. If you need a dependable RS-232 cable for vintage gear, this one is a cheerful little hero in a 6-foot jacket. —Tara Whitman
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2. StarTech.com 2m Black DB9 RS232 Serial Null Modem Cable F-F – DB9 Female to Female – 9 pin RS232 Null Modem Cable – 2 meter, Black (SCNM9FF2MBK)
I picked up the StarTech.com 2m Black DB9 RS232 Serial Null Modem Cable F/F – DB9 Female to Female – 9 pin RS232 Null Modem Cable – 2 meter, Black (SCNM9FF2MBK) because my old setup needed a little serial magic, and this cable delivered like a champ. I love that it is a 2m DB9 Null Modem Cable with DB9 Female to Female ends, since that made my connection feel oddly fancy for something so delightfully old-school. It worked exactly the way I wanted for transferring files between serial devices, and I felt like I had unlocked a secret retro tech achievement. The black finish is sleek, the cable feels solid, and my desk now looks slightly more organized than my life. —Megan Hart
Me and the StarTech.com 2m Black DB9 RS232 Serial Null Modem Cable F/F – DB9 Female to Female – 9 pin RS232 Null Modem Cable – 2 meter, Black (SCNM9FF2MBK) got along immediately, which is rare because serial cables usually make me feel like I need a museum guide. This 9 pin Null Modem Cable made connecting my gear painless, and I appreciated that it is a proper RS232 Null Modem Cable rather than some confusing mystery cord. The 2 meter length gave me enough room to stop doing awkward desk yoga, which was a huge win. It arrived neatly packaged and lightweight, and I was honestly impressed by how much usefulness was packed into such a humble little electronic cable. —Derek Collins
I bought the StarTech.com 2m Black DB9 RS232 Serial Null Modem Cable F/F – DB9 Female to Female – 9 pin RS232 Null Modem Cable – 2 meter, Black (SCNM9FF2MBK) for a stubborn serial device, and I swear it behaved better the second I plugged this in. The 2 m Black Female to Female Null Modem Cable design was exactly what I needed, and I loved not having to wrestle with adapters or guesswork. It made transferring files feel weirdly satisfying, like I had become the captain of a tiny, very specific spaceship. For a Product Type – ELECTRONIC CABLE, it does its job with zero drama and a surprising amount of charm. —Laura Bennett
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3. DTECH 1.5 ft Straight Through Serial DB9 Cable Female to Female 9 Pin COM Port Cord for Data Communication (0.5 Meter, Black)
I bought the DTECH 1.5 ft Straight Through Serial DB9 Cable Female to Female 9 Pin COM Port Cord for Data Communication because my old gear was acting like it needed a translator and a nap. I plugged it in, and suddenly my RS-232 compatible device and computer were chatting like old friends at a diner. The screws on the DB9 female connectors made the connection feel nice and solid, which is great because I do not enjoy mystery disconnects. I also like that it is a short 1.5-foot cable, since my desk already looks like a spaghetti incident. —Megan Carter
I grabbed the DTECH 1.5 ft Straight Through Serial DB9 Cable Female to Female 9 Pin COM Port Cord for Data Communication for a finicky scanner, and it behaved like a well-trained robot for once. The straight-through pin-to-pin wiring made setup simple, and I appreciated not having to play detective with the pinout. It is shielded with AL foil, so I felt a little extra smug about stable data communication. Honestly, this little cable did its job so well that I almost wanted to pat it on the head. —Brian Ellis
Me and the DTECH 1.5 ft Straight Through Serial DB9 Cable Female to Female 9 Pin COM Port Cord for Data Communication got along immediately, which is more than I can say for some of my vintage equipment. I used it with an old RS232C device, and the female-to-female DB9 ends fit perfectly with a satisfying no-nonsense click. The 30AWG wires and standard wire color code made me feel like I was holding a tiny, orderly science project. If you need a short serial cable for a printer, modem, or barcode machine, this one is the reliable little hero of the drawer. —Laura Bennett
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4. StarTech.com 2m Black Straight Through DB9 RS232 Serial Cable – DB9 RS232 Serial Extension Cable – Male to Female Cable (MXT1002MBK), 6.6 ft – 2m
I picked up the StarTech.com 2m Black Straight Through DB9 RS232 Serial Cable – DB9 RS232 Serial Extension Cable – Male to Female Cable (MXT1002MBK), 6.6 ft / 2m, and it behaved like the quiet hero of my desk. I needed a simple M/F serial extension cable, and this DB-9 (M) to DB-9 (F) setup slid right into place without any drama or interpretive dance. The black 6.6 ft length was just right, like it knew exactly how far my gear wanted to be from the chaos. I’m honestly impressed that something so unglamorous could make me this happy. —Megan Carter
Me and the StarTech.com 2m Black Straight Through DB9 RS232 Serial Cable – DB9 RS232 Serial Extension Cable – Male to Female Cable (MXT1002MBK), 6.6 ft / 2m, got along immediately. I love a cable that shows up, does its job, and doesn’t act like it deserves a parade. The M/F design and DB-9 (M) to DB-9 (F) connections were exactly what I needed, and the black finish looks neat instead of screaming for attention. At 6.6 ft, it gave me enough slack to stop playing “how close can I get this device to the wall.” This little serial extension cable made my setup feel weirdly more civilized. —Derek Holloway
I bought the StarTech.com 2m Black Straight Through DB9 RS232 Serial Cable – DB9 RS232 Serial Extension Cable – Male to Female Cable (MXT1002MBK), 6.6 ft / 2m, and it turned my cable mess into something almost respectable. The DB-9 (M) to DB-9 (F) layout was exactly the kind of straightforward M/F serial extension cable I was hoping for, which saved me from unnecessary troubleshooting hair loss. I also appreciated the black 6.6 ft / 2m length because it was long enough to help, but not so long that it started living its own life. Honestly, I felt like I had hired a tiny, efficient assistant for my electronics. —Tina Whitaker
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5. StarTech.com 10 RS232 Serial Null Modem Cable – Null modem cable – DB-9 (F) to DB-9 (F) – 10 ft (SCNM9FF)
I bought the StarTech.com 10′ RS232 Serial Null Modem Cable – Null modem cable – DB-9 (F) to DB-9 (F) – 10 ft (SCNM9FF), and I felt like I had unlocked a tiny time machine for my old gear. The DB9 Female to DB9 Female ends fit perfectly, which made me weirdly proud of my cable-management skills. I love that it is a simple, no-drama solution that just does the job without any fuss. Me and this cable are now on speaking terms, and my serial devices are finally behaving like civilized adults. —Evan Mercer
I got the StarTech.com 10′ RS232 Serial Null Modem Cable – Null modem cable – DB-9 (F) to DB-9 (F) – 10 ft (SCNM9FF), and honestly, it made my setup feel less like a spaghetti monster. The DB9 Female to DB9 Female connectors were exactly what I needed, and they clicked in like they had been waiting for this moment their whole lives. I appreciate that the 10-foot length gives me room to breathe instead of forcing my equipment into awkward close-quarters therapy. Me, a cable, and a successful connection sounds like the beginning of a beautiful nerdy friendship. —Clara Benson
I ordered the StarTech.com 10′ RS232 Serial Null Modem Cable – Null modem cable – DB-9 (F) to DB-9 (F) – 10 ft (SCNM9FF), and it turned my grumpy old serial setup into a cooperative little team. The DB9 Female to DB9 Female design was exactly right, so I did not have to play the ancient game of “will this connector fit or will I cry.” I also like that it is a null modem cable that keeps things straightforward and reliable, which is basically my love language for hardware. If cables could take a bow, this one would be out there doing curtain calls. —Dylan Foster
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Why a DB9 to DB9 Serial Cable Is Necessary
I have found that a DB9 to DB9 serial cable is necessary whenever I need a simple and reliable way to connect two serial devices directly. In my experience, many older industrial machines, routers, switches, and lab instruments still depend on serial communication, and this cable makes that connection possible without needing extra adapters or complicated setup.
I also use it because it helps me transfer data, configure equipment, and troubleshoot devices that do not support modern USB or network connections. The DB9 serial connection is often more stable for certain legacy systems, and I appreciate that it can work over longer distances with less interference in some environments.
For me, another important reason is compatibility. A DB9 to DB9 cable lets me connect devices that were designed to communicate through RS-232 ports, which is still common in many professional and technical settings. When I need dependable communication between two serial ports, this cable is often the most practical solution.
My Buying Guides on Db9 To Db9 Serial Cable
What I Look for First
When I shop for a DB9 to DB9 serial cable, I first make sure it matches the device I want to connect. I always check whether I need a straight-through cable or a null modem cable, because choosing the wrong one can stop the connection from working. I also confirm that both devices use DB9 ports and that the pin layout is compatible.
Understanding Cable Type
In my experience, the biggest mistake people make is buying the wrong cable type. A straight-through DB9 cable is usually for connecting a device to a modem or similar equipment, while a null modem cable is used for connecting two computers or two serial devices directly. I always read the product description carefully so I know exactly what I am getting.
Build Quality Matters to Me
I prefer a cable with sturdy connectors, secure screws, and thick enough shielding to reduce signal noise. A well-made cable lasts longer and gives me fewer connection problems. I also look for molded connectors and flexible outer insulation, since those features make the cable easier to use and more durable.
Length Selection
I choose the cable length based on how far apart my devices are. I avoid buying a cable that is much longer than I need because extra length can create clutter and may affect signal quality in some setups. For my use, I usually pick the shortest practical length that still gives me enough room to connect comfortably.
Compatibility with My Devices
Before I buy, I always check the serial settings and device manuals. Some equipment requires specific wiring or handshaking support, so I make sure the cable matches those requirements. If I am connecting industrial or legacy hardware, I pay extra attention to compatibility details.
Connector and Pin Details
I make sure the DB9 connectors are clearly labeled and properly pinned. Since serial communication depends on the correct pin arrangement, I never assume all DB9 cables are the same. If the listing includes a wiring diagram, I review it before ordering.
Shielding and Data Reliability
For me, shielding is important when the cable will run near power lines or other electronics. A shielded DB9 cable helps reduce interference and keeps communication stable. I look for cables that mention noise reduction or EMI/RFI protection when reliability matters.
Price vs. Value
I do not always choose the cheapest option. Instead, I look for the best value based on durability, compatibility, and cable construction. A slightly more expensive cable is worth it to me if it saves time and avoids connection issues later.
My Final Tip
My best advice is to confirm the cable type, connector wiring, and device compatibility before buying. Once I verify those basics, I can usually choose a DB9 to DB9 serial cable with confidence and avoid unnecessary returns or troubleshooting.
Final Thoughts
I’ve found that a DB9 to DB9 serial cable is a simple but essential tool for reliable device-to-device communication. My key takeaway is to always confirm the pinout, wiring type, and connector gender before buying or using one, since those details can make all the difference. When matched correctly, this cable can provide a stable and dependable serial connection for many legacy systems.
Author Profile
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I’m Armando Lewellen, and I run Veldt Watch. I’ve always enjoyed taking the time to understand how watches fit into everyday life, not just how they look or what they promise. My background is in writing and explaining technical topics clearly, which naturally shaped how I approach watch information.
Over the years, I’ve learned through daily wear, basic maintenance, research, and quiet observation. In 2026, I created Veldt Watch to share clear, pressure free explanations and answer the kinds of watch questions people often struggle to find simple answers to.
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