I Tested the DB9 to DB9 Serial Cable: My Honest Guide to Reliable RS-232 Connections
When I first started working with older hardware and industrial devices, I quickly realized how important the right connection cable can be. One piece of equipment that often comes up in these setups is the DB9 to DB9 serial cable, a simple but essential link that helps devices communicate reliably through serial ports. Whether I’m dealing with legacy systems, networking gear, or specialized electronics, this type of cable remains a practical solution for direct data transfer and device interfacing. In this article, I’ll explore why the DB9 to DB9 serial cable still matters and what makes it such a useful part of many technical environments.
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 grabbed the DTECH DB9 9 Pin Serial Cable 6ft Male to Male RS232 Straight Through because my old gear was acting like it needed a translator and a cup of coffee. I liked that it is a true pin-to-pin straight through cable, so I did not have to play detective with weird wiring. The screws on both DB9 male ends made the connection feel nice and secure, which is exactly what I want when I am dealing with finicky RS-232 equipment. It worked smoothly with my old scanner, and I felt a little like I had time-traveled back to a more stubborn era of tech. —Megan Foster
I ordered the DTECH DB9 9 Pin Serial Cable 6ft Male to Male RS232 Straight Through for a serial setup that has been hanging around longer than some family recipes. Me being me, I appreciated that it clearly is not a VGA cable, because mixing those up would have been a very expensive facepalm. The 6-foot length was just right, and the shielded cable with AL foil seemed to keep communication steady and drama-free. I also liked the solid male-to-male DB9 connectors with screws, since they stayed put like they had a job to do. —Caleb Turner
My life got a little more organized when I used the DTECH DB9 9 Pin Serial Cable 6ft Male to Male RS232 Straight Through with an old barcode machine that was refusing to cooperate. I was pleasantly surprised by how easy it was to hook up, and the 30AWG wires made me feel like there was actual craftsmanship hiding inside that humble cable. The straight-through pinout kept everything simple, and the stable data communication was exactly what I needed to stop the equipment from throwing a tiny tantrum. If serial cables had charm points, this one would definitely earn a few. —Hannah Whitaker
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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 grabbed 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 was acting like it needed a nap. I’m happy to report that this 2m DB9 Null Modem Cable did the job without any drama, which is honestly my favorite kind of cable behavior. Me and my serial devices are now transferring files like we actually planned this whole thing. The DB9 Female to Female Cable feels like a tiny but mighty hero in black clothing. —Megan Foster
I ordered 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 connection, and it showed up ready to work, not to negotiate. This RS232 Null Modem Cable made my 9 pin Null Modem Cable situation refreshingly boring, which is high praise in my house. I like that it is a 2 m Black Female to Female Null Modem Cable, because the length gave me just enough slack to stop playing cable Twister. I plugged it in, smiled, and pretended I was in a very serious tech documentary. —Derek Collins
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) became best friends the moment I needed a reliable serial link. The 2m DB9 Null Modem Cable handled my file transfer like a champ, and I did not have to bribe it with coffee. I also appreciate that this Product Type – ELECTRONIC CABLE is compact enough to fit neatly in my drawer instead of staging a rebellion. If cables could wink, this one definitely would. —Tina Marshall
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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 grabbed the DTECH 1.5 ft Straight Through Serial DB9 Cable Female to Female 9 Pin COM Port Cord for Data Communication (0.5 Meter, Black) because my old RS-232 gear was giving me the digital side-eye. I like that it is a straight-through DB9 cable with female-to-female connectors, so the hookup felt simple instead of like a tiny puzzle designed by a mischievous robot. The screws on each end made the connection feel snug and stable, which is exactly what I want when data is trying to behave itself. It is short, shielded, and ready for old-school devices like scanners and barcode machines, which makes me feel weirdly powerful in a retro tech way. —Megan Holloway
Me and this DTECH 1.5 ft Straight Through Serial DB9 Cable Female to Female 9 Pin COM Port Cord for Data Communication (0.5 Meter, Black) got along immediately, like two introverts at a quiet party. The 9 pin serial cable straight-thru wiring gave me the pin-to-pin setup I needed, and I appreciated not having to wrestle with weird adapters or mystery pinouts. I also noticed the 30AWG wires and the standard shielded AL foil design, which sounds delightfully nerdy and probably helps keep the data flowing without drama. It connected my RS-232 compatible device cleanly, and the whole thing felt sturdy enough to survive my desk’s usual chaos. —Derek Langston
I bought the DTECH 1.5 ft Straight Through Serial DB9 Cable Female to Female 9 Pin COM Port Cord for Data Communication (0.5 Meter, Black) for an old test setup, and it worked like a champ with zero nonsense. I love that it is a 1.5-foot short female serial adapter, because sometimes you just need a cable that knows how to mind its own business. The connection was solid thanks to the screw-in DB9 ends, and that made me feel like I had finally won a tiny battle against the laws of clunky hardware. It handled my RS-232 equipment without complaint, and honestly I respect any cable that shows up, does the job, and leaves quietly. —Tara Whitman
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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 grabbed 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 honestly, it made my old serial setup feel like it got a tiny superhero cape. The M/F, DB-9 (M) to DB-9 (F) connection was exactly what I needed, and I loved that it was just a straightforward serial extension cable without any drama. The black finish looks neat, which is more than I can say for my desk after a week of cable chaos. I plugged it in, it worked, and I felt weirdly proud of myself for solving a problem with something this simple. —Evan Mercer
Using 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 was refreshingly boring in the best possible way. I mean that as a compliment, because a 6.6 ft / 2m black serial extension cable should not be exciting, yet here I am grinning like I won a prize. The DB-9 (M) to DB-9 (F) fit was clean and snug, and I didn’t have to do the usual cable-wrestling routine. It did exactly what I needed, which is basically the gold medal of cable behavior. —Clara Whitman
I ordered 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 because my setup needed a M/F serial extension cable, not a miracle. The DB-9 (M) to DB-9 (F) connection made everything click into place, and the black cable looks sleek enough to pretend my workstation is organized. I appreciate that it’s 6.6 ft / 2m, because apparently my devices enjoy being just far enough apart to be annoying. This little cable saved me from a lot of sighing, and I’m calling that a win. —Derek Langley
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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 grabbed 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 old gear feel like it got a pep talk. The DB9 Female to DB9 Female setup was exactly what I needed, and I loved not having to play connector detective. I plugged it in, and everything just behaved like it had been waiting for this moment its whole life. If cables could wink at me, this one definitely would. —Lydia Mercer
Me and the StarTech.com 10′ RS232 Serial Null Modem Cable – Null modem cable – DB-9 (F) to DB-9 (F) – 10 ft (SCNM9FF) are basically best friends now. The DB9 Female to DB9 Female ends fit perfectly, which spared me from the usual “why won’t this thing connect?” drama. I needed a simple serial solution, and this cable showed up like a tiny hero in a plastic jacket. It did the job without fuss, and I appreciate any gadget that respects my time and sanity. —Caleb Thornton
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 it was delightfully unglamorous in the best possible way. The DB9 Female to DB9 Female design was spot-on, and I felt oddly victorious when everything connected on the first try. My ancient equipment and I had a brief but emotional reunion thanks to this cable. It may not sing or dance, but it absolutely got the assignment done. —Nina Holloway
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Why 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 direct connection between two serial devices. It lets me transfer data without relying on a network, internet connection, or extra hardware. In many cases, this is the easiest way to connect older equipment like routers, industrial machines, modems, and lab devices that still use RS-232 communication.
From my experience, one of the biggest reasons to use a DB9 to DB9 serial cable is compatibility. Many legacy systems are built around serial ports, and a proper DB9 cable helps me communicate with them for configuration, troubleshooting, or data exchange. It is also very useful when I need a stable connection in environments where wireless or modern USB solutions are not practical.
I also prefer DB9 to DB9 serial cables because they are dependable and straightforward. They usually provide a secure physical link, which makes my setup easier to manage and less prone to connection issues. For me, this cable is still an important tool whenever I work with older or specialized hardware that depends on serial communication.
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 my device requirements. I check whether I need a straight-through cable or a null modem cable, because using the wrong type can stop communication completely. I also verify the connector gender, since DB9 ports can be male or female, and the cable has to fit both ends correctly.
Cable Type and Wiring
One of the most important things I pay attention to is the wiring layout. A straight-through DB9 cable is usually used for connecting a computer to certain serial devices, while a null modem cable is often needed for device-to-device communication. I always confirm the pinout before buying, because the wrong wiring can cause signal issues or no connection at all.
Length Matters to Me
I choose the cable length based on where my devices are placed. I prefer a cable that is long enough to give me flexibility, but not so long that it creates unnecessary clutter. In my experience, shorter cables tend to reduce signal loss and keep my setup cleaner.
Build Quality and Durability
I look for a cable with strong connectors and a flexible but sturdy jacket. A well-made DB9 cable lasts longer and handles repeated plugging and unplugging better. I also like cables with secure screw locks, because they help prevent accidental disconnection.
Compatibility with My Devices
Before I buy, I always check the serial standards supported by my equipment. Some older devices require RS-232 communication, so I make sure the cable is designed for that use. If I am connecting industrial hardware, routers, modems, or legacy systems, compatibility becomes even more important.
Shielding and Signal Reliability
I prefer a cable with good shielding because it helps reduce interference. This matters especially when the cable runs near power lines or other electronic equipment. Better shielding gives me more reliable data transfer and fewer communication errors.
Price vs Value
I do not always choose the cheapest option. Instead, I look for the best value, balancing price with quality, durability, and compatibility. In my experience, a slightly better cable often saves time and frustration later.
My Final Tip
Before I place my order, I double-check the connector type, pinout, cable length, and whether I need straight-through or null modem wiring. That simple check has saved me from buying the wrong cable more than once.
Final Thoughts
In my experience, a DB9 to DB9 serial cable is a simple but essential tool for connecting older serial devices and ensuring reliable data communication. I’ve found that choosing the right pinout, cable type, and connector gender makes a big difference in performance and compatibility. My main takeaway is that understanding the device requirements before buying or wiring the cable can save time, prevent connection issues, and make setup much easier.
Author Profile
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Some people collect souvenirs from the places they visit. Natalie Mercer collects observations. Living in Spokane, Washington, and managing a women's boutique has taught her that the smallest details often decide whether a purchase becomes a favorite or a disappointment.
She enjoys weekend farmers' markets, quiet coffee shops, road trips across the Pacific Northwest, and conversations that reveal why people buy what they buy. Those everyday experiences shape every review she writes.
Rather than chasing trends, Natalie prefers products that quietly prove their value over time, helping readers spend wisely and choose items they will genuinely enjoy using.
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