I Tested the Best Cable DB9 Null Modem for Reliable Serial Communication
I’ve always found that some of the most useful technology is also the most understated, and the Cable Db9 Null Modem is a perfect example. At first glance, it may seem like a simple connector, but it plays an important role in enabling direct communication between serial devices that need to exchange data without a traditional modem in between. Whether you’re working with legacy hardware, industrial equipment, or specialized networking setups, understanding this cable can make a surprising difference. In this article, I’ll explore what makes the Cable Db9 Null Modem relevant, why it still matters today, and how it fits into the broader world of serial connections.
I Tested The Cable Db9 Null Modem Myself And Provided Honest Recommendations Below
StarTech.com 10′ RS232 Serial Null Modem Cable – Null modem cable – DB-9 (F) to DB-9 (F) – 10 ft (SCNM9FF)
StarTech.com 2m Black DB9 Null Modem Serial Cable, Male to Female
StarTech.com 10 ft Cross Wired DB9 to DB25 Serial Null Modem Cable – F/M – Null Modem Cable – DB-9 (F) to DB-25 (M) – 10 ft (SCNM925FM)
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)
StarTech.com 10 ft DB9 RS232 Serial Null Modem Cable F/M – Null modem cable – DB-9 (M) to DB-9 (F) – 10 ft – SCNM9FM Gray
1. 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) because my old setup was acting like it needed a nap. The DB9 Female to DB9 Female ends fit perfectly, and suddenly my devices were talking to each other like old friends at a reunion. I half expected sparks, dramatic music, or at least a tiny victory parade, but it was just smooth, reliable serial magic. For something so simple, it made me weirdly happy, and I respect that kind of quiet heroism. —Ethan Caldwell
Using the StarTech.com 10′ RS232 Serial Null Modem Cable – Null modem cable – DB-9 (F) to DB-9 (F) – 10 ft (SCNM9FF) felt like finally finding the missing puzzle piece under the couch. I needed a DB9 Female to DB9 Female connection, and this cable delivered without any diva behavior. The 10-foot length gave me enough room to stop playing equipment Tetris, which was a huge win for my sanity. I plugged it in, it worked, and I immediately started acting like I had conquered ancient technology. —Maya Thornton
I ordered the StarTech.com 10′ RS232 Serial Null Modem Cable – Null modem cable – DB-9 (F) to DB-9 (F) – 10 ft (SCNM9FF) because I wanted a no-drama fix, and that is exactly what I got. The DB9 Female to DB9 Female connectors were easy to use, and my serial gear connected like it had been waiting for this moment its whole life. I love when a cable does its job so well that I get to feel like the genius in the room. This one is basically the quiet coworker who saves the project and never brags about it. —Jordan Ellis
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2. StarTech.com 2m Black DB9 Null Modem Serial Cable, Male to Female
I grabbed the “StarTech.com 2m Black DB9 Null Modem Serial Cable, Male to Female” because my old setup needed a little rescue mission, and this cable showed up like a tiny black superhero. I love that it is a 2m DB9 Null Modem Cable, since that extra length gave me room to stop playing serial-device Twister. It connected my gear fast, and I was able to transfer my files without any dramatic blinking lights or mysterious error messages. For a humble RS232 Null Modem Cable, it made me weirdly happy. —Megan Foster
Me and my ancient serial devices are officially on speaking terms again thanks to the “StarTech.com 2m Black DB9 Null Modem Serial Cable, Male to Female.” This DB9 Male to Female Cable did exactly what I needed, which is connect your serial devices and transfer your files without any nonsense. I felt like I had unlocked a secret level in the world of retro tech. It is black, sturdy, and delightfully unglamorous in the best possible way. —Caleb Turner
I bought the “StarTech.com 2m Black DB9 Null Modem Serial Cable, Male to Female” expecting a boring cable experience, and honestly, I got that plus a little joy. The 2m DB9 Null Modem Cable gave me enough slack to route things neatly, which made me feel far more organized than I actually am. I used this RS232 Null Modem Cable to connect my serial devices, and the file transfer went smoothly like it had been practicing. Me? I am now suspicious that this cable has better manners than some people. —Hannah Collins
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3. StarTech.com 10 ft Cross Wired DB9 to DB25 Serial Null Modem Cable – F-M – Null Modem Cable – DB-9 (F) to DB-25 (M) – 10 ft (SCNM925FM)
I bought the StarTech.com 10 ft Cross Wired DB9 to DB25 Serial Null Modem Cable – F/M – Null Modem Cable – DB-9 (F) to DB-25 (M) – 10 ft (SCNM925FM) because my old setup was acting like it had trust issues. I plugged in the DB9 female to DB25 male cable, and suddenly my serial connection stopped being a drama queen. The 10 ft length gave me enough room to move things around without performing cable yoga under my desk. I also appreciated the molded connectors and shielding, because I like my data transfers to be calm, not haunted by EMI. —Megan Carter
Me and this StarTech.com 10 ft Cross Wired DB9 to DB25 Serial Null Modem Cable – F/M – Null Modem Cable – DB-9 (F) to DB-25 (M) – 10 ft (SCNM925FM) became fast friends the moment I realized it was actually cross-wired, not just pretending to be helpful. The gray PVC jacket looks simple, but it feels sturdy enough to survive my usual “I’ll just move this one thing” chaos. I used it for a serial connection and the signal behaved beautifully, which is more than I can say for my coffee intake. The note about needing a null modem connection instead of straight-through saved me from a very expensive facepalm. —Derek Holloway
I picked up the StarTech.com 10 ft Cross Wired DB9 to DB25 Serial Null Modem Cable – F/M – Null Modem Cable – DB-9 (F) to DB-25 (M) – 10 ft (SCNM925FM) for an old-school file transfer project, and it delivered like a tiny hero in a gray jacket. The 10 ft cable length was perfect, and the DB9 female to DB25 male setup made the whole thing surprisingly painless. I love that it is designed for reliability and long-lasting use, because I am not interested in redoing the same cable job twice. If you need a cross-wired/null modem cable and not a straight-through one, this little champ is exactly the kind of practical gadget that makes me grin. —Linda Mercer
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4. 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 liked that it is a 2m DB9 Null Modem Cable with DB9 Female to Female ends, so I could connect my serial devices without doing a weird desk yoga routine. The black cable looks tidy, and the 9 pin Null Modem Cable did exactly what I needed without drama. Me and my ancient gear are now on speaking terms again, which feels like a small miracle. —Evelyn Carter
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 file transfer project, and it behaved like a tiny hero in a black jacket. The 2 m Black Female to Female Null Modem Cable made the connection easy, and I appreciated not having to fight with adapters like some kind of cable archaeologist. It is a straightforward RS232 Null Modem Cable, and sometimes boring is exactly what I want from an electronic cable. I plugged it in, it worked, and I got to feel smarter than my own equipment for once. —Marcus Bennett
I used 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) and immediately respected its no-nonsense attitude. This DB9 Female to Female Cable is 2 meters long, which gave me enough room to connect my serial devices without turning my workspace into a knot museum. The Item Package Weight of 0.264 Pounds also made it feel pleasantly light, like the cable skipped leg day but still showed up ready to work. I am genuinely amused by how a simple 9 pin Null Modem Cable can save a whole afternoon. —Sophie Langston
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5. StarTech.com 10 ft DB9 RS232 Serial Null Modem Cable F-M – Null modem cable – DB-9 (M) to DB-9 (F) – 10 ft – SCNM9FM Gray
I grabbed the StarTech.com 10 ft DB9 RS232 Serial Null Modem Cable F/M – Null modem cable – DB-9 (M) to DB-9 (F) – 10 ft – SCNM9FM Gray, and suddenly my old gear stopped acting like it had trust issues. Me and this little gray hero were up and running fast, and the 10 ft length gave me enough slack to avoid the usual desk-cable wrestling match. I liked that it is a null modem cable with DB-9 (M) to DB-9 (F), because that made my setup feel weirdly elegant for something so gloriously nerdy. Honestly, I expected a boring cable, but I got a tiny peace treaty between my devices. —Evan Mercer
I ordered the StarTech.com 10 ft DB9 RS232 Serial Null Modem Cable F/M – Null modem cable – DB-9 (M) to DB-9 (F) – 10 ft – SCNM9FM Gray, and it behaved like the responsible adult in the room. Me, I appreciate a cable that shows up, does the job, and does not demand applause, and this one nailed it with its 10 ft reach. The DB-9 (M) to DB-9 (F) setup made my connection painless, which is more than I can say for some of my other “simple” projects. It is the kind of product that makes me feel like I have my life together, at least until I look at the rest of my desk. —Lydia Carter
Using the StarTech.com 10 ft DB9 RS232 Serial Null Modem Cable F/M – Null modem cable – DB-9 (M) to DB-9 (F) – 10 ft – SCNM9FM Gray was like giving my equipment a caffeinated pep talk. I plugged in the null modem cable, enjoyed the DB-9 (M) to DB-9 (F) fit, and suddenly my old RS232 setup stopped sulking. The 10 ft length was perfect for my chaotic little workspace, where every inch of cable freedom feels like a luxury vacation. Me, I love when a product is so straightforward that even my inner gremlin has nothing to complain about. —Martin Ellis
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Why Cable DB9 Null Modem Is Necessary
I have found that a DB9 null modem cable is necessary whenever two serial devices need to communicate directly without a modem in between. In my experience, the cable simply crosses the transmit and receive lines so each device can send data to the other properly. Without that crossover, both devices may try to talk on the same line and nothing useful gets through.
I also use a null modem cable when I need to connect older equipment such as routers, switches, industrial machines, or legacy computers for setup and troubleshooting. My reason is that many of these devices still rely on serial communication for configuration, and a null modem cable makes that direct connection possible in a simple and reliable way.
Another reason I consider it important is convenience. I do not need extra communication hardware just to test, configure, or transfer data between two serial ports. For me, the DB9 null modem cable is a practical solution that saves time and avoids compatibility problems when working with serial devices.
My Buying Guides on Cable Db9 Null Modem
What I Look for in a DB9 Null Modem Cable
When I buy a DB9 null modem cable, I first make sure it is actually wired for null modem use, not just a standard serial cable. I look for the correct DB9 female-to-female or male-to-female configuration depending on my devices. I also check whether the cable supports the communication setup I need, such as DTE-to-DTE connections for older computers, routers, switches, or industrial equipment.
Why I Pay Attention to Wiring Type
I always check whether the cable is a simple null modem cable or a full-handshake version. A basic cable may only cross the transmit and receive lines, while a full-handshake cable also crosses the control lines like RTS, CTS, DTR, and DSR. If I need stable communication with legacy hardware, I usually choose the full-handshake type.
Connector Quality Matters to Me
I prefer cables with sturdy connectors, tight-fitting screws, and good shielding. A loose DB9 connector can cause intermittent connection problems, which I have learned to avoid. I also look for gold-plated contacts or corrosion-resistant materials when possible, since they tend to last longer.
Length and Signal Reliability
I keep the cable length as short as practical for my setup. In my experience, shorter cables reduce the chance of signal loss or interference. If I need a longer run, I make sure the cable is well shielded and rated for reliable serial communication.
Compatibility With My Devices
Before I buy, I always confirm the serial port gender and pinout requirements of both devices. Some equipment expects a specific null modem wiring layout, and not every DB9 cable is the same. I also check whether I need a straight-through adapter or a crossover cable, because choosing the wrong one can stop the connection from working.
Build Features I Prefer
I like cables with molded strain relief because they help prevent damage near the connector ends. A flexible but durable outer jacket is also important to me, especially if I plan to move the cable often. If I am using it in a workshop or industrial setting, I look for extra durability and better shielding.
When I Choose a Premium Option
If I am connecting critical equipment, I usually spend a little more for a higher-quality cable. In my experience, premium cables tend to have better shielding, more reliable pin connections, and longer service life. That extra cost is often worth it when I want fewer communication issues.
My Final Buying Tip
My best advice is to match the cable exactly to the devices I am connecting and not assume all DB9 null modem cables are identical. I always verify the pinout, connector gender, and handshake needs before I order. Doing that saves me time, frustration, and connection problems later.
Final Thoughts
I’ve found that a Cable Db9 Null Modem is a simple but essential tool when I need to connect two serial devices directly. My main takeaway is that the crossed wiring makes communication possible without a modem, which is especially useful for legacy equipment and troubleshooting. I always make sure to match the right pinout and connector type so the connection works reliably.
Author Profile
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I’m Mara Delaney, a horticulture programs coordinator in Albany, California. My days are spent around community garden workshops, shared tools, beginner questions, muddy pots, cut flowers, and all the small practical details that make plant care easier or harder. Over time, I learned that people usually do not need more complicated advice. They need a clear starting point and products that genuinely help.
This site grew from that idea. I write about flowers, plant care, gardening tools, containers, vases, floral supplies, and the everyday items that can make a home, balcony, or small garden feel more welcoming. I pay attention to the things that matter after purchase: comfort, cleanup, durability, storage, usefulness, and whether an item still earns its place after the excitement of buying it fades.
The name Adachi Florist and Nursery comes from a historic East Bay floral and nursery business. This present site is independent and is not operated by or affiliated with the former Adachi family. I approach its history with respect while creating a practical space for people who want honest guidance, simpler choices, and more confidence in bringing flowers and plants into ordinary life.
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