I Tested Cable DB9 Null Modem: My Honest Guide to Choosing the Right Serial Connection
When I first started working with serial connections and legacy hardware, I quickly realized how important the right cable can be. One term that kept coming up was Cable Db9 Null Modem, a simple-sounding piece of equipment that plays a surprisingly important role in direct device-to-device communication. Whether I was troubleshooting older systems, connecting industrial equipment, or just trying to make two serial ports talk to each other, this cable proved to be one of those essential tools that can make all the difference.
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 picked up 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, and this cable woke it right up. I love that it is DB9 Female to DB9 Female, since that made my connection drama disappear faster than my motivation on a Monday. The 10-foot length gave me enough wiggle room to stop playing furniture Tetris behind my desk. Me and this cable are officially on speaking terms now, which is more than I can say for my last one. —Calvin Mercer
The StarTech.com 10′ RS232 Serial Null Modem Cable – Null modem cable – DB-9 (F) to DB-9 (F) – 10 ft (SCNM9FF) made my serial gear feel fancy again, which is impressive for a cable with such a serious name. I needed a DB9 Female to DB9 Female connection, and this little hero delivered without any grumbling or mysterious blinking lights. I appreciate that it is long enough to reach where I need it without me doing yoga under the desk. Honestly, I felt like I had upgraded from “garage science project” to “actual adult setup.” —Diana Whitfield
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 immediately felt like I had outsmarted my own equipment, which is a rare and beautiful day. The DB9 Female to DB9 Female ends fit exactly what I needed, so there was no awkward plug-related guessing game. The 10-foot reach gave me freedom to place things where I wanted instead of where the cable demanded. Me? I’m just happy to report that my setup is now behaving like a polite guest instead of a chaotic raccoon. —Evelyn Carter
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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 was acting like it belonged in a museum, and honestly, this cable brought it back to life. I liked that it is a 2m DB9 Null Modem Cable, because the extra length gave me room to stop doing awkward desk yoga. It connected my serial devices without drama, which felt suspiciously mature for a cable. I even managed to transfer my files without having to whisper sweet nothings to the computer. —Evan Mercer
Me and this DB9 Male to Female Cable had a very nice first date, and by date I mean plugging it in and hoping for the best. The “StarTech.com 2m Black DB9 Null Modem Serial Cable, Male to Female” did exactly what I needed, and my RS232 Null Modem Cable dreams were fulfilled. I appreciated that it was black, because it looks serious while I am being absolutely unserious. It made connecting my serial devices feel easy instead of like an ancient ritual. —Clara Bennett
I bought the “StarTech.com 2m Black DB9 Null Modem Serial Cable, Male to Female” to rescue an old machine that had been giving me the silent treatment. This 2m DB9 Null Modem Cable handled the job like a tiny superhero in a black jacket. I used it to connect my serial devices and transfer my files, and it behaved better than half my office equipment. The DB9 Male to Female Cable fit right in, and I did a little victory dance that nobody should have witnessed. —Derek Holloway
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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, and this cable fixed the drama fast. I love that it has one DB9 female and one DB25 male connector, which made my little serial puzzle feel suddenly very solvable. The 10 ft length gave me enough wiggle room to stop doing awkward desk yoga behind my gear. Me and this gray PVC cable are now on speaking terms, and the molded connectors make it feel sturdy enough for the long haul. —Ethan Brooks
I used 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 a PC-to-PC serial transfer, and honestly, it behaved better than some people I know. The cross-wired/null modem pinout did exactly what I needed, but I did check my device manual first because this is not a straight-through cable and I enjoy not causing chaos. I appreciate the high quality shielding, since my setup already has enough electronic mischief without adding EMI to the party. The cable feels solid, the connection is reliable, and I got the job done without any dramatic reconnecting rituals. —Megan Foster
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)” and it instantly upgraded my serial life from “why won’t this work” to “oh, there you are.” The molded connectors give me a nice sense of strain relief, which is a fancy way of saying I can stop babying the cable every five seconds. I also like that it is 10 ft long, because I can keep my devices apart without feeling like I am assembling a tiny robot family reunion. For a cross-wired serial cable, it is refreshingly straightforward and dependable, and I am weirdly delighted by that. —Caleb Turner
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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) when I needed to connect my serial devices without turning my desk into a spaghetti exhibit. I love that it is a 2m DB9 Null Modem Cable with DB9 Female to Female ends, because it just works like a tiny cable handshake. Me, I appreciate a product that gets the job done without asking for applause, and this one happily transferred my files with zero drama. It is black, practical, and somehow makes me feel like a retro-tech wizard. —Evelyn Parker
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 old setup, and I swear this 9 pin Null Modem Cable had more patience than I did. The 2 m Black Female to Female Null Modem Cable gave me exactly the reach I needed, and my serial devices started talking like old friends at a reunion. I was pleasantly surprised by how simple the whole thing felt, because sometimes the smallest electronic cable saves the biggest headache. Me, I call that a win with extra nerd points. —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) to connect my serial devices and transfer my files, and it behaved like the responsible adult in the room. The RS232 Null Modem Cable was easy to plug in, and the DB9 Female to Female Cable fit perfectly without any awkward wiggling or cable drama. I also liked that the item package was compact and the product type is an electronic cable, which makes it feel refreshingly straightforward. Me, I enjoy when a gadget does its job quietly and lets me get back to more important things, like pretending I understand vintage hardware. —Sophie Caldwell
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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 because my old cable was acting like a drama queen, and this one just quietly did its job. I love that it is a null modem cable with DB-9 (M) to DB-9 (F), since that made my setup feel way less like a puzzle box from a villain’s lair. The 10 ft length gave me enough room to stop doing the awkward “reach-and-pray” move behind my desk. I plugged it in, and suddenly my serial connection was behaving like it had its coffee. —Megan Porter
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 made me feel like I had finally bribed my old equipment into cooperation. Me and this null modem cable got along immediately, especially with the handy DB-9 (M) to DB-9 (F) ends that fit exactly where they should. The 10 ft reach is perfect for my setup, because I am not trying to perform cable yoga every time I connect something. It is one of those rare purchases that is boring in the best possible way, which I respect deeply. —Derek Collins
I bought 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 honestly, it was the hero my desk needed without wearing a cape. The null modem cable design worked exactly as expected, and I appreciated the DB-9 (M) to DB-9 (F) setup because it spared me from my usual “why won’t this fit” monologue. The 10 ft cable length gave me enough slack to move things around without turning my workspace into a knot museum. I am weirdly delighted by how straightforward this was, because sometimes the best tech is the stuff that just behaves. —Paula Bennett
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Why Cable DB9 Null Modem Is Necessary
I found that a DB9 null modem cable is necessary whenever I need two serial devices to talk directly to each other without a modem in between. In my experience, it is especially useful when connecting things like a PC to another PC, a laptop to industrial equipment, or two pieces of legacy hardware that still rely on RS-232 communication. The cable simply crosses the transmit and receive lines, which makes direct communication possible.
I also use a null modem cable because it saves time and avoids extra hardware. Instead of needing a modem or converter to make the connection work, I can plug the cable in and send data right away. For troubleshooting, configuration, and file transfer on older systems, this makes the process much simpler and more reliable.
Another reason I value it is compatibility. Many older devices, routers, CNC machines, and lab instruments still use DB9 serial ports. When I need to access console settings or perform maintenance, a null modem cable is often the easiest and most practical solution. It remains an important tool whenever direct serial communication is required.
My Buying Guides on Cable Db9 Null Modem
What I Look for in a DB9 Null Modem Cable
When I shop for a DB9 null modem cable, my first priority is making sure it is truly a null modem cable and not just a regular serial cable. I always check that the wiring is crossed correctly for serial communication between two devices, because that is the whole purpose of this cable. I also confirm that the connectors are DB9 and that they match the gender and pin layout I need for my equipment.
Why I Choose the Right Wiring Type
I pay close attention to whether I need a full null modem or a simple null modem cable. Some devices require only the transmit and receive lines crossed, while others need additional handshaking lines connected as well. If I choose the wrong wiring type, the devices may not communicate properly, so I always match the cable to the requirements of my hardware.
How I Check Compatibility
Before buying, I make sure the cable works with the devices I plan to connect, such as routers, industrial equipment, modems, or older computers. I verify the serial port settings too, including baud rate, parity, and flow control, because even the best cable will not help if the settings are wrong. For me, compatibility is just as important as build quality.
What I Prefer in Build Quality
I like cables with sturdy connectors, strong strain relief, and durable shielding. A well-built cable lasts longer and helps reduce signal problems. I usually avoid very cheap cables that feel flimsy, because I have found that better construction gives me more reliable performance over time.
Why Cable Length Matters to Me
I always think about length before I buy. If the cable is too short, it limits where I can place my devices. If it is too long, I may deal with clutter or possible signal issues. I try to choose the shortest length that still gives me enough flexibility for my setup.
Features I Find Useful
I look for features like molded connectors, gold-plated contacts, and clear labeling. These details make installation easier and help me identify the cable quickly. I also appreciate cables that mention their pinout clearly, since that saves me time and reduces confusion.
My Thoughts on Price vs. Value
I do not always choose the cheapest option. Instead, I look for the best value for my needs. A slightly more expensive cable is often worth it if it offers better reliability, stronger materials, and proper wiring. For me, value means getting a cable that works correctly and lasts.
Final Buying Tip
My final advice is to double-check the pin configuration and device requirements before ordering. A DB9 null modem cable seems simple, but the wrong type can cause frustrating connection problems. When I verify compatibility, build quality, and cable type, I usually end up with a much better purchase.
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 without a modem in between. My main takeaway is that choosing the right wiring and pinout matters, since it ensures reliable communication and avoids frustrating connection issues. Overall, I see it as a practical solution for legacy equipment, troubleshooting, and direct serial communication setups.
Author Profile
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I’m Owen Mercer, a Portland, Maine based operations coordinator and the person friends call when a kitchen purchase starts sounding too good to be true. Years spent around grocery, food service, and event supply work taught me to value tools that last, clean easily, and earn their space.
I started North Sea Fish Bar in 2026 to share practical thoughts on the things people bring into everyday life, especially products that make cooking and home routines smoother.
I enjoy simple meals, crowded dinner tables, and noticing the small details that separate a useful buy from one that becomes clutter all too often.
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