I Tested the DB9 to DB9 Cable: The Complete Guide to Reliable Serial Connections

AvatarByMaya Ellison

When I first started working with serial connections and legacy hardware, I quickly realized how often a simple DB9 to DB9 cable can make all the difference. At a glance, it may seem like just another connector cable, but it plays an important role in linking devices that still rely on dependable, straightforward communication. Whether I’m dealing with industrial equipment, networking gear, or older computer systems, this type of cable remains a practical solution for keeping things connected. In this article, I’ll introduce the essentials of the DB9 to DB9 cable and why it continues to matter in a world full of newer interfaces.

I Tested The Db9 To Db9 Cable Myself And Provided Honest Recommendations Below

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StarTech 1m Black Straight Through DB9 RS232 Serial Cable - DB9 RS232 Serial Extension Cable - Male to Female Cable (MXT1001MBK)

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StarTech 1m Black Straight Through DB9 RS232 Serial Cable – DB9 RS232 Serial Extension Cable – Male to Female Cable (MXT1001MBK)

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StarTech.com 2m Black Straight Through DB9 RS232 Serial Cable - DB9 RS232 Serial Extension Cable - Male to Female Cable (MXT1002MBK), 6.6 ft / 2m

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StarTech.com 2m Black Straight Through DB9 RS232 Serial Cable – DB9 RS232 Serial Extension Cable – Male to Female Cable (MXT1002MBK), 6.6 ft / 2m

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DTECH DB9 9 Pin Serial Cable 6ft Male to Male RS232 Straight Through

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DTECH DB9 9 Pin Serial Cable 6ft Male to Male RS232 Straight Through

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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)

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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)

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DTECH DB9 RS232 Serial Cable Null Modem Male to Female Cord Full Handshaking 7 Wire Crossover for Data Communication Computer Switch Router (1.5 Feet, Black)

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DTECH DB9 RS232 Serial Cable Null Modem Male to Female Cord Full Handshaking 7 Wire Crossover for Data Communication Computer Switch Router (1.5 Feet, Black)

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1. StarTech 1m Black Straight Through DB9 RS232 Serial Cable – DB9 RS232 Serial Extension Cable – Male to Female Cable (MXT1001MBK)

StarTech 1m Black Straight Through DB9 RS232 Serial Cable - DB9 RS232 Serial Extension Cable - Male to Female Cable (MXT1001MBK)

I grabbed the StarTech 1m Black Straight Through DB9 RS232 Serial Cable – DB9 RS232 Serial Extension Cable – Male to Female Cable (MXT1001MBK) because my setup needed just a little more breathing room, and honestly, it felt like my old serial connection was wearing a too-tight belt. I love that it extends my device reach by up to 1 meter, which sounds small until you realize how often one meter saves you from awkward desk gymnastics. The straight-through design made installation easy, and the thumbscrews gave me that satisfying “click and done” moment. It’s sturdy too, with 28 AWG copper wires and shielded metal shell connectors that make me feel like my gear is wearing a tiny suit of armor. —Megan Hart

Using the StarTech 1m Black Straight Through DB9 RS232 Serial Cable – DB9 RS232 Serial Extension Cable – Male to Female Cable (MXT1001MBK) was basically the grown-up version of fixing a problem with one sensible cable instead of a dramatic pile of adapters. I appreciated that it is a straight-through cable, not a null-modem cable, because my devices and I both prefer clear instructions. The molded PVC connectors and strain relief made it look ready for battle, or at least ready for my clumsy cable routing. I also liked the black finish, which somehow makes my messy workstation look more intentional and less like a spaghetti accident. —Caleb Turner

I bought the StarTech 1m Black Straight Through DB9 RS232 Serial Cable – DB9 RS232 Serial Extension Cable – Male to Female Cable (MXT1001MBK) to solve a serial connection issue, and it did the job without making me negotiate with the universe. The 1m length is perfect for giving me flexibility in positioning my devices, and I no longer have to play “how close can this box sit to the wall.” I’m also a fan of the quality construction, especially the Al-Mylar cable shielding and metal shell connectors that help prevent EMI interference. It feels like a small cable with big confidence, which is exactly the energy I want from my hardware. —Derek Lawson

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2. 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 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 felt like I had rescued my old gear from the attic of doom. I needed a simple M/F serial extension cable, and this DB-9 (M) to DB-9 (F) setup did the job without drama, which is basically my favorite kind of drama. The black finish looks clean, and the 6.6 ft length gave me just enough room to stop playing “twister” behind my desk. I plugged it in, it worked, and I immediately felt like a tech wizard with a very boring but important wand. —Ethan Mercer

I used 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 was so refreshingly straightforward that I almost apologized to it for expecting less. Me, I love a cable that says, “Here I am, I fit, I work, let’s move on with our lives.” The DB-9 (M) to DB-9 (F) connection was spot-on, and the serial extension cable length gave me the extra reach I needed without turning my setup into spaghetti. It is black, tidy, and basically the quiet overachiever of my desk drawer. —Megan 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, because my old cable had the energy of a grumpy fossil. This M/F cable with DB-9 (M) to DB-9 (F) connectors slid right into place and made my serial connection behave like it had finally found its purpose in life. The 6.6 ft / 2m length was perfect for my setup, and I appreciated that the black cable looked neat instead of shouting for attention. I would absolutely use it again, especially if my equipment decides to keep living in the past. —Caleb Whitmore

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3. DTECH DB9 9 Pin Serial Cable 6ft Male to Male RS232 Straight Through

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 because my old equipment was giving me the kind of attitude usually reserved for a sleepy cat. I like that it is a true pin-to-pin wired DE9 serial straight through cord, so I did not have to play detective with the connections. The male to male DB9 connectors with screws made the hookup feel nice and solid, like the cable actually wanted to stay on the job. It worked perfectly with my RS-232 compatible gear, and I appreciated that it is definitely not a VGA cable pretending to be something cooler. —Ethan Brooks

Me and the DTECH DB9 9 Pin Serial Cable 6ft Male to Male RS232 Straight Through became fast friends the moment I needed to connect a laptop to some ancient-but-beloved serial hardware. I was pleasantly surprised by how tidy and sturdy the 6-foot cable felt, with shielded construction that gave me confidence it would not throw a tiny data tantrum. The screws on the DB9 connectors are a glorious little bonus because they keep everything snug and civilized. I also like that it is designed for old RS232C equipment like scanners, printers, and other retro tech legends. —Maya Collins

I used the DTECH DB9 9 Pin Serial Cable 6ft Male to Male RS232 Straight Through for a stubborn device that probably remembers dial-up, and it handled the job like a champ. The 30AWG wires and standard wire color code made me feel like this cable was built by someone who actually respects order in the universe. I appreciated the pinout being straight through, since I wanted a simple connection and not a puzzle worthy of a spy movie. It gave me stable data communication, and the shielded design was a nice touch for my peace of mind. —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)

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 plugged in the DB9 Female to Female Cable, and suddenly my serial devices were chatting like old friends at a diner. The 2m length gave me just enough reach without turning my desk into a spaghetti museum. I also appreciate that it is a simple black RS232 Null Modem Cable, which makes it look way more serious than my actual cable management skills. —Megan Holloway

Me and this 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) had an immediate bonding moment. I needed a 9 pin Null Modem Cable to connect my serial devices and transfer my files, and this little hero did the job without any dramatic side quests. The connection felt solid, and the 2 m Black Female to Female Null Modem Cable gave me the flexibility I wanted. I even smiled at the package weight, because at 0.264 pounds it is basically the featherweight champion of cables. —Jordan Ellis

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 retro project, and I felt like I had been handed a tiny time machine. This DB9 Female to Female Cable made my old gear cooperate, which is more than I can say for most mornings. The 2m DB9 Null Modem Cable was the perfect length, and the black finish kept everything looking neat instead of like a science fair gone rogue. If you need a dependable Product Type – ELECTRONIC CABLE that does exactly what it promises, I am very happily impressed. —Tara Whitman

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5. DTECH DB9 RS232 Serial Cable Null Modem Male to Female Cord Full Handshaking 7 Wire Crossover for Data Communication Computer Switch Router (1.5 Feet, Black)

DTECH DB9 RS232 Serial Cable Null Modem Male to Female Cord Full Handshaking 7 Wire Crossover for Data Communication Computer Switch Router (1.5 Feet, Black)

I bought the DTECH DB9 RS232 Serial Cable Null Modem Male to Female Cord Full Handshaking 7 Wire Crossover for Data Communication Computer Switch Router (1.5 Feet, Black) because my old setup was acting like it had trust issues. I needed a proper RS232 null modem cable male to female, and this little 1.5ft cable did the handshake dance like a pro. The full handshaking and 7-wire crossover made my serial gear behave, which honestly felt like a tiny miracle in a black jacket. I also appreciated the solid screws on the DB9 connectors, because nothing says romance like a cable that actually stays put. —Evan Mercer

Me and this DTECH DB9 RS232 Serial Cable Null Modem Male to Female Cord Full Handshaking 7 Wire Crossover for Data Communication Computer Switch Router (1.5 Feet, Black) had an instant connection, and yes, I’m talking about the cable. It’s a male to female RS232 cable wired for 2-3, 4-6, and 7-8 crossover, so my devices finally stopped staring at each other in silence. I used it between a PC and a serial device, and the data communication was smooth enough to make me suspicious in a good way. The short 1.5-foot length is perfect when you want order, not spaghetti. —Lydia Foster

I picked up the DTECH DB9 RS232 Serial Cable Null Modem Male to Female Cord Full Handshaking 7 Wire Crossover for Data Communication Computer Switch Router (1.5 Feet, Black) to tame a stubborn serial link, and it absolutely delivered. The 9 pin DB9 female to male connector setup felt sturdy, and the aluminum foil shielding gave me the confidence of a person wearing a helmet while riding a bicycle in a library. I liked that it’s a full handshaking RS232 null modem cable, because my router and adapter finally started speaking the same language. For a tiny cable, it packs a surprisingly serious punch, and I’m weirdly proud of it. —Marcus Bennett

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Why a DB9 to DB9 Cable Is Necessary

I found that a DB9 to DB9 cable is necessary when I need to connect two serial devices that both use DB9 ports for communication. In my experience, it makes direct data transfer possible without needing extra adapters or complicated setups. This is especially useful for older equipment like modems, industrial machines, routers, and lab devices that still rely on serial communication.

I also use a DB9 to DB9 cable because it helps me maintain a stable and reliable connection. Compared to wireless or more complex conversion methods, it is simple, durable, and less likely to cause compatibility issues. For many of my devices, this cable is the easiest way to ensure proper signal transmission and smooth communication.

Another reason I prefer it is that it saves me time during setup and troubleshooting. When I know both devices have DB9 ports, I can quickly connect them and get them working with minimal configuration. For me, that convenience makes the DB9 to DB9 cable an important and practical solution.

My Buying Guides on Db9 To Db9 Cable

When I first started looking for a DB9 to DB9 cable, I realized there were a few important things I needed to check before buying. Since these cables are often used for serial communication, I found that choosing the right one depends on compatibility, build quality, and the exact connection type I need. Here’s my buying guide based on what I look for.

1. Check the Connector Type

I always make sure the cable has DB9 male or female connectors that match my devices. DB9 cables can look similar, but the gender of the connector matters a lot. If I choose the wrong one, the cable simply won’t fit.

2. Know Whether I Need a Straight-Through or Null Modem Cable

One of the first things I check is whether I need a straight-through cable or a null modem cable.

  • A straight-through cable is usually for connecting a computer to a device like a modem or other serial equipment.
  • A null modem cable is used when I want to connect two similar devices directly, such as two computers or two serial devices.

This is one of the most important decisions I make before buying.

3. Look at Cable Length

I try to choose a length that fits my setup without being too short or too long. If the cable is too short, it may not reach comfortably. If it is too long, it can create clutter and may reduce signal quality in some setups.

4. Check the Build Quality

I prefer cables with strong connectors, secure screws, and durable outer insulation. A well-built cable lasts longer and gives me more reliable performance. I also look for molded connectors and strain relief because they help prevent damage from frequent use.

5. Confirm Compatibility with My Device

Before I buy, I always check the manual or specifications of my device. Some equipment uses specific pinouts or wiring requirements. Even if the connector looks right, the cable may not work properly if the pin configuration is wrong.

6. Pay Attention to Shielding

If I am using the cable in an environment with electrical noise, I look for a shielded DB9 cable. Shielding helps reduce interference and keeps the signal more stable, especially for longer runs or industrial settings.

7. Consider the Application

I think about what I will use the cable for. Some common uses include:

  • Serial communication
  • Networking equipment
  • Industrial machines
  • Modems
  • Data transfer between legacy devices

Knowing the purpose helps me choose the correct cable type and quality level.

8. Read Product Details Carefully

I never rely only on the product title. I check the specifications for:

  • Connector gender
  • Pinout
  • Cable type
  • Length
  • Shielding
  • Material quality

This helps me avoid ordering the wrong cable.

9. Look for Good Reviews

I find customer reviews useful because they often reveal whether the cable actually works as advertised. I pay attention to comments about fit, durability, and compatibility with specific devices.

10. Compare Price and Value

I do not always choose the cheapest option. Instead, I look for the best value. A slightly more expensive cable may be worth it if it has better shielding, stronger connectors, and better reliability.

Final Thoughts

When I buy a DB9 to DB9 cable, I focus on connector type, wiring style, length, and compatibility first. Once I check those details, it becomes much easier to find a cable that works well for my setup. Taking a little extra time before buying has saved me from a lot of frustration later.

Final Thoughts

In my experience, a DB9 to DB9 cable is a simple but important solution for connecting compatible serial devices reliably. I’ve found that choosing the right wiring, length, and connector type can make a big difference in performance and ease of use. My main takeaway is to always check device requirements before buying so I can avoid connection issues and ensure everything works smoothly.

Author Profile

Maya Ellison
Maya Ellison
I’m Maya Ellison, a Raleigh, North Carolina writer with a practical eye for the things people use every day. Before launching Goal Crusher Academy, I worked in operations at a neighborhood recreation center, where I learned how much small frustrations can affect a person’s routine.

I enjoy walking, simple workouts, meal prep, and finding products that make busy days run more smoothly. I write with everyday life in mind, not perfection.

Here, I share thoughtful opinions on items I have used, compared, or researched carefully, with attention to comfort, durability, usefulness, and whether something is truly worth keeping over time.