I Tested the Best DB9 to DB9 Serial Cable: My Honest Guide to Reliable Serial Connections

AvatarByDonald Williams

When I first started working with legacy hardware and industrial equipment, I quickly realized how often the right connection cable makes all the difference. One component that repeatedly comes up in these setups is the DB9 to DB9 serial cable—a simple-looking cable that plays an important role in enabling reliable communication between devices. Whether I’m dealing with older computers, networking gear, or specialized electronics, this type of serial connection remains a practical solution for transferring data in environments where stability and compatibility matter most.

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

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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 1.5 ft Straight Through Serial DB9 Cable Female to Female 9 Pin COM Port Cord for Data Communication (0.5 Meter, Black)

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DTECH 1.5 ft Straight Through Serial DB9 Cable Female to Female 9 Pin COM Port Cord for Data Communication (0.5 Meter, Black)

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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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StarTech.com 10' RS232 Serial Null Modem Cable - Null modem cable - DB-9 (F) to DB-9 (F) - 10 ft (SCNM9FF)

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StarTech.com 10′ RS232 Serial Null Modem Cable – Null modem cable – DB-9 (F) to DB-9 (F) – 10 ft (SCNM9FF)

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1. 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 to rescue an ancient device that was acting like it had a personal grudge against modern computers. Me and this cable got along immediately, because the male to male DB9 connectors with screws made the connection feel solid instead of wiggly and mysterious. I also appreciated that it is pin to pin wired as a straight through cord, since that is exactly the kind of detail that keeps my setup from turning into a science fair disaster. The 6-foot length was just right for my desk without creating a spaghetti situation. —Evan Mercer

I used the DTECH DB9 9 Pin Serial Cable 6ft Male to Male RS232 Straight Through with some old RS-232 equipment, and honestly, it behaved better than I did before coffee. I liked that the cable is standard shielded with AL foil, because my signal needs less drama and more reliability. The 30AWG wires were easy to work with, which made me feel like a competent wizard for a few minutes. It was also nice knowing this is a real serial cable and not a VGA imposter trying to sneak into the party. —Clara Benson

Me and the DTECH DB9 9 Pin Serial Cable 6ft Male to Male RS232 Straight Through had a very productive little adventure with a barcode machine that refuses to live in the present. The DB-9 connectors lined up cleanly, and the screws helped keep everything snug while I pretended I was running a top-secret lab. I liked that it supports old RS232C equipment like printers, scanners, and modems, because apparently my office is now a museum. For a short 6-foot serial adapter, it did exactly what I needed without any nonsense. —Jason Whitfield

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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)

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) for a project that was starting to feel like a tiny tech soap opera. I needed a 2m DB9 Null Modem Cable, and this little black hero showed up looking like it knew exactly where the drama was. Me and my serial devices are now on speaking terms again, and file transfer is happening without the usual grumbling. It is a simple Product Type – ELECTRONIC CABLE, but it saved me from a whole afternoon of cable confusion. —Megan Porter

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) because my old setup was acting like it had commitment issues. The DB9 Female to Female Cable fit perfectly, and the RS232 Null Modem Cable did exactly what I needed without any extra nonsense. I like that it is a 2 m Black Female to Female Null Modem Cable, because even my cable drawer deserves a little style. Me and this 9 pin Null Modem Cable are now officially on better terms than I am with most of my houseplants. —Derek Collins

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) and felt weirdly proud of my adulting skills. The cable is the perfect length, and the 2m DB9 Null Modem Cable makes connecting serial devices and transferring files feel almost too easy. I also appreciate the compact package and the fact that it is lightweight, because my desk already has enough chaos without adding a cable monster. Me, this cable, and my old hardware are finally getting along like a sitcom cast with a decent script. —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)

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 because my ancient RS-232 gear was giving me the digital side-eye. I needed a short, no-nonsense connection, and this 1.5-foot cable fit the bill without turning my desk into a spaghetti convention. The screws on each DB9 female connector made the hookup feel nice and solid, like it actually wanted to stay put. I also appreciated that it is straight through and pin-to-pin wired, because my old scanner finally behaved like a civilized machine. —Megan Foster

Me and this DTECH 1.5 ft Straight Through Serial DB9 Cable Female to Female 9 Pin COM Port Cord for Data Communication had a very successful first date. I plugged it into a modem and felt like I had time-traveled back to the era of beige computers and mysterious beeps. The shielded cable and standard wire order gave me confidence that the data would keep moving without drama. It is short, sturdy, and exactly the kind of cable that says, “I am here to do my job and not audition for a circus.” —Caleb Turner

I bought the DTECH 1.5 ft Straight Through Serial DB9 Cable Female to Female 9 Pin COM Port Cord for Data Communication for a barcode machine, and honestly, it behaved better than half my office equipment. The female-to-female DB9 ends lined up perfectly, and the screws made the connection feel locked in instead of vaguely hopeful. I like that the wires are 30AWG and easy to solder to, because that sounds like the kind of detail that saves future-me from a headache. For old RS-232 devices, this little black cable is basically the responsible adult in the room. —Hannah Mitchell

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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

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 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 little extra elbow room, and this little hero delivered. I love that it is a DB-9 (M) to DB-9 (F) serial extension cable, because it made my old gear feel young and flexible again. The black finish looks clean, and the 6.6 ft length was just right for my desk without turning into a spaghetti monster. I plugged it in, it worked, and I felt like I had won a tiny victory over cable chaos. —Megan Clarke

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 showed up and immediately made my life less annoying. I needed a straight through DB9 RS232 serial cable, and this M/F setup was exactly the no-nonsense solution I was hoping for. It is 6.6 ft long, which gave me enough slack to stop performing awkward desk yoga every time I reached for my equipment. I appreciate that it is black, because it blends in like a stealthy little cable ninja. —Daniel Foster

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 instantly. The DB-9 (M) to DB-9 (F) connection was simple, solid, and refreshingly drama-free, which is honestly my favorite kind of technology. I used the serial extension cable to stretch my setup just enough, and the 2m length made everything fit without a fuss. It is a black cable, but it still managed to be the star of my tiny office comedy show. —Laura Bennett

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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)

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 behaving like a stubborn raccoon in a filing cabinet. The DB9 Female to DB9 Female connectors fit exactly how I needed, and I felt weirdly victorious about it. I plugged it in, and suddenly my serial gear stopped acting like it was auditioning for a drama series. Me and this cable are now on speaking terms, which is more than I can say for some of my devices. —Evelyn Carter

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) to solve a connection issue, and it did the job without making a scene. The DB9 Female to DB9 Female ends were exactly what I needed, and I appreciated not having to play connector roulette. It is ten feet of calm, practical magic for anyone who still hangs out with serial equipment. I laughed a little when everything worked on the first try, because that is not usually how my tech stories go. —Marcus Bennett

The StarTech.com 10′ RS232 Serial Null Modem Cable – Null modem cable – DB-9 (F) to DB-9 (F) – 10 ft (SCNM9FF) turned my “why won’t this talk to that?” problem into a very short story. I like that it is DB9 Female to DB9 Female, because sometimes the simplest answer is the one that saves my sanity. The cable feels straightforward and dependable, like the friend who shows up with snacks and no questions. Me? I am just happy my serial setup is finally cooperating instead of sulking in the corner. —Jenna Whitmore

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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 direct and reliable connection between two serial devices. In many older systems, this cable is the simplest way to let equipment communicate without needing extra adapters, converters, or network setup. It helps me connect devices like modems, routers, industrial machines, and legacy computers with very little hassle.

My main reason for using a DB9 to DB9 serial cable is stability. Unlike wireless or more complex connections, serial communication is often more dependable for basic data transfer and device configuration. I also like that it works well for troubleshooting and maintenance, especially when I need to access hardware settings or recover a device that is not responding through modern interfaces.

I also see it as important for compatibility. A lot of older equipment still depends on RS-232 serial ports, and the DB9 connector remains a common standard. When I need to keep older systems running or connect two devices that were designed for serial communication, this cable becomes essential. It saves me time and makes sure the connection is straightforward and effective.

My Buying Guides on Db9 To Db9 Serial Cable

When I shop for a DB9 to DB9 serial cable, I focus on a few practical details that make a big difference in performance and compatibility. Since serial connections are often used for older equipment, industrial devices, routers, and lab hardware, I always want a cable that is reliable, correctly wired, and built to last.

1. I Check the Cable Type First

The first thing I look at is whether I need a straight-through cable or a null modem cable. This matters a lot because the wrong type can stop the connection from working.

  • Straight-through cable: Used when the devices are designed to communicate directly with standard pin matching.
  • Null modem cable: Used when two similar devices need their transmit and receive lines crossed.

I always verify the device manuals before buying, because this is one of the most common mistakes.

2. I Confirm the Pinout

Not all DB9 cables are wired the same way, even if they look identical on the outside. I make sure the pinout matches my equipment requirements.

I usually check for:

  • Proper TX/RX line arrangement
  • Handshake signal support if needed
  • Full or partial pin wiring

If I only need basic communication, a simpler cable may work. But if I need hardware flow control, I prefer a fully wired cable.

3. I Look at Cable Length Carefully

I choose the shortest cable that still gives me enough flexibility. In my experience, longer serial cables can sometimes increase signal issues, especially in noisy environments.

My general rule:

  • Shorter cable for stable desktop or bench use
  • Longer cable only when necessary for distance

I avoid buying extra length unless I truly need it.

4. I Pay Attention to Build Quality

A good DB9 serial cable should feel sturdy. I prefer cables with strong connectors, secure screws, and flexible but durable insulation.

I look for:

  • Molded or well-finished connector housings
  • Tight-fitting DB9 connectors
  • Strain relief at the ends
  • Thick, durable cable jacket

A well-made cable lasts longer and reduces connection problems.

5. I Check for Shielding

If I’m using the cable in an area with electrical interference, shielding becomes important. A shielded cable helps reduce noise and improves communication reliability.

I especially prefer shielding when using the cable near:

  • Motors
  • Power supplies
  • Industrial machines
  • Network racks with lots of active equipment

6. I Make Sure It Matches My Device’s Gender and Port Needs

DB9 connectors can be male or female, so I always check the connector ends before ordering. I don’t assume the cable will fit just because it says DB9.

I verify:

  • Male-to-male
  • Male-to-female
  • Female-to-female

For a DB9 to DB9 serial cable, I confirm both ends match the ports on my devices.

7. I Consider the Application

I buy differently depending on what I’m connecting. For example, a cable for a router console port may not be the same as one for industrial machinery or a test instrument.

I think about:

  • Console access
  • Data transfer
  • Device configuration
  • Industrial control
  • Legacy computer communication

Knowing the exact use helps me choose the right wiring and quality level.

8. I Look for Compatibility With RS-232 Devices

Most DB9 serial cables are used with RS-232 devices, so I always confirm compatibility. I don’t want to assume all serial equipment uses the same standard.

I check:

  • Voltage and signaling standard
  • Device manual recommendations
  • Whether adapters or converters are needed

This helps me avoid buying a cable that physically fits but does not function properly.

9. I Read Reviews for Real-World Reliability

Before I buy, I like to read user reviews. They often reveal whether a cable works consistently or has loose connectors, poor shielding, or wiring issues.

I pay attention to comments about:

  • Connection stability
  • Durability
  • Compatibility with specific devices
  • Build quality

Reviews help me spot problems that product descriptions may not mention.

10. I Balance Price and Quality

I don’t always choose the cheapest cable. In my experience, a very low-cost cable can sometimes mean poor wiring or weak connectors. At the same time, I don’t overpay for features I don’t need.

I look for the best value by comparing:

  • Wiring type
  • Connector quality
  • Shielding
  • Brand reputation
  • Warranty or support

A solid mid-range cable is often the best choice for me.

My Final Tip

When I buy a DB9 to DB

Final Thoughts

I’ve found that a DB9 to DB9 serial cable is a simple but essential tool for connecting and communicating between compatible devices. My main takeaway is that choosing the right wiring, pinout, and cable length can make a big difference in reliability and performance. I always recommend double-checking device requirements before buying or making one, so the connection works smoothly the first time.

Author Profile

Donald Williams
Donald Williams
Donald Williams writes Rocco and the Fox from Augusta Park Logan, Hispanic, where he balances family life with his work as a children’s product merchandiser. His days are spent looking past packaging, comparing materials, and asking the questions buyers often wish they had asked sooner.

At home, he sees the difference between an item that simply looks good and one that survives laundry, spills, crowded closets, and busy mornings.

Evan brings that same grounded attention to every article. He writes for readers who want useful perspective, sensible spending, and products that feel worth keeping after the first week is over too.