TRENDnet
TRENDnet USB to Serial 9-Pin Converter Cable, TU-S9
Bottom line: The TRENDnet USB to Serial 9-Pin Converter Cable ($12.99 on Amazon as of 2026-10-20 22:16 UTC): True RS-232 DB9 port for modems, switch console ports, and serial printers; main trade-off: listed driver support stops at Windows 10 and Mac OS 10.11.
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*Price sourced from Amazon.com. Last updated 2026-10-20. Price and availability subject to change.
Pros & Cons
Pros
- ✓ True RS-232 DB9 port for modems, switch console ports, and serial printers
- ✓ 6Mbps data rate over USB 1.1, and works in USB 2.0 and USB 3.0 ports
- ✓ NDAA compliant for U.S. and Canada government procurement
- ✓ Backed by 2 years of TRENDnet Manufacturer Protection
Cons
- ✗ Listed driver support stops at Windows 10 and Mac OS 10.11
- ✗ 540mm (21 in.) captive cable cannot be swapped or extended at the adapter
- ✗ Ships drivers on CD-ROM, which most current machines cannot read
- ✗ Single DB9 port only, so multi-device serial work needs multiple adapters
Manufacturer description
The TRENDnet TU-S9 USB to Serial 9-Pin Converter Cable bridges the gap between a modern laptop and the RS-232 gear that refuses to retire. If your desktop dropped its DB9 header years ago but you still need to reach a modem, a managed network switch, a console port, or a serial printer, this adapter puts a standard RS-232 9-pin connector on the end of a USB Type A plug. It runs at a 6Mbps data rate, supports USB 1.1, and works in USB 2.0 and USB 3.0 ports, so you are not hunting for a specific port on the machine. The integrated cable measures 540mm (21 in.), with a 25-inch total length…
SpecPicks Verdict
SpecPicks scored TRENDnet USB to Serial 9-Pin Converter Cable using a rating × review-volume × price-fit model applied to published specs and reviews across the cables & connectors category. TRENDnet's cables & connectors lineup sits within the broader category mid-tier; price and specs are the deciding factors over brand loyalty here. Judge it on the specification table and the price rather than on sentiment: check the figures that decide your use case, then put it side-by-side with two or three close alternatives in the Compare tool before clicking through.
Common buyer scenarios for cables & connectors of this kind: matching it to an existing build, replacing a failing part, or upgrading from a previous-generation equivalent. Check the spec table below against your current setup — particularly socket / form-factor / power-rating fields — and confirm compatibility on the retailer's listing before purchase. Prices and stock are set by the retailer and may have moved since this page was last updated.
Frequently Asked Questions
Will the TRENDnet TU-S9 work in a USB 3.0 port?
Yes. The TU-S9 supports USB 1.1 and is compatible with both USB 2.0 and USB 3.0 ports, running at a 6Mbps data rate.
Which operating systems does the TU-S9 support?
TRENDnet lists Windows 10, 8.1, 8, and 7, plus Mac OS 10.11, 10.10, 10.9, 10.8, 10.7, and 10.6. For newer OS releases, check the TRENDnet product listing for current driver availability.
How long is the cable?
The integrated USB cable is 540mm (21 in.), and total length is 25 inches once the RS-232 9-pin and USB Type A connectors are included.
Can I use it to reach the console port on a network switch?
Yes. It provides a standard RS-232 9-pin serial connector, which TRENDnet lists for devices such as modems, printers, and network switches.
Is there a warranty, and is it NDAA compliant?
It is backed by 2 years of TRENDnet Manufacturer Protection, and the TU-S9 is NDAA compliant for U.S. and Canada government installs. Check the product listing for current warranty terms.
Key Features
- USB: The USB to serial adapter supports USB 1.1 and it is compatible with USB 2.0 and USB 3.0 ports with a 6Mbps Data Rate
- NDAA COMPLIANT: With our NDAA compliant USB to Serial 9-Pin Converter Cable, you can plan and install networking solutions that Government customers demand today (U.S. and Canada Only)
- MANUFACTURER PROTECTION: We stand by the quality of our products.The TU-S9 USB to Serial 9-Pin Converter Cable is backed and supported with 2 years of TRENDnet Manufacturer Protection.
- RELIABLE TECH SUPPORT: Our team of advisors, support and tech experts are English speaking, and available for all your needs during normal business hours. We take pride in being there for our customers.
- RS-232 SERIAL CONNECTOR: Connect RS-232 serial devices, such as modems or printers, using the widely supported USB standard found in most laptops and desktops today.
- SUPPORTED OPERATING SYSTEMS: The USB to serial converter adapter is compatible with Windows and Mac operating systems. Windows 10, 8.1, 8, 7. Mac OS 10.11, 10.10, 10.9, 10.8, 10.7, 10.6
Full Specifications
| USB | The USB to serial adapter supports USB 1.1 and it is compatible with USB 2.0 and USB 3.0 ports with a 6Mbps Data Rate |
|---|---|
| Brand | TRENDnet |
| Color | White |
| Finish | White |
| EASY SETUP | Simple installation in seconds of the USB to Serial 9-Pin Converter Cable. Insert the your computer |
| Unit Count | 1 Count |
| Connectivity | USB |
| Model Number | TU-S9 |
| Compatibility | Mac |
| Input Voltage | 5 volts_of_direct_current |
| Nominal Power | 2.5 watts |
| Built-In Media | CD-ROM (Driver and User’s Guide), Quick Installation Guide, TU-S9 |
| Connector Type | USB Type A |
| Item Dimensions | 2.56 x 1.38 x 0.39 inches |
| Mfr Part Number | TU-S9 |
| Number of Items | 1 |
| Number of Ports | 3 |
| Power Plug Type | No Plug |
| Compatible Devices | Gateways, Laptop, Modems, PLC controllers, POS systems, Printer |
| Warranty Description | 2 year |
Ready to buy?
TRENDnet USB to Serial 9-Pin Converter Cable, TU-S9 is listed on Amazon. Price, availability, shipping and returns are set by Amazon and its sellers — check the listing for current terms. SpecPicks earns a small commission on qualifying purchases — thank you for supporting independent review work.
*Price sourced from Amazon.com. Last updated 2026-10-20. Price and availability subject to change.
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