DTECH DB9 Female to RJ45 Female Adapter
4.5Editor score
Passive DB9 female adapter
Supports 65-foot extensions
Secure thumbscrew connection
In this guide
An RS232 to RJ45 converter bridges the gap between traditional serial equipment and the familiar eight-position network cables found in offices, workshops, and industrial installations. The right adapter depends on whether you need a simple passive extension, active signal conversion, or genuine Ethernet communication.
This guide compares ten converters based on connector configuration, supported data functions, usable distance, power requirements, surge protection, and suitability for common serial devices. It covers simple DB9-to-RJ45 couplers as well as powered RS232-to-RS485, RS422, and Ethernet gateways for more demanding installations.
Each selection highlights a different practical advantage, from compact passive extension to bidirectional conversion and remote monitoring. Product ratings, connector types, and stated capabilities are included to simplify comparison, while current prices and availability should be checked with the retailer before purchase.
Top 3 Picks for Best RS232 to RJ45 Converter
DTECH RS232 Male and Female Adapter Set
4.7Editor score
Includes matched male adapter
Bi-directional serial extension
Works with Cat5 and Cat6
USR-TCP232-302 Serial Ethernet Server
4.0Editor score
Bidirectional Ethernet conversion
Multiple operating modes
Supports DHCP and DNS
Top 10 Best RS232 to RJ45 Converter in 2026 Compared
The comparison covers passive couplers, active serial converters, Ethernet gateways, and a device-specific USB serial cable, with particular attention to connector gender, signal type, supported distance, and practical hardware features.
ProductsSpecificationsEditor scorePrice
Best Budget
DTECH DB9 Female to RJ45
DB9 female to RJ45
Passive serial adapter
Up to 65-foot extension
No external power
4.5Editor score
Editor's Choice
DTECH Male and Female Set
Mixed-gender adapter pair
Bi-directional serial data
Up to 65-foot extension
No external power
4.7Editor score
Best Premium
DB9 Male to RJ45 Pair
Two-cable adapter package
Male and female options
No external power
UTP cable support
4.6Editor score
DTECH DB9 Male Adapter
DB9 male to RJ45
Passive serial adapter
Up to 65-foot extension
Straight-through pinout
4.2Editor score
Ten Female RJ45 Adapters
Ten-piece adapter set
DB9 female to RJ45
Up to 100-foot extension
Documented signal pinouts
4.8Editor score
USR-TCP232-302 Ethernet Server
Active Ethernet converter
10/100Mbps RJ45 port
Up to 230.4Kbps
DHCP and DNS support
4.0Editor score
DTECH RS232 Active Converter
RS232 to RS485
RS422 four-wire support
Surge and ESD protection
Includes power supply
4.7Editor score
LINOVISION Dual-Port Gateway
RS232 and RS485 inputs
Modbus RTU/TCP conversion
Up to 16 polling hosts
Wall and rail mountable
4.1Editor score
FT231XS USB Serial Cable
USB to RJ45 serial
Six-foot cable length
FT231XS bridge chipset
Requires FTDI driver
4.6Editor score
DB9 Male and Female Pair
Matched male-female pair
Bi-directional RS232 data
Up to 65-foot extension
Shielded nickel-plated contacts
5.0Editor score
1. DTECH DB9 Female to RJ45 – Simple Passive Extension
DTECH DB9 Female to RJ45
DB9 female to RJ45
65-foot maximum distance
Thumbscrew-secured connection
No external power
This DTECH adapter is a straightforward female DB9-to-female RJ45 coupler for extending RS232 serial signals across Cat5 or Cat6 cable. Its 4.5 rating reflects a generally practical design, with the strongest qualities coming from its simple construction, one-to-one pin mapping, and lack of external power requirements. It is intended for serial data rather than VGA video or network conversion.
Pros
- Simple passive construction
- No power supply required
- Works with standard DB9 devices
- Thumbscrews improve security
- Supports Cat5 and Cat6
Cons
- Usually requires a matching adapter
- Does not create Ethernet connectivity
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The adapter maps the first eight DB9 contacts directly to the corresponding RJ45 contacts, with the ninth DB9 contact unused. Thumb screws on the DB9 shell help secure the connection to a compatible device, which is useful in retail, workshop, and industrial environments where loose plugs could interrupt communication. A second, compatible coupler at the remote end can extend the serial path by as much as 65 feet.
Its main limitation is that it does not translate RS232 into Ethernet data. The RJ45 connector only provides a convenient path for the serial signals through twisted-pair wiring. Users must therefore arrange the correct adapter combination at both ends, and the cable itself must preserve the intended pin assignments. Despite that limitation, the passive approach is effective when the objective is simply to replace a bulky DB9 extension cable.
This is a strong choice for users extending a printer, scanner, POS terminal, router, modem, or another standard nine-pin serial device. It is particularly suitable for a straightforward point-to-point installation where no network addressing, protocol conversion, or electrical isolation is needed. For most basic RS232 extension tasks, it offers an uncomplicated solution with fewer components than an active gateway.
A Practical Way to Extend Serial Connections
The main benefit is cable flexibility. Rather than searching for another lengthy DB9 cable, the adapter can use existing Cat5 or Cat6 runs. Its stated 65-foot limit makes it useful for moving a serial endpoint across a room, workbench, or nearby equipment rack.
Secure and Passive by Design
Because it needs no external power, installation is limited to connecting the adapter, cable, and remote coupler. The thumbscrews provide a more secure mechanical fit than an unsecured DB9 shell, which is advantageous in high-use or vibration-prone settings.
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2. DTECH Male and Female Set – Complete Extension Kit
DTECH Male and Female Set
Male and female adapters
Bi-directional serial extension
65-foot maximum distance
Thumbscrew-secured connectors
This two-piece DTECH set includes one DB9 male-to-RJ45 female adapter and one DB9 female-to-RJ45 female adapter. That combination solves the common problem of deciding which coupler belongs at each end of an extension. The 4.7 rating and plug-and-play approach make it one of the most attractive choices for a standard point-to-point RS232 extension.
Pros
- Includes two required adapters
- Supports bidirectional serial data
- No external power required
- Broad device compatibility
- Works with Cat5 and Cat6
Cons
- Serial data only
- Not an Ethernet interface
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The set carries serial signals bidirectionally over Cat5 or Cat6 cable for distances up to 65 feet. Thumb screws help hold the DB9 connections firmly in place, and the adapters are compatible with a broad selection of nine-pin serial equipment, including computers, terminals, CNC machines, PDAs, POS terminals, barcode scanners, printers, modems, scales, and routers. The inclusion of both genders also reduces the likelihood of buying an incompatible combination.
The important distinction is that this is a serial extension kit, not an Ethernet converter. It does not assign an IP address, route traffic through a network, or let a modern Ethernet port communicate directly with an RS232 device without additional software or equipment. Users should also avoid confusing the DB9 connector with a 15-pin VGA connection. The product is designed specifically for standard nine-pin D-sub serial devices.
It is best suited to installers, technicians, and office users who want to bridge two serial endpoints using an existing network cable. The matched set is more convenient than purchasing separate adapters and reduces uncertainty about orientation. For applications that require real network conversion, surge protection, or RS485 and RS422 support, one of the active gateway options in this guide will be more appropriate.
Everything Needed for Two-End Installation
The male and female components are designed to sit at opposite ends of the twisted-pair run. This is a significant convenience over single adapters and helps create a consistent, understandable extension layout.
Bi-Directional Communication Without Complexity
Because the path supports both transmission and reception, the setup can carry a complete RS232 serial conversation rather than only a one-way data flow. The passive design needs no configuration or power connection.
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3. DB9 Male to RJ45 Pair – Flexible Cable Extension
DB9 Male to RJ45 Pair
Male and female adapters
Two-cable package
No external power
UTP Cat5 or Cat6
This DB9-to-RJ45 extender package provides male and female adapter arrangements for carrying RS232 data over twisted-pair cable. Its 4.6 rating indicates strong general appeal, particularly for technicians who need several connection options or who want a product that can be used singly as well as in matched pairs. The adapters require no external power and support common desktop and industrial serial devices.
Pros
- Offers male and female options
- Supports bidirectional transparent transmission
- Uses standard UTP wiring
- No external power needed
- Can function alone or in pairs
Cons
- Distance specifications vary
- Not a conventional Ethernet converter
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The product is described as supporting bidirectional transparent transmission over UTP Cat5 or Cat6. Compatible equipment includes desktop computers, digital machine tools, PDAs, barcode devices, and other standard nine-pin serial peripherals. The male-to-RJ45 configuration makes it useful when the host computer has a male DB9 output and the target device uses a female port, while the female-to-female arrangement covers the inverse configuration.
Published distance details are not perfectly consistent: the description mentions a maximum of 66 feet, recommends use from roughly 1 to 15 meters, and also states that UTP can bridge longer runs. That variation makes it important to treat the cable, interference conditions, baud rate, and local testing as the deciding factors. The product should not be confused with an IP-to-serial gateway merely because the description mentions network interfaces.
This extender is a practical choice for workshops, laboratories, point-of-sale installations, and legacy equipment where DB9 leads are inconvenient. It can be especially useful for users who need more than one connector-gender arrangement. Confirm the pin mapping of both devices and perform a basic loopback or communication test before deploying the adapters across a permanent cable route.
Multiple Connector Arrangements Included
The package covers female-to-female, male-to-female, and male-to-male use cases, depending on the supplied configuration and the devices being connected. This makes it easier to assemble an extension without a separate return trip for a different DB9 arrangement.
Transparent Serial Transmission
The adapter carries serial data across the twisted-pair path without adding a separately powered translation layer. The connection remains most reliable when the cable run, grounding, and baud rate suit the distance and equipment.
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4. DTECH DB9 Male Adapter – Compact Straight-Through Coupler
DTECH DB9 Male Adapter
DB9 male to RJ45
65-foot maximum distance
Straight-through pin mapping
No external power
This DTECH unit converts a DB9 male connection into an RJ45 female connection through a straight-through passive pin map. Its 4.2 rating places it among the more highly reviewed options, while its simple installation makes it appropriate for routine serial extensions. It is built for nine-pin RS232 equipment and should not be mistaken for a VGA connector.
Pros
- Compact passive design
- No power supply needed
- Secured with thumbscrews
- Works with common serial devices
- Supports Cat5 and Cat6
Cons
- Requires compatible remote adapter
- Provides no network functionality
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A useful characteristic is the direct mapping of contacts one through eight, with the ninth DB9 contact left unused. The adapter can form part of a pair that carries serial signals over inexpensive Cat5 or Cat6 cable for up to 65 feet. Thumbscrews help keep the male DB9 connection secure, and the absence of external power reduces installation complexity.
As a passive adapter, it offers no electrical isolation, surge protection, automatic baud-rate detection, or protocol translation. The RJ45 connector is being used as a convenient serial pathway, not as a true network interface. A matching adapter at the opposite end is generally required, and correct pin continuity must be present throughout the installed cable.
Buyers with a male DB9 host port will find this adapter particularly convenient for reaching a remote serial peripheral. It can serve printers, barcode scanners, modems, POS systems, routers, and industrial machine tools where a conventional DB9 extension is inconvenient. Choose it for uncomplicated serial extension; choose an active gateway instead when the device must appear on an IP network.
Straight-Through Wiring Keeps Setup Simple
The one-to-one pin assignment removes the need for configuration after installation. Provided the opposite adapter and cable use the same wiring arrangement, serial data can pass across the network cable in both directions.
Ideal for a DB9 Male Host
This adapter fills a very specific connector gap. It is particularly useful where the computer or controller has a male serial port and the equipment to be reached is too far away for a conventional RS232 extension cable.
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5. Ten Female RJ45 Adapters – Multi-Pack for Installations
Ten Female RJ45 Adapters
Ten-piece female adapter set
Up to 100-foot extension
Documented RJ45 color pinout
Alloy connector construction
This ten-piece set consists of female DB9-to-female RJ45 adapters for carrying RS232 signals over Cat5, Cat5E, and Cat5 network cable. Its 4.8 rating is the highest among the products reviewed, making it appealing for technicians who need several matching couplers or prefer to keep spare units close at hand. The stated reach extends to 100 feet.
Pros
- Highest rating in the list
- Ten adapters included
- Supports 100-foot cable runs
- Clear signal pin documentation
- Durable alloy contacts
Cons
- Female-to-female configuration only
- Does not create Ethernet connectivity
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One practical strength is its clearly documented wiring. The RJ45 color assignments and nine DB9 signal definitions are listed, including carrier detect, received data, transmitted data, data terminal ready, ground, data set ready, request to send, clear to send, and ring indicator. This documentation makes it easier to compare the adapter with the wiring of a specific installation rather than relying on guesswork.
The adapters use alloy transmission contacts to reduce impedance and interference, while the molded ABS body is designed for wear resistance. They remain passive components, however, and their advertised 100-foot capability is a stated maximum rather than a guarantee for every baud rate, cable quality, grounding arrangement, and electromagnetic environment.
The ten-unit format is useful for facility managers, repair technicians, and installers who service multiple serial endpoints. It can also serve as a stock of spares in a maintenance kit. Because the supplied connectors are female on both ends, users should verify that their equipment arrangement can be completed with a suitable male-side counterpart. This set is a passive serial extender, not a network protocol converter.
Useful Stock for Maintenance Teams
Ten identical adapters reduce the need to source individual replacements during equipment servicing. Keeping a few on hand is helpful when legacy serial endpoints are spread across a workshop, warehouse, or retail installation.
Wiring Details Support Better Installation
Documented pin assignments allow an installer to check wire continuity against the equipment manual. This is especially valuable in longer cable runs where a poor connection or incorrect mapping is difficult to diagnose.
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6. USR-TCP232-302 – Full Network Gateway
USR-TCP232-302 Ethernet Server
Bidirectional Ethernet conversion
10/100Mbps RJ45 interface
600bps to 230.4Kbps
Multiple network operating modes
The USR-TCP232-302 is a dedicated serial-to-Ethernet server rather than a passive adapter. Its 4.0 rating reflects a capable device with a steeper learning curve than a simple DB9 coupler. It performs bidirectional transparent transmission between RS232 and Ethernet, allowing legacy serial equipment to communicate across a LAN or, where appropriate, an external network.
Pros
- Adds real TCP/IP connectivity
- Supports DHCP and DNS
- Offers multiple operating modes
- Includes virtual serial software
- Compact industrial module
Cons
- Requires network configuration
- More complex than passive coupler
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The compact module includes a 10/100Mbps auto-MDI/MDIX RJ45 port and supports serial rates from 600 bps to 230.4Kbps. It offers TCP Server, TCP Client, UDP Client, UDP Server, and HTTPD Client modes. DHCP support can simplify address assignment, while DNS, webpage-based configuration, and network firmware upgrades make the unit more manageable than a bare protocol converter.
For reliability, the product supports a heartbeat package mechanism, custom registration packages, and virtual serial port software. TCP Server mode can accommodate between one and 16 clients, with four as the default. These functions go well beyond the basic purpose of a passive adapter, but they also mean the user must understand ports, network addressing, serial settings, and the communication model required by the attached equipment.
This is the best choice in the guide when the objective is to make an RS232 device available to software on an IP network. It suits industrial controls, monitoring systems, and legacy equipment that cannot be moved close to the host computer. It is not the simplest solution for a short serial extension, and network exposure should be considered carefully when configuring remote access.
Turns Serial into Network Communication
Unlike a coupler that merely carries RS232 voltage levels through an RJ45 cable, this module handles the network side of the connection. A connected device can communicate through TCP or UDP according to the selected operating mode.
Flexible Modes for Different Systems
Multiple client and server modes let the unit fit central software, individual device connections, or request-response arrangements. Virtual serial port support also provides a route for locally installed applications that expect a conventional serial port.
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7. DTECH RS232 Active Converter – Protected Long-Haul Conversion
DTECH RS232 Active Converter
RS232 to RS485 conversion
RS422 four-wire operation
600W surge protection
15KV ESD protection
Automatic baud detection
This DTECH active converter changes bi-directional RS232 signals into RS485 or RS422. Its 4.7 rating places it among the strongest products in the guide, and the combination of signal conversion, protection, status indicators, and a 115200-bps maximum rate makes it much more capable than a passive DB9 coupler. It is designed for long-haul serial data communication.
Pros
- Converts to RS485 and RS422
- Provides substantial surge protection
- Includes AC-to-DC power supply
- TX, RX, and power indicators
- Automatic baud-rate adjustment
Cons
- Requires external power
- Not an Ethernet protocol gateway
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The converter supports two-wire half-duplex RS485 and four-wire full-duplex RS422, including point-to-point and point-to-multipoint arrangements with up to 32 protocol devices. Built-in collision protection improves data handling, while automatic baud-rate detection and adjustment reduce configuration effort. The DB9 side connects to RS232 equipment, and the other side can terminate at either a Phoenix terminal block or RJ45 network port.
Protection is a major reason to consider this product. The RS485 or RS422 link is listed with 600W lightning surge protection, while the RS232 side includes 15KV static protection. A 110/240V AC-to-9V DC power supply is included, and TX, RX, and power LEDs give a quick visual indication of operation. Since the unit is active, it requires power and introduces more configuration considerations than a passive adapter.
It is well suited to industrial equipment, long cable runs, and systems that need to bridge older RS232 controllers with modern RS485 or RS422 infrastructure. The choice between half-duplex and full-duplex modes must match the target network, and the included power supply should be installed according to local electrical requirements. This is a conversion tool, not an IP gateway.
Electrical Protection for Industrial Links
Surge and static protection provide added confidence in installations where long cables may encounter electrical transients. These protections are particularly relevant when RS232 equipment communicates with distributed RS485 or RS422 devices.
Visible Operating Status
Dedicated TX, RX, and power indicators make basic troubleshooting faster. Technicians can immediately see whether the unit is powered and whether communication activity is being sent or received.
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8. LINOVISION Dual-Port Gateway – Remote Industrial Monitoring
LINOVISION Dual-Port Gateway
RS232 and RS485 ports
Modbus RTU/TCP conversion
Sixteen-host multi-polling
IP30 industrial enclosure
The LINOVISION dual-port gateway combines RS232 and RS485 connectivity with Ethernet-based monitoring and control. Its 4.1 rating makes it a credible choice for industrial and commercial networks, especially where a Modbus RTU/TCP translation layer is needed. Unlike a passive cable adapter, it actively integrates serial devices with a network infrastructure.
Pros
- Combines RS232 and RS485
- Translates Modbus protocols
- Supports remote monitoring
- Wall and rail mounting options
- Wide operating temperature range
Cons
- Designed around Modbus workflows
- Cloud feature requires configuration
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The gateway supports Modbus RTU/TCP conversion, allowing serial and network Modbus systems to exchange data transparently. Multi-host polling accommodates as many as 16 hosts, which is useful for centralized software that must query several field devices. Typical application areas include POS equipment, agricultural sensors, PLCs, and medical devices used for remote monitoring and control.
Its industrial enclosure has an IP30 protection rating and a wide stated operating range from -40°F to 185°F. Both wall and rail mounting are supported, making it practical for control cabinets and equipment rooms. The free Linovision AIoT RemoteMonit service covers up to 30 managed devices, while larger fleets or customized functions require further arrangements.
This gateway is most appropriate for users who need protocol conversion and remote visibility rather than a simple serial extension. Configuration should be checked against the Modbus implementation used by the attached equipment, particularly for device addressing, polling, and serial parameters. Buyers seeking a general-purpose RS232 adapter will find the additional functionality unnecessary, but facility operators with distributed serial devices gain a more complete network bridge.
Unified Access to Mixed Serial Equipment
Having both RS232 and RS485 in one unit can simplify a control cabinet that contains different device types. The gateway allows those systems to participate in a common Modbus-based network workflow.
Built for Equipment Environments
Rail or wall mounting and a wide temperature range suit installations away from a comfortable office environment. These physical features matter when the gateway is positioned near industrial or outdoor-adjacent equipment.
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9. FT231XS USB Serial Cable – Device-Specific PC Connectivity
FT231XS USB Serial Cable
USB to RJ45 serial
Six-foot integrated cable
FT231XS bridge chipset
USB 2.0 computer connection
This six-foot USB-to-RJ45 RS232 cable is designed primarily for Voltronic EG4 6000EX and 6500EX equipment, with the listing also referencing compatible applications such as Axpert, Kodak, Mecer, Solar Phocos, and RCT devices. Its 4.6 rating reflects a well-regarded solution for users who need to connect one of the supported systems to a modern computer.
Pros
- Direct computer serial connectivity
- Integrated six-foot cable
- Supports listed inverter models
- Uses familiar USB connection
- Recognized bridge chipset
Cons
- Intended for specific devices
- May require FTDI driver
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The cable combines a USB 2.0 computer connection with an RJ45 serial connection to the target equipment. An FT231XS bridge chipset handles the interface, and the integrated cable measures 180 centimeters, or six feet. This arrangement is more specialized than the passive DB9 adapters because it creates a serial port through USB rather than simply extending DB9 wiring over a network cable.
Software support is an important consideration. The instructions recommend downloading and installing the FTDI Virtual COM Port driver from FTDI's official website if the system does not detect the device automatically. A working driver allows compatible applications to communicate through a virtual serial port, but the included software and settings must match the attached equipment.
This cable is best for a technician servicing a listed inverter or compatible device that lacks a convenient PC connection. It is not a universal RS232-to-RJ45 extender, a DB9 gender adapter, or an Ethernet gateway. Confirm the target model and communication requirements before buying. For that use case, its integrated six-foot design and direct USB connection reduce the number of separate components.
Convenient Link from a Modern Computer
USB provides a familiar connection method for computers that no longer include a physical serial port. The integrated cable avoids searching for a separate USB-to-serial adapter and a separate RJ45-to-device lead.
Best Matched to Listed Equipment
The product is designed around particular Voltronic and related equipment. Confirming device compatibility before installation will prevent unnecessary driver and communication troubleshooting.
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10. DB9 Male and Female Pair – Durable Ready-Made Extension
DB9 Male and Female Pair
Matched male-female pair
65-foot maximum distance
Double-shielded contacts
No external power
This matched DB9 male and female adapter pair is designed to extend RS232 serial data over Cat5, Cat5E, or Cat6 cable. Its 5.0 rating is the highest numerical rating in the list, although ratings should still be considered alongside connector compatibility and installation requirements. The pair offers a ready-made solution for extending a serial link by as much as 65 feet.
Pros
- Highest customer rating
- Includes matching end adapters
- Molded strain relief design
- Nickel-plated oxygen-free contacts
- Ready for plug-and-play use
Cons
- Only extends RS232 serial data
- Not a console or network adapter
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Construction details are a notable strength. Molded strain relief supports repeated plugging and unplugging, grip treads make the connectors easier to handle, and screws secure the DB9 connection. The nickel-plated, oxygen-free copper contacts are described as double-shielded to minimize crosstalk and suppress noise. The product requires no external power, making setup straightforward.
Users must use the male and female components together for the stated extension arrangement, and the installed cable must use the expected pin mapping. The listing describes bi-directional transmission between DB9 ports, but it also clearly states that the product is only for extending RS232 serial data. It is not a console adapter and should not be expected to create standard TCP/IP network connectivity merely because Cat5 or Cat6 cable is used.
The pair is well suited to legacy printers, barcode printers, POS equipment, routers, projectors, monitors, TVs, and other standard nine-pin serial devices. It is a good option for users who want a complete two-end solution rather than purchasing couplers separately. Test the complete path with the intended baud rate and both attached devices before securing the cable in place.
Built for Repeated Connections
Molded strain relief, grip treads, and screwed shells improve handling in service environments. These mechanical details can be more valuable than extra specifications when an adapter is installed and removed regularly.
Ready-Made Two-End Solution
The included male and female pieces remove the need to determine which adapters are needed for a standard extension. Together they form a simple, power-free path over standard twisted-pair cable.
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Buying Guide – How to Choose the Best RS232 to RJ45 Converter
The correct converter depends on the signal path, equipment connectors, communication distance, and environmental demands. Start by deciding whether you need passive extension, active protocol conversion, or full Ethernet gateway functionality.
Determine Whether You Need Extension or Conversion
Choose passive extension for a direct serial connection, active conversion for different electrical standards, and a gateway for networked communication.
Match Every DB9 Connector
Confirm host gender, target gender, and pin mapping before ordering. Buying the wrong connector combination is one of the most common installation errors.
Understand the Distance Rating
Use the shortest practical cable run and test under operating conditions. Longer or noisier environments may require active conversion, better cable, or a professionally installed network gateway.
Check the Signal Type
Never rely on the RJ45 shape alone to infer compatibility. Verify the electrical standard, baud rate, grounding method, and network topology on both devices.
Decide Whether Ethernet Is Actually Required
Choose a network gateway for remote IP access; choose a passive adapter for a direct point-to-point extension.
Consider Power and Protection
Favor protection in electrically noisy installations. Keep powered equipment on a suitable supply and verify voltage requirements before connection.
Review Device Compatibility
Check the device manual for connector type, pinout, and serial settings. Specialized hardware should be purchased only after confirming the exact supported model.
Plan for Installation and Maintenance
Prioritize secure connectors, clear status indication, and serviceable installation. A stable physical setup often matters more than unneeded advanced features.
How to Use and Care for Your RS232 to RJ45 Converter
Begin by disconnecting power from any equipment that will be connected and identifying the DB9 gender, serial standard, pinout, and baud rate at both ends. For a passive extension, select compatible male and female adapters and verify that their wiring matches the equipment manual. Do not connect the adapter to a 15-pin VGA port or assume that an RJ45 socket creates network connectivity.
Attach the adapters securely, route the twisted-pair cable without sharp bends, excess tension, or close parallel runs with noisy power wiring, and connect the serial devices. Power an active converter or gateway and configure the serial parameters, network address, transmission mode, and protocol as required. For a gateway, select TCP Server, TCP Client, UDP, or the required operating mode and use a connection test to confirm data exchange.
Test the link with a short cable first, then move to the final run while checking received and transmitted data. Look for stable readings rather than merely the presence of a recognized port. Secure thumbscrews, avoid repeatedly pulling on the cable, and keep passive couplers away from moisture or conductive debris. For powered equipment, use the specified supply and inspect connectors periodically for looseness, heat, corrosion, or damaged shielding.
Frequently Asked Questions
Does an RS232 to RJ45 adapter create an Ethernet connection?
Not necessarily. Most passive DB9-to-RJ45 products only carry RS232 signals across twisted-pair cable and do not provide an IP address or network protocol. A true serial-to-Ethernet gateway, such as the USR-TCP232-302, performs that conversion and must be configured for network communication.
Which DB9 gender combination should I choose?
Match the adapter to the connectors on both devices. A male-to-female pair is commonly used for a male DB9 host and female DB9 peripheral, while a female-to-female arrangement suits two female endpoints. The correct choice also depends on the pin mapping, so checking both device manuals is essential.
Can Cat5 or Cat6 cable carry RS232 signals?
Yes, passive adapters can route RS232 through twisted-pair cable when the conductors are connected to the correct pins. The cable becomes a serial extension rather than an Ethernet link. Length, baud rate, grounding, shielding, and electrical interference determine whether the connection remains reliable.
How far can an RS232-to-RJ45 extension run?
The products in this guide state different maximum distances, generally up to 65 feet for common passive couplers and up to 100 feet for one multi-pack. Actual performance depends on the cable and equipment. For longer or more demanding runs, an active RS485, RS422, or Ethernet solution may be more appropriate.
Do I need external power for these converters?
Passive DB9-to-RJ45 couplers do not require external power because they do not regenerate or translate the signal. Active RS232-to-RS485 or RS422 converters and serial-to-Ethernet gateways do require power. The DTECH active converter includes a suitable 110/240V AC-to-9V DC supply.
Can I use a DB9-to-RJ45 adapter with a VGA port?
No. These adapters are intended for standard nine-pin D-sub RS232 devices and are not compatible with 15-pin VGA connectors. Their RJ45 side is being used for twisted-pair serial wiring, not video, unless a separate purpose-built converter is installed.
Why does my computer not detect the USB serial cable?
The FT231XS USB-to-RJ45 cable may require the FTDI Virtual COM Port driver, which should be obtained from FTDI's official website. After installation, confirm that the computer assigns a COM port and that the application uses the same port number and serial settings as the attached equipment.
Should I choose an RS232, RS485, or RS422 converter?
Choose RS232 for a direct link between compatible nine-pin serial endpoints, RS485 for two-wire half-duplex networks, and RS422 for four-wire full-duplex links. The target equipment's documentation should determine the required standard. A converter cannot safely operate correctly when the electrical protocols and topology do not match.
Final Thoughts on Choosing the Best RS232 to RJ45 Converter
The DTECH female adapter is a straightforward choice for a basic passive extension, while the DTECH male-and-female kit is the most convenient all-around set for point-to-point work. The USR-TCP232-302 stands apart when the real goal is to connect an RS232 device to TCP/IP infrastructure rather than merely extend a serial cable.
Prioritize the actual connection requirement before focusing on connector shape. Check DB9 gender, signal standard, pinout, distance, power, protection, and operating mode. Passive couplers are best for simple serial links, active converters suit RS485 and RS422 networks, and gateways are necessary for IP-based monitoring or control.
Finally, check the current product listing, price, availability, included accessories, and device compatibility at the time of purchase. Product configurations and retailer offers can change, and the information in this guide is intended to help narrow the field before making the final purchase.