PCIE-SE2 Dual RS-232 Card
4.5Editor score
Two RS-232 DB9 ports
PCIe x1 physical interface
Full and low-profile brackets
In this guide
A Pcie Serial Port Card adds legacy DB9 RS-232 connections to a modern computer, making it useful for POS systems, industrial controllers, scanners, printers, and other serial equipment. A strong choice should match your port count, operating system, case design, connector requirements, and device communication speed.
This guide compares ten expansion cards based on their supplied specifications, including UART controller, RS-232 port count, supported platforms, bracket options, data-rate claims, driver requirements, and intended applications. The list covers single-port and dual-port designs as well as a combined serial and parallel adapter.
Each review explains where a card is strongest, where its installation requirements matter, and which types of users may prefer it. Product ratings and availability can change over time, and current prices should be checked at the linked listings before making a purchase.
Top 3 Picks for Best Pcie Serial Port Card
StarTech PEX2S953LP
4.9Editor score
Two 16950 UART ports
Up to 921.6 Kbps
Per-port power configuration
StarTech PEX1S953LP
4.2Editor score
Single RS-232 DB9 port
16950 UART controller
Configurable pin-nine power
Top 10 Best Pcie Serial Port Card in 2026 Compared
The comparison below highlights the most important differences among these ten cards, including port count, controller type, platform support, included brackets, and advertised communication capabilities.
ProductsSpecificationsEditor scorePrice
Best Budget
PCIE-SE2 Dual RS-232 Card
Two RS-232 DB9 ports
ASIX AX99100 controller
Windows and Linux support
Full and low-profile brackets
4.5Editor score
Editor's Choice
StarTech PEX1S953LP
One RS-232 DB9 port
16950 UART controller
Up to 921.6 Kbps
Windows and Linux support
4.2Editor score
Best Premium
PCIE-SE2 Dual DB9 Card
Two RS-232 DB9 ports
ASIX AX99100 controller
256-byte transmit FIFO
Full and low-profile brackets
4.5Editor score
StarTech PEX2S953LP
Two RS-232 DB9 ports
16950 UART controller
Up to 921.6 Kbps
Per-port power configuration
4.9Editor score
StarTech PEX2S1050
Two DB9 serial ports
PCI Express 1.0a compliant
Up to 460 Kbps
Plug-and-play operation
4.2Editor score
WCH382 Combo Serial Parallel Card
Serial and parallel ports
WCH382 controller
Up to 1.5 Mbps parallel
Windows and Linux support
4.3Editor score
AX99100 Dual Serial Card
Two RS-232 DB9 ports
ASIX AX99100 controller
256-byte transmit FIFO
Two low-profile brackets
3.7Editor score
VANTEC Dual RS-232 Card
Two RS-232 ports
PCI Express host card
Dual-port configuration
Compact expansion format
5.0Editor score
WCH382 Dual Serial Card
Two RS-232 DB9 ports
Two 16C550 UARTs
Up to 230400 Bps
Low-profile bracket included
4.2Editor score
MCS9922 Single Serial Card
One RS-232 DB9 port
MCS9922 controller
Up to 250 Kbps
Low-profile card format
4.3Editor score
1. PCIE-SE2 Dual RS-232 Card – Best Overall Pcie Serial Port Card
PCIE-SE2 Dual RS-232 Card
Two independent RS-232 ports
ASIX AX99100 controller
256-byte transmit FIFO
PCIe x1 interface
The PCIE-SE2 is a dual-port PCI Express RS-232 card built around the ASIX AX99100 solution, and it holds a 4.5 rating. Its combination of two DB9 connectors, broad platform coverage, and support for both standard and low-profile systems makes it a practical general-purpose option for adding serial connectivity to a desktop or industrial computer.
Pros
- Two ports in one card
- Broad Windows compatibility
- Linux source-code support
- Both bracket styles included
- Suitable for many industries
Cons
- Requires driver installation
- Low-profile bracket needs manual fitting
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Both ports are presented as independent RS-232 connections, allowing one card to serve two serial devices or separate port assignments within the host system. The controller includes a 256-byte transmit FIFO and works with Intel, AMD, and ARM hardware platforms. It uses a PCIe x1 physical interface while remaining compatible with x1, x4, x8, and x16 slots, which gives buyers flexibility when choosing a larger expansion slot.
The main inconvenience is that this is not a completely driverless card. Installation requires the appropriate driver from the included mini-CD for supported Windows versions. Linux support is more technical: users working with kernel 2.6.x through 5.x are directed to compile source code from the driver CD. Slim-PC owners must also replace the full-size bracket by hand. These requirements are clearly stated, so they are predictable rather than hidden drawbacks.
This card is a strong recommendation for a technician, small business, or home user who needs two serial ports without adding two separate expansion cards. It also suits anyone restoring a desktop for scanners, POS equipment, industrial controls, security systems, or legacy printers. For the broad mix of compatibility, included brackets, and capable controller, it is the strongest overall value-oriented selection in this list.
Two Ports Simplify System Expansion
A dual-port design reduces the need for multiple adapters and gives a host two DB9 connections in one expansion slot. That makes the card especially convenient for connecting paired serial devices or separating application traffic across ports.
Useful Platform and Bracket Flexibility
Compatibility with x1 through x16 physical slots and the supplied standard and low-profile brackets broadens the range of desktop and industrial cases it can serve. Driver selection remains essential, however, particularly for Linux configurations.
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2. StarTech PEX2S953LP – Best Feature-Rich Dual-Port Card
StarTech PEX2S953LP
Two 16950 UART ports
Up to 921.6 Kbps
256-byte FIFO buffer
Per-port pin-nine power
The StarTech PEX2S953LP is a two-port PCIe RS-232 adapter with a 4.9 rating, the highest among the products compared. It uses a 16950 UART based on the ASIX AX99100 controller, provides a 256-byte FIFO buffer, supports a ninth data bit, and advertises bidirectional RS-232 communication at up to 921.6 Kbps per port.
Pros
- Highest listed rating
- High advertised port speed
- Independent power settings
- Both brackets included
- Broad industrial applications
Cons
- Two ports share power capacity
- Linux use may need configuration
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Its most distinctive feature is configurable power on pin 9. Each port can be set independently to 12 volts, 5 volts, or no power, with total current not exceeding 2 amps. This is useful when connected equipment expects a particular signal on the ninth pin, although users should verify the requirements of both attached devices before configuring the outputs.
The card includes a preinstalled low-profile bracket and a separate full-profile bracket, giving it more installation flexibility than options that include only one bracket style. It supports Windows XP and later systems as well as Linux. The listed uses span point-of-sale terminals, PLCs, factory automation, scientific sensors, medical equipment, scanners, and oscilloscopes, reflecting a card designed for diverse professional serial workloads.
The principal limitation is that the power configuration is shared within a 2-amp total, and the highest data-rate figure is an advertised maximum rather than a guarantee for every attached device or cable. Even so, the card's high rating, 16950 controller, flexible power handling, and two-port design make it an excellent choice for demanding users who want room to configure connected serial equipment.
Configurable Power Adds Equipment Flexibility
Independent 12-volt, 5-volt, or unpowered pin-nine settings can accommodate serial devices with different signaling expectations. The combined current limit means both ports should be checked against the total power requirement of the connected hardware.
High-Speed 16950 UART Capability
The 16950 UART, 256-byte FIFO, ninth-bit support, and advertised rate of up to 921.6 Kbps give the card a more advanced feature set than many simpler dual-port alternatives. Those characteristics make it relevant to demanding industrial and diagnostic setups.
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3. StarTech PEX1S953LP – Best Configurable Single-Port Card
StarTech PEX1S953LP
One 16950 UART port
Up to 921.6 Kbps
Configurable pin-nine power
Low-profile bracket included
The StarTech PEX1S953LP is a single-port PCIe RS-232 card with a 4.2 rating. It is built around a 16950 UART based on the ASIX AX99100 controller, includes a 256-byte FIFO buffer, supports a ninth data bit, and advertises bidirectional communication at up to 921.6 Kbps through its DB9 port.
Pros
- Advanced 16950 controller
- Configurable pin-nine power
- High advertised data rate
- Both case profiles supported
- Windows and Linux compatible
Cons
- Only one serial connector
- Shared current limit applies
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As with StarTech's dual-port model, pin 9 can be configured for 12 volts, 5 volts, or no power, with total output limited to 2 amps. For a single attached serial device, this gives the card more signaling flexibility than a typical basic adapter. The card also supports Windows and Linux and is intended for use in standard- or low-profile desktop and server systems.
Both a low-profile and full-profile bracket are included, which addresses a common source of installation problems with expansion cards. The trade-off is that a one-port design may be less convenient if the computer already serves two serial devices. Its power option also requires care: even when only one port is present, the total current across pin-nine outputs must remain within the stated limit.
This is the premium-oriented option for a user who values controller sophistication, configurable pin-nine power, and flexible mounting over having two connectors. It is especially suitable for one carefully selected device that needs reliable RS-232 communication and specific power signaling. Users who expect future expansion should instead consider the dual-port PEX2S953LP.
One Port, Advanced Serial Features
The PEX1S953LP avoids unnecessary port duplication while retaining the 16950 UART, FIFO buffering, ninth-bit support, and high advertised data rate. That balance makes it well suited to dedicated equipment connections.
Bracket Options Reduce Fitment Risk
A preinstalled low-profile bracket and an included full-profile bracket allow installation in more cases than a fixed-format card. Buyers should still measure clearance around the bracket and adjacent ports.
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4. PCIE-SE2 Dual DB9 Card – Best Versatile Linux-Compatible Option
PCIE-SE2 Dual DB9 Card
Two independent RS-232 ports
ASIX AX99100 controller
256-byte transmit FIFO
Windows and Linux support
The Dual Port PCI Express RS-232 DB9 card combines two independent serial connections with a 4.5 rating. It uses the ASIX AX99100 controller, includes an on-chip 256-byte transmit FIFO, and supports Intel, AMD, and ARM hardware platforms. Its overall design closely resembles the PCIE-SE2, making it another practical option for adding DB9 connectivity.
Pros
- Dual independent serial ports
- Strong platform coverage
- Fits multiple PCIe slot sizes
- Two bracket configurations
- Broad hardware-platform support
Cons
- Windows driver required
- Linux compilation is technical
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Compatibility extends across Windows XP, Vista, 7, 8.x, 10, and 11 in both 32-bit and 64-bit forms. Linux kernels 2.6.x through 5.x are supported through source code on the driver CD, which requires users to compile the driver rather than relying only on automatic installation. The card follows a PCIe x1 physical design but can be used in x1, x4, x8, and x16 slots.
Its standard full-size bracket and included low-profile bracket provide installation flexibility, particularly for 2U systems. The low-profile bracket must be fitted manually. As with the PCIE-SE2, the lack of a purely plug-and-play setup adds an installation step, and buyers may need to obtain the supplied driver media after the original package has been separated from its computer.
The card suits users with two serial devices who need broad operating-system coverage and flexible mounting. It is a compelling alternative when the PCIE-SE2 is unavailable, when a buyer prefers this particular listing, or when its bracket arrangement better matches the target system. It may be less attractive to someone who wants effortless driver installation or who works primarily in a Linux environment without confidence in compiling kernel drivers.
Independent Ports for Paired Equipment
The two independent RS-232 connections allow simultaneous use with separate DB9 devices. This is useful in control rooms, service benches, and legacy industrial systems that need more than one serial channel.
Broad CPU Platform Coverage
Support for Intel, AMD, and ARM platforms makes the card less dependent on a particular processor family. The available operating-system driver is still the decisive compatibility factor.
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5. StarTech PEX2S1050 – Best Simple Installation Choice
StarTech PEX2S1050
Two DB9 serial ports
Up to 460 Kbps
IRQ sharing support
Plug-and-play connection
The StarTech PEX2S1050 is a dual-port PCIe serial card with a 4.2 rating and a straightforward installation proposition. It offers two DB9 connectors, plug-and-play connection, automatic resource handling, and IRQ sharing, reducing some of the configuration work associated with adding legacy serial ports.
Pros
- Straightforward installation
- Two serial connectors
- IRQ sharing supported
- Broad PCIe slot compatibility
- Standard and low-profile brackets
Cons
- Lower speed than modern alternatives
- No pin-nine power configuration
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The card complies with PCI Express 1.0a and can be installed in 1x, 2x, 4x, 8x, and 16x slots. It supports serial data-transfer rates of up to 460 Kbps, which is lower than the 921.6 Kbps maximum advertised by the newer StarTech 953-series cards. It also lacks the configurable pin-nine power options found on those models.
A standard-profile bracket is installed, while a low-profile bracket is available for compatible systems. This gives the card useful physical flexibility. Its strongest advantage is simplicity: users who want recognized dual-port functionality without the source-code driver process described for some Linux-focused options may find the installation process more approachable.
The PEX2S1050 is best for manufacturing equipment, point-of-sale systems, security devices, and other legacy serial installations that do not need maximum throughput or specialized pin-nine signaling. It is also a sensible pick for standard desktops and servers that need a dependable way to restore two DB9 connections. Users requiring faster advertised rates should examine the 953-series instead.
Plug-and-Play Reduces Configuration Work
Automatic resource selection and IRQ sharing simplify deployment in computers that may already use several expansion devices. This makes the card attractive where reliability and straightforward setup matter more than specialized controls.
Physical Slot Flexibility
Support for x1 through x16 slots makes the card straightforward to introduce into a range of systems. The standard bracket is preinstalled, and the low-profile bracket covers compact installations that have the necessary clearance.
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6. WCH382 Combo Serial Parallel Card – Best Combined Serial-and-Parallel Solution
WCH382 Combo Serial Parallel Card
Serial and parallel interfaces
WCH382 controller
IEEE 1284 parallel modes
PCIe x1 interface
The WCH382 combo card is a unique entry in this comparison because it combines a serial connection with an IEEE 1284 parallel printer port. Its 4.3 rating reflects a solution aimed at users restoring older desktop equipment, particularly systems that need both a DB9 connection and an LPT-style printer interface.
Pros
- Combines two connector types
- Supports five parallel modes
- Automatic IRQ and I/O selection
- Broad legacy OS support
- Low-profile bracket included
Cons
- Requires CH38XDRV driver
- Only one serial port
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The parallel controller supports SPP, PS2, EPP, and ECP modes, with advertised data rates up to 1.5 Mbps. The card uses a one-lane PCIe interface, automatically selects IRQ and I/O resources, and supports IRQ sharing. A low-profile bracket is included for systems that need the alternative mounting format.
Driver installation is required by opening the CH38XDRV file from the supplied CD. The listed operating-system coverage includes 32-bit Windows 2000, XP, 2003 Server, and Vista; 64-bit XP, 2003 Server, Vista, Windows 7, Windows 8, Windows 10, and Windows 11; and Linux. That breadth is useful for mixed or legacy computing environments.
This card is ideal for a technician maintaining a machine with a serial control device and a parallel printer, or for a collector building a functional legacy PC. It is less suitable for someone needing multiple independent serial ports because only one RS-232 connector is provided. Its real value comes from combining connector types that might otherwise require separate adapters.
One Slot for Two Legacy Interfaces
Combining RS-232 and IEEE 1284 ports reduces case clutter and expansion-slot use. It is particularly helpful when restoring a legacy workstation that has both a serial peripheral and a parallel printer.
Multiple Parallel Operating Modes
Support for SPP, PS2, EPP, and ECP gives the parallel section flexibility across different printer and legacy-device requirements. Actual behavior still depends on the attached hardware and its software.
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7. AX99100 Dual Serial Card – Best Multi-Bracket Installation Option
AX99100 Dual Serial Card
Two RS-232 DB9 ports
ASIX AX99100 controller
256-byte transmit FIFO
Two low-profile brackets
The AX99100 dual serial card offers two RS-232 DB9 ports and uses the familiar ASIX AX99100 controller with a 256-byte transmit FIFO. Its 3.7 rating is the lowest among the ten products here, but the underlying specifications still cover many common uses involving POS equipment, industrial control devices, security systems, logistics tools, scanners, and printers.
Pros
- Two independent serial ports
- Broad operating-system support
- Multiple low-profile brackets
- Works across CPU platforms
- Suitable for many device types
Cons
- Lowest listed product rating
- Mini-CD driver required
- Low-profile fitting is manual
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The card supports Windows XP, Vista, 7, 8.x, 10, and 11 in 32-bit and 64-bit configurations, as well as Linux kernels 2.6.x through 5.x. It works with Intel, AMD, and ARM hardware platforms and follows a PCIe x1 interface while fitting x1, x4, x8, and x16 slots.
Its most unusual physical feature is the inclusion of two low-profile brackets in addition to the standard full-size bracket. This can help buyers accommodate different slim-system layouts without ordering another bracket. The trade-off is that the correct bracket still has to be selected and manually fitted, and the mini-CD driver must be installed for desktop use.
The card makes the most sense for users who need two serial connections, have specific slim-PC bracket requirements, and are comfortable installing a driver from the supplied media. Its lower rating suggests it may not have the same level of customer feedback consistency as several alternatives, so buyers should pay particular attention to system compatibility and the quality of the included installation materials.
Two Low-Profile Bracket Options
Including multiple low-profile brackets improves the chance of matching different compact-case layouts. Each bracket should be checked against available clearance before the card is installed.
Broad Industrial Device Coverage
The listed use cases span business, logistics, security, and industrial environments. The two independent RS-232 ports give a host more connection options without requiring a second expansion card.
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8. VANTEC Dual RS-232 Card – Best Minimal-Specification Dual-Port Pick
VANTEC Dual RS-232 Card
Two RS-232 ports
PCI Express host card
Dual-port configuration
Serial expansion interface
The VANTEC 2-Port Serial RS-232 PCIE Host Card has a 5.0 rating, making it the highest-rated listing in the group. Its defining feature is a simple, focused design: two RS-232 serial ports delivered through a PCI Express host card for users who need to restore or add serial connectivity.
Pros
- Perfect listed rating
- Two serial connectors
- Simple expansion-card format
- Focused RS-232 functionality
Cons
- Sparse supplied specifications
- No detailed OS details
- No bracket information
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The supplied product information is brief and identifies the card as a two-port RS-232 PCIe host card without listing its controller, data rate, supported operating systems, driver method, or included brackets. That limited documentation makes this option harder to compare in fine detail than the other cards, several of which list detailed Linux support, FIFO sizes, UART types, and mounting options.
The 5.0 rating indicates a highly favorable customer response, but it should not be treated as evidence of features that are not stated. Buyers who need certainty about driver compatibility, operating-system support, or physical clearance should consult the current listing and manufacturer information before ordering. It is also worth confirming whether the DB9 connector arrangement and any included bracket fit the intended computer.
This card is a reasonable candidate for a straightforward two-port RS-232 requirement, particularly for a buyer who prioritizes its strong listed rating and uncomplicated dual-port format. It is better suited to users who can independently verify platform support than to demanding industrial buyers who need documented UART specifications, flow-control details, or explicit bracket options.
Straightforward Two-Port Connectivity
The card focuses on adding two RS-232 connections through PCIe. That narrow objective can be attractive when the installation requires standard serial ports and no additional parallel interface.
Verify Details Before Purchasing
Because the supplied listing contains minimal technical detail, buyers should confirm operating-system support, driver requirements, connector layout, and bracket dimensions. Clear expectations are especially important for industrial or service installations.
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9. WCH382 Dual Serial Card – Best WCH382-Based Dual-Port Alternative
WCH382 Dual Serial Card
Two RS-232 DB9 ports
Two 16C550 UARTs
Up to 230400 Bps
PCIe x1 interface
The WCH382 dual serial card uses a WCH382 chipset and two 16C550 Fast UART serial ports. Its 4.2 rating and advertised transfer rate of up to 230400 Bps position it as a straightforward dual-RS-232 solution for legacy and industrial equipment rather than a high-speed serial platform.
Pros
- Two dedicated UART channels
- Automatic resource selection
- IRQ sharing supported
- Broad legacy OS support
- Low-profile bracket included
Cons
- Lower maximum data rate
- CH38XDRV driver required
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The card automatically selects IRQ and I/O address and supports IRQ sharing, helping it fit into a system that already contains multiple expansion devices. It follows the ExpressCard/34mm form factor and uses a one-lane PCIe interface. A low-profile bracket is included, which improves its usefulness in compact systems that have the required space.
Windows 32-bit systems including 2000, XP, 2003 Server, and Vista are listed, along with 64-bit XP, 2003 Server, Vista, Windows 7, Windows 8, Windows 10, and Windows 11. Linux is also listed as supported. Installation involves opening the CH38XDRV file from the included CD, so this is not a zero-configuration product even though the card handles resource selection automatically.
The card is a sensible alternative for users who want two industrial-style DB9 ports, especially where the connected equipment operates within the lower advertised transfer rate. It may also appeal to buyers seeking a WCH382-based alternative to ASIX-based cards. Those needing a faster maximum rate, configurable pin-nine power, or 16950 UART features should consider one of the newer 953-series options.
Dedicated UARTs for Two Devices
Two 16C550 Fast UART channels provide separate serial controllers for connected equipment. The design is appropriate for legacy control, monitoring, and data-collection setups that do not require the highest advertised transfer rate.
Automatic Resource Management
Automatic IRQ and I/O selection plus IRQ sharing simplifies integration into a populated desktop. Software installation through CH38XDRV is still required to establish the appropriate driver connection.
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10. MCS9922 Single Serial Card – Best Compact Single-Port Option
MCS9922 Single Serial Card
One RS-232 DB9 port
MCS9922 controller
Up to 250 Kbps
Low-profile form factor
The MCS9922 card is a compact single-port PCIe RS-232 adapter with a 4.3 rating. It uses the MCS9922 chipset, provides one DB9 connection, and includes a 256-byte transmit FIFO. Its low-profile form factor makes it relevant to compact computers and other systems where a full-height card would be difficult to fit.
Pros
- Compact low-profile format
- Hardware and software flow control
- Multiple serial word lengths
- 256-byte transmit FIFO
- PCIe x1 bandwidth
Cons
- Only one serial port
- Modest maximum data rate
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The serial interface is compatible with the industrial 16C550 UART standard, supports both hardware and software flow control, and handles 5-, 6-, 7-, and 8-bit serial formats. It advertises a transfer rate of up to 250 Kbps on the port. That rate is lower than the figures offered by the more advanced dual-port cards, but it remains relevant for many configuration, control, and data-transfer tasks.
Its single-lane PCIe interface is compliant with the PCI Express base specification revision 1.0a and is described as offering throughput up to 2.5 Gbps. The main limitation is straightforward: it offers only one serial connector. A second device would require another adapter or a different multi-port card.
This adapter is a good fit for a compact system that needs one serial connection, flow control, or support for multiple character widths. It may suit retro-computing, industrial maintenance, or legacy-control applications where a small physical footprint matters more than having several ports. For broader connectivity, the dual-port ASIX and WCH382 options provide a more direct path.
Compact Form for Constrained Systems
The low-profile format reduces the physical demands of adding a serial controller. It is a useful option for compact computers, provided the case offers sufficient clearance around the DB9 connector.
Useful Flow-Control Options
Support for both hardware and software flow control gives the user options when managing a serial link. Supporting 5- through 8-bit formats also broadens its relevance for older equipment and custom configurations.
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Buying Guide – How to Choose the Best Pcie Serial Port Card
The right PCIe serial card depends less on marketing language than on direct compatibility with your devices, computer, operating system, and physical installation. Use the following factors to narrow the field before purchasing.
Number of Serial Ports
Begin by counting the number of serial devices that must be connected at the same time. A single-port adapter is sufficient for one DB9 peripheral and may be preferable when space, power, or cost is more important than expansion. A dual-port card provides two independent connections in one PCIe slot, making it more practical for paired sensors, service tools, industrial controllers, or a POS system that needs more than one serial link. Do not count parallel or printer ports as serial connectors; a combined card may include both interfaces.
In short, choose one port for one device and two ports for simultaneous serial equipment.
RS-232 Electrical and Signal Requirements
All of the featured products are described as RS-232 cards, but that broad label does not guarantee identical behavior. Check the DB9 connector arrangement, voltage levels, handshake signals, and pin-nine power expectations of the attached equipment. Some of the StarTech cards provide configurable 12-volt, 5-volt, or no-power options on pin 9, which can be valuable for specific devices. Other cards do not advertise that feature. Cable routing, grounding, and the requirements of long or electrically noisy runs also deserve attention.
Match the card's signal and power options to the equipment, rather than choosing only by connector shape.
UART Controller and Data Rate
The controller determines important capabilities such as buffering, flow control, supported character formats, and maximum serial speed. The ASIX AX99100-based cards use a 16950 UART and advertise up to 921.6 Kbps, while the 16C550-based WCH382 card lists up to 230400 Bps. The MCS9922 card advertises up to 250 Kbps. Most equipment operates far below these maximum figures, so the actual protocol, cable, and device support matter more than the headline rate alone.
Choose a faster controller when supported, but never force a high speed that the attached device cannot handle.
Operating-System and Driver Support
The listed cards support combinations of Windows and Linux, but the installation path varies. Some ASIX-based products require a driver from a mini-CD, and Linux users may need to compile source code for kernels 2.6.x through 5.x. WCH382 products use a CH38XDRV driver file, while the StarTech PEX2S1050 emphasizes plug-and-play behavior and automatic resource selection. Before ordering, check the card against the exact operating-system version, architecture, and kernel used by the target computer.
Verify the driver method first; compatibility claims are not useful if the operating system cannot load the required software.
Physical Slot and Bracket Fit
Most modern desktop cases have PCIe slots, but card dimensions and bracket clearance still matter. Verify that the computer has an available slot, that the card's physical width will fit, and that the ports will not overlap neighboring components. The PCIE-SE2, its dual-DB9 counterpart, and the AX99100 option include low-profile brackets for compact systems. The StarTech 953-series cards include both low- and full-profile brackets, while the MCS9922 is described as low-profile. Some low-profile brackets require manual replacement.
Measure the case and inspect the installed bracket before purchasing, then confirm whether the required alternative is included.
PCIe Lane and Slot Compatibility
A single-lane x1 card normally operates in a larger x4, x8, or x16 physical slot, but this should not be confused with receiving multiple data lanes. The PCIE-SE2 and other AX99100 cards explicitly list compatibility with x1, x4, x8, and x16 slots. The StarTech PEX2S1050 supports 1x, 2x, 4x, 8x, and 16x slots, while the WCH382 and combo designs are described as one-lane PCIe devices. Users should distinguish physical slot width from negotiated PCIe link width and avoid forcing a card into an incompatible connector.
A one-lane card usually fits a wider slot, but confirm physical fitment and the manual's slot requirements.
Application and Equipment Type
General desktop use may require little more than a standard DB9 adapter, while industrial, medical, scientific, and diagnostic systems may place greater importance on stable specifications, flow control, and pin-nine configuration. The PEX2S953LP and PEX1S953LP are attractive when connected equipment has specific power or signaling needs. The MCS9922 is useful where a compact card and one RS-232 link are the priorities. The combo WCH382 option is intended for systems that need both serial and parallel connections.
Match the card's documented features to the exact peripheral, rather than choosing a model that offers features the device cannot use.
Documentation and Support Resources
Cards with detailed OS lists, driver instructions, and mounting details are easier to deploy correctly. The PCIE-SE2 products explain their Windows and Linux requirements and list the supported kernel families, while the StarTech models identify bracket arrangements and supported applications. The VANTEC listing provides less technical detail in the supplied information, so buyers should review the current listing and available documentation. In service environments, clear instructions and dependable driver media can save substantial troubleshooting time.
Prefer a card whose documentation clearly states driver requirements, operating systems, and physical fit.
How to Use and Care for Your Pcie Serial Port Card
Before installation, shut down the computer, disconnect its power, and use appropriate equipment-handling procedures. Confirm that the case has an available PCIe slot and that the card's bracket will fit. Compare the card's DB9 connectors with the serial devices you plan to use, and verify the required operating-system driver, any pin-nine power setting, and the communication parameters expected by each peripheral.
Install the correct driver before or immediately after placing the card, following the instructions supplied for its controller. Once the computer is running, connect only one serial device at a time when possible, then confirm that the system recognizes the new COM port. Test the connection using the device's management software or a terminal utility, and use conservative baud, parity, data-bit, and flow-control settings. Avoid changing several parameters simultaneously, because doing so can make troubleshooting more difficult.
For long-term care, secure DB9 cables so they cannot tug against the card, avoid placing the expansion card near severe heat or sources of electrical interference, and keep dust from accumulating around the bracket and connector. Periodically inspect the screws, cable retention, and connector surfaces. After moving the computer or changing hardware, recheck the seating of the card and reconnect devices before troubleshooting software. If a port stops working, test the cable and another device before assuming the expansion card has failed.
Frequently Asked Questions
What is a PCIe serial port card used for?
A PCIe serial port card adds one or more DB9 RS-232 connections to a computer with a PCI Express expansion slot. It is commonly used with POS terminals, industrial controllers, PLC-related equipment, scanners, security systems, legacy printers, sensors, and service equipment. The card is especially useful when a modern motherboard lacks native serial connectors.
Will a PCIe serial card work in an x16 slot?
Most of the listed cards use a one-lane x1 physical interface, and many explicitly state that they can be installed in x1, x4, x8, or x16 slots. A card will normally operate at the capabilities of its own controller even when installed in a wider slot. Check the card's physical dimensions, bracket clearance, and the motherboard manual before installation.
Do PCIe serial port cards require drivers?
Driver requirements vary by card. Some ASIX-based products require installation from a mini-CD, WCH382 products use a CH38XDRV driver file, and some Linux configurations require compiling supplied source code. The StarTech PEX2S1050 is described as offering plug-and-play connection. Check the operating system, architecture, and installation instructions for the exact card you are considering.
What is the difference between a single-port and dual-port serial card?
A single-port card provides one DB9 serial connection, while a dual-port card provides two. The dual-port model is convenient when two devices must operate at once and may reduce the need for a second expansion card. A single-port model can be sufficient for one device and may fit systems with tighter space or simpler connection requirements.
Can I use a low-profile bracket in a standard desktop?
Usually, a low-profile bracket is intended for compact or slim cases, while a full-height bracket is used in standard cases. Some cards include both, allowing the installer to match the computer's layout. Check the supplied bracket list, compare hole spacing and port position, and ensure the installed connector will not overlap the case or neighboring expansion cards.
Does a faster advertised baud rate make a card better?
Not automatically. The maximum rate is only one part of compatibility, and the connected device, cable, protocol, and software must all support the selected speed. Some industrial or legacy equipment performs best at a lower setting. Choose a faster controller when the equipment can use it, but prioritize correct protocol support and reliable communication over a headline specification.
Are RS-232 and RS-485 the same interface?
No. RS-232 and RS-485 use different electrical signaling, connector arrangements, and communication methods. The products in this guide are described as RS-232 cards with DB9 ports and are not automatically suitable for RS-485 equipment. Verify the exact interface required by your peripheral before purchasing an adapter.
How do I identify the new serial port after installation?
After installing the driver and restarting if required, check the operating system's device or port-management utility. The new adapter should appear as a communications port, often with a COM designation under Windows. If it does not appear, check that the card is seated, the correct driver has been loaded, the operating-system version is supported, and no conflicting device is using the adapter.
Final Thoughts on Choosing the Best Pcie Serial Port Card
The PCIE-SE2 stands out as the strongest overall value-oriented choice because it combines two RS-232 ports, broad Windows and Linux coverage, flexible slot compatibility, and both standard and low-profile brackets. The StarTech PEX2S953LP is the feature-rich selection for buyers who value a 16950 UART, high advertised data rates, per-port pin-nine power settings, and a strong listed rating.
For a single connection with the same advanced StarTech feature set, the PEX1S953LP is the better match. Buyers needing a very simple dual-port installation may prefer the StarTech PEX2S1050, while the MCS9922 serves a compact single-port use case. The combo WCH382 card is the specialized answer when both serial and parallel interfaces are required, and the WCH382 dual serial model offers an alternative controller family.
Before ordering, prioritize exact operating-system support, the number and type of attached devices, DB9 pin requirements, driver installation, and case clearance. Specifications can change by revision, and ratings, availability, and prices also shift over time, so review the current listing and confirm current pricing before purchasing.