StarTech PEX1S1P950 PCIe Serial and Parallel Combo Expansion Card

Overview

The StarTech PEX1S1P950 is a single-slot PCI Express x1 card that restores legacy I/O to modern systems — giving you one RS-232 serial port (DB-9) and one IEEE 1284 parallel port (DB-25) from a single low-profile-compatible standard card. If your workstation or server chassis no longer has native COM or LPT ports but you're running legacy industrial equipment, label printers, or serial-controlled devices that won't die, this is the direct solution. No USB adapters, no converter chains, no latency penalties — just a clean, bus-native port on the PCIe 2.0 lane.

The card is built around the StarTech expansion card lineup and sits in the broader category of PCIe expansion cards used by IT architects and automation engineers to bridge modern server hardware with legacy peripheral infrastructure.

Key Features

• Asix AX99100 Chipset: The AX99100 is a well-supported multi-function PCIe bridge chip with broad OS driver availability. In practice, that means less time hunting drivers for Windows Server, Linux, or embedded OS builds — a genuine time saver when you're commissioning a rack of systems.
• RS-232 Serial at up to 921.6Kbps: Most legacy COM port applications run well under 115.2Kbps, but the PEX1S1P950 supports up to 921.6Kbps — useful for higher-throughput serial devices like barcode scanners, industrial controllers, or serial-controlled access control hardware that can negotiate faster baud rates.
• 256-Byte FIFO Buffer: The onboard 256-byte FIFO on the serial channel reduces CPU interrupt load by batching incoming characters. In polling-heavy or multi-tasking environments, this keeps serial data from being dropped during OS context switches — something a simple USB-to-serial adapter often can't guarantee.
• IEEE 1284 Parallel at 2.5Mbps: Full IEEE 1284 compliance means the parallel port operates in all standard modes (SPP, EPP, ECP), which matters if you're driving older parallel-port label printers or test equipment that requires EPP/ECP negotiation. The 2.5Mbps throughput is sufficient for any compliant parallel peripheral.
• Full Serial Configuration Flexibility: The DB-9 serial port supports 5, 6, 7, 8, and 9 data bits; stop bits of 1, 1.5, or 2; parity modes of None, Odd, Even, Space, and Mark; and flow control via None, XON/XOFF, or RTS/CTS. This covers virtually every legacy serial device configuration you'll encounter in the field without any workaround.
• PCIe 2.0 x1 Interface: Slots into any PCIe x1, x4, x8, or x16 slot — the card only uses one lane, so it's flexible in chassis with limited open x1 slots. PCIe 2.0 compatibility ensures backward and forward slot compatibility across generations.
• Standard Profile Form Factor: At 3.7 x 3.1 inches and 2.2 oz, this is a standard-profile card. It fits full-height desktop and tower workstation cases. If you're targeting a 1U or 2U rack chassis with low-profile slot requirements, verify the chassis height — a low-profile bracket option may need to be confirmed with StarTech.
• Extended Operating Temperature Range (-40°C to 85°C): Industrial-grade thermal tolerance means this card won't throttle or fault in uncontrolled environments — relevant for edge servers in warehouse automation or manufacturing floors where ambient temperatures swing well beyond office norms.
• Lifetime Warranty: StarTech backs the PEX1S1P950 with a lifetime warranty, which removes the card from your hardware refresh cycle planning — one less component to budget for replacement.

Integration and Compatibility

The PEX1S1P950 integrates into any PCIe 2.0-capable motherboard and is driver-supported across major operating systems via the AX99100 chipset. The DB-9 serial port is a standard DE-9 male connector compatible with RS-232 serial cables used across industrial automation, access control panels, point-of-sale terminals, and serial-controlled surveillance or building management hardware. The DB-25 parallel port follows IEEE 1284 signaling, making it compatible with legacy parallel printers and test instruments. If you're connecting to a PoE-managed network environment alongside legacy serial-controlled devices — common in hybrid security and automation deployments — this card handles the serial side without consuming a USB port on your host system. For label printing environments, pairing this card with industrial label printers that use parallel interfaces extends the useful life of that hardware. Consult your PCIe expansion card selection guide if you need additional ports beyond what this single-card solution provides.

Frequently Asked Questions

Q: Does the PEX1S1P950 work in a low-profile (half-height) chassis?

A: The PEX1S1P950 ships as a standard-profile card. If your chassis requires a low-profile bracket, confirm with StarTech whether a compatible bracket is available for this model before ordering.

Q: What is the maximum baud rate supported on the serial port?

A: The RS-232 serial port on the PEX1S1P950 supports a maximum baud rate of 921.6Kbps, well above the 115.2Kbps needed by most legacy devices.

Q: What parallel port modes does the PEX1S1P950 support?

A: The parallel port is IEEE 1284 compliant, which covers all standard modes including SPP, EPP, and ECP. This covers the full range of legacy parallel-port peripherals including printers and measurement equipment.

Q: What chipset does the PEX1S1P950 use, and why does it matter for driver support?

A: The card uses the Asix AX99100 chipset, which has broad native driver support across Windows, Linux, and other operating systems. This reduces driver sourcing friction in both fresh deployments and OS migrations.

Q: What is the warranty on the PEX1S1P950?

A: StarTech covers the PEX1S1P950 with a lifetime warranty.

Q: Can this card handle industrial environments with temperature extremes?

A: Yes. The PEX1S1P950 is rated for operating and storage temperatures of -40°C to 85°C, making it suitable for edge server deployments in warehouses, manufacturing floors, and other environments with uncontrolled ambient temperatures.

James Everett

The spec I keep coming back to on the PEX1S1P950 is the 256-byte FIFO buffer on the serial channel. In environments where you're running serial-controlled access panels or industrial PLCs alongside a multitasking OS, that buffer is what keeps you from dropping characters during a context switch — something I've seen bite integrators who went with cheap USB-to-serial adapters instead of a bus-native card like this one.

Technical Highlights:

• 921.6Kbps Max Baud Rate: Eight times faster than the 115.2Kbps ceiling most people associate with RS-232 — headroom that matters when connecting higher-speed serial controllers that can negotiate above standard rates.
• IEEE 1284 Parallel at 2.5Mbps: Full mode compliance (SPP/EPP/ECP) means the DB-25 port negotiates correctly with legacy parallel printers and instruments — not just a basic SPP passthrough.
• -40°C to 85°C Operating Range: Industrial thermal tolerance in a standard PCIe card is uncommon at this price point; it's directly relevant for edge servers installed in unheated or poorly climate-controlled spaces.

Deployment Considerations:

• The card is standard-profile only as shipped — verify your chassis slot height before ordering if you're targeting a 1U or 2U rack enclosure; a low-profile bracket may be needed and should be confirmed with StarTech.
• The AX99100 chipset has good Linux kernel support, but on older Linux builds (pre-4.x kernels) you may need to manually load the ax99100 module — worth testing in a staging environment before a wide rollout.

This card earns its place in warehouse automation and manufacturing edge server builds where a single PCIe slot needs to support both a serial-controlled device (access panel, barcode terminal, PLC) and a legacy parallel printer simultaneously — with no USB converters in the chain to introduce latency or driver instability.