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Green PCB PCI card with four DB9 ports on a metal bracket

SIIG, Inc

SIIG, Inc JJ-P45012-S7 4-port PCI serial expansion card

SKU CH-5H2H-V1GK4 MPN JJ-P45012-S7

Adds four 9-pin RS232 serial ports via PCI with 16550 UARTs up to 230Kb/s, IRQ sharing, 32-byte FIFOs, and 5V/12V power output on 3.3V/5V PCI-X slots

  • External connectors2 x Serial Ports
  • Internal ports2 x Serial Ports
  • Product typePCI to Serial Port Card
  • DetailsChip: Oxford OXuPCI954 Bus type: 32-bit PCI Port type: Four
  • Key featuresSupports 32-/64-bit, 3.3 V/5 V PCI and PCI-X slots Four high
  • Add four serial ports via a single PCI slot
  • Oxford OXuPCI954 chip drives four 16550 UART ports
  • Data rates up to 230 Kb/s per port
  • IRQ sharing plus 32-byte FIFO buffers cut conflicts
  • Selectable 5 V or 12 V power on each DB9

Four 9-pin RS232 ports added via PCI

The SIIG CyberSerial 4S 550 adds four 9-pin RS232 serial ports to a desktop computer through a 32-bit PCI slot. Two ports face the rear bracket and two are routed internally for front-panel or chassis connections. It targets users who still operate legacy serial equipment such as industrial controllers, barcode scanners or POS displays.

PCI bus limits throughput to 230 Kb/s per port

Each 16550 UART tops out at 230 Kb/s, and the shared 32-bit PCI bus cannot exceed that aggregate bandwidth under heavy multi-port load. The Oxford OXuPCI954 chip supports IRQ sharing to ease interrupt pressure, yet the legacy PCI interface remains the bottleneck for sustained high-speed transfers across all four ports simultaneously.

Low-profile bracket fits standard PCI

The card installs in any 3.3 V or 5 V PCI or PCI-X slot, 32-bit or 64-bit, and the reinforced bracket resists flex during cable insertion. Configuration is handled by the operating system; no jumpers set IRQs or port addresses. The only common issue is forgetting to enable the internal headers in BIOS or selecting the wrong voltage jumper for powered peripherals.

How it compares

Measured against everything we stock in PCIe Expansion Cards, at today’s prices. Recalculated every night.

Price $53.99
Pricier than about 72% of the 891 comparable items (median $30.99).

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Specifications

Product
Brand nameSIIG
Model nameJJ-P45012-S7
Product typePCI to Serial Port Card
Ports & slots
External connectors2 x Serial Ports
Internal ports2 x Serial Ports
Size & build
Shipping weight0.25 kg
Package size220 × 160 × 38 mm

Questions about this item

How do I pick between the two external and two internal serial ports on this card?

The card provides four 9-pin RS232 ports in total — two on the bracket for external cables and two via internal headers for front-panel or chassis connections — so you use whichever mix matches your device locations.

What does the 230Kb/s headline rate mean once the card is installed in a real machine?

Each of the four 16550 UART ports can transfer up to 230Kb/s, and the 32-byte FIFO buffers keep throughput high even when Windows is multitasking.

The card uses a 32-bit PCI slot — what does that cap in practice?

It fits 32-/64-bit, 3.3V/5V PCI and PCI-X slots, so the bus width and voltage are not limiting factors for the four serial ports.

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