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Monoprice 100447 100ft DB9 Serial Extension Cable — main product image
Monoprice

Monoprice 100447 100ft DB9 Serial Extension Cable

★★★★★4.5 (2 reviews)

Extend any RS-232 serial device run by 100 feet with a straight-wired DB9 male-to-female cable that preserves pin-for-pin continuity.

$24.95*
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*Price sourced from Amazon.com. Last updated:Jul 14, 2026.Price and availability are subject to change.

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Overview

The Monoprice 100447 is a 100-foot DB9 male-to-female straight-through serial extension cable designed to lengthen an existing RS-232 serial run without altering the signal path or pin mapping. The DB9 connector carries up to 9 signal lines in the RS-232 serial standard — two data lines (transmit and receive), a ground reference, and six hardware handshaking signals (RTS, CTS, DTR, DSR, DCD, RI). A straight-through extension preserves all nine connections pin-for-pin, meaning devices that rely on hardware flow control (RTS/CTS) or modem status lines (DSR/DTR/DCD) continue to function through the extension. The molded overmold construction at both connector ends provides factory-applied strain relief — a meaningful build quality detail for connections that are moved, coiled, and re-routed during installation and maintenance cycles.

This cable is a legacy infrastructure component serving the substantial installed base of RS-232-dependent equipment that remains in active use in industrial, manufacturing, and specialized commercial environments: label printers, barcode scanners, CNC controllers, point-of-sale terminals, scientific instruments, and network gear with out-of-band serial management ports. The 100-foot length is relevant when a serial host (a PC COM port or USB-to-serial adapter) and its peripheral are separated by the width of a manufacturing floor, a server room, or a distance that short patch cables cannot bridge. At baud rates of 9600 to 38400 — the most common rates for legacy equipment — 100 feet is within reliable operating range. At 115200 baud, signal quality should be verified in the specific installation environment. The beige jacket color reflects the cable's age-of-design rather than any functional compromise.

Key Features

High quality high value Serial (DB9) Straight Extension Cables

A reliable and economical solution for extending your pre-existing serial cables

High quality molded connectors

Beige color

Monoprice continually strives to improve its product line to bring our customers the best products available

Therefore changes may be made to listed specifications without prior notice

Item received may not match photo or specs shown

Specifications

Connector Type
DB9 Male to DB9 Female
Length
100 feet
Wiring
Straight-Through
Pins
9
Connector Construction
High-Quality Molded
Jacket Color
Beige
Interface Standard
RS-232 Serial (DB9)

Pros & Cons

👍 Pros

  • 100-foot length covers the distance between a serial host and peripheral in most commercial or industrial floor layouts without requiring a signal repeater
  • Straight-through wiring passes all 9 DB9 pins including hardware handshaking lines (RTS/CTS/DTR/DSR), preserving the full RS-232 signal set for devices that use flow control
  • Molded connector construction provides factory-quality strain relief at both ends, reducing the connector failure rate under repeated connect/disconnect cycles
  • DB9 M/F configuration is the correct connector pairing for extending an existing male-terminated cable to a female-terminated device port
  • Monoprice's consistent manufacturing tolerances on molded connectors ensure consistent mating force across the production run without over-tight or loose engagement

👎 Cons

  • 100 feet at baud rates above 38400 approaches the practical RS-232 signal integrity limit — installations requiring reliable 115200 baud over this length may need a lower-capacitance cable or active signal booster
  • Beige jacket color integrates poorly with modern gray and black infrastructure cabling — visible in clean cable management environments
  • Monoprice's specification disclaimer (item received may not match photo or specs) introduces uncertainty about connector pin-out verification without testing each cable on receipt
  • Molded construction prevents field repair — a damaged connector at either end requires complete cable replacement rather than a connector swap
  • No locking thumbscrews are specified — in vibration-prone industrial environments, the connectors may require additional retention hardware to prevent accidental disconnection

Frequently Asked Questions

This is a straight-through extension cable — pin 1 on the male connector maps to pin 1 on the female connector, and so on through all 9 pins. It is intended to extend an existing serial connection, not to create a direct device-to-device link. If you need to connect two DTE devices directly (two computers without a modem), you need a null modem cable, not this extension.
RS-232 does not have a strict maximum cable length specification — the standard defines signal voltage levels and slew rates, and the practical cable length limit depends on baud rate and cable capacitance. At common industrial and legacy serial rates (9600 baud, 19200 baud), 100 feet is within reliable operating range. At 115200 baud, 100 feet is near the practical limit and may exhibit occasional errors depending on cable quality and load.
Yes — molded connectors are overmolded at the factory and cannot be disassembled or repaired in the field. If a connector is damaged, the cable must be replaced. The trade-off is that molded construction provides better strain relief than field-terminated connectors, making the cable more durable under repeated plug/unplug cycles.
Yes — DB9 is the standard connector for RS-232 serial interfaces on both PC COM ports and the vast majority of industrial serial devices (PLCs, CNC controllers, barcode scanners, label printers, test instruments). The physical connector mates with any standard DB9 receptacle.
A straight-through extension cable passes all 9 DB9 pins, which includes the data lines (TX/RX), ground, and hardware handshaking signals (RTS, CTS, DTR, DSR, DCD, RI). Hardware flow control will function through this cable provided the original device configuration and the extension length are within the RS-232 voltage margin.

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