Black Box CBCC332000 DB9F/DB9F Null-Modem Serial Cable 25 ft

Overview

The Black Box CBCC332000 is a 25-foot DB9 female-to-female null-modem cable built for direct serial connections between two DTE devices — think host-to-terminal, PC-to-embedded controller, or console-server-to-device links where no intermediate modem is in the signal path. The null-modem wiring swaps transmit and receive lines so both ends can communicate without a modem in between, which is exactly what you need when connecting serial peripherals directly to a control system or running a legacy RS-232 link across a rack or short cable run. At 25 feet, the CBCC332000 gives you enough reach to cross a server rack, span a short floor run, or drop from an overhead cable tray to rack-mounted equipment without a signal repeater. The stranded PVC jacket stays flexible through repeated re-routing and tight bend radii — a practical advantage in dense wiring environments where solid-core cables crack or fatigue over time. For integrators and IT teams maintaining serial connectivity infrastructure or legacy RS-232 equipment, this cable fits squarely into the working toolkit.

Key Features

• Null-Modem Wiring: TX/RX lines are crossed internally, so two DTE devices communicate directly without an intervening modem or converter — eliminates an extra device in legacy serial chains and simplifies troubleshooting.
• DB9 Female / DB9 Female Connectors: Both ends terminate in DB9F (9-pin D-sub female), matching the male DB9 ports found on most RS-232 serial interfaces, console server ports, and legacy industrial controllers — no gender changer needed in typical deployments.
• 25-Foot Length: Provides adequate reach for cross-rack or short-room serial runs while staying well within the RS-232 practical distance limits at typical baud rates. Long enough to avoid adapter stacking, short enough to keep signal integrity solid.
• Stranded PVC Construction: Stranded conductors resist fatigue and maintain flexibility when the cable is routed around corners or repositioned during equipment changes — a meaningful durability factor in dense data center or control room environments compared to solid-core alternatives.
• Black Jacket: The black PVC jacket blends into standard rack and cable management aesthetics and is easy to identify against lighter patch cables in mixed-cabling environments.
• RS-232 Compatible: Designed for standard RS-232 serial connections, making it interoperable with a wide range of serial devices including terminal servers, legacy PLCs, KVM switches, network appliances with console ports, and out-of-band management equipment.

Integration and Compatibility

The CBCC332000 is compatible with any RS-232 DTE device that exposes a male DB9 connector — including most console server ports, serial-enabled network switches, legacy industrial controllers, and out-of-band management appliances. Null-modem wiring makes it the correct choice any time you are linking two devices that would normally require a modem between them, such as a PC serial port and a programmable controller or a terminal server and a managed switch console port. If your application requires a DB9 male-to-female or straight-through pinout rather than null-modem, verify the wiring configuration before ordering — using a null-modem cable where a straight-through cable is required will result in no communication. For longer serial runs, RS-232 signal quality degrades with distance and baud rate; at standard baud rates (up to 115,200 bps), 25 feet is a comfortable operating length, but very long runs or high baud rates may benefit from an RS-232 to RS-422/485 converter rather than a longer RS-232 cable. This cable integrates naturally with data center infrastructure and control room serial management setups that rely on Black Box connectivity products.

Frequently Asked Questions

Q: What is the difference between a null-modem cable and a straight-through serial cable?

A: A null-modem cable crosses the transmit and receive lines between the two connectors, allowing two DTE devices (such as two computers or a PC and a controller) to communicate directly. A straight-through cable connects each pin to its matching pin on the other end, which is used when a modem is in the path. Use the CBCC332000 when connecting two serial devices directly without a modem.

Q: Will the CBCC332000 work with my console server's RS-232 port?

A: The CBCC332000 terminates in DB9 female connectors on both ends and uses null-modem wiring. Most console server serial ports expose male DB9 connectors, so the physical fit is typically correct. Verify that your specific console server requires null-modem pinout (rather than straight-through) before use, as wiring type affects whether communication is established.

Q: Is 25 feet long enough for a typical rack-to-rack serial run?

A: For most within-rack or adjacent-rack console and management connections, 25 feet is sufficient. RS-232 operates reliably at this distance at standard baud rates. For runs exceeding 50 feet or at very high baud rates, consider an RS-422/485 solution rather than a longer RS-232 cable.

Q: Does the CBCC332000 support hardware flow control (RTS/CTS)?

A: Standard null-modem cables typically include RTS/CTS line crossings to support hardware flow control. Refer to Black Box's product documentation for the exact pinout of the CBCC332000 to confirm flow control line wiring for your application.

Q: Can I use this cable for connecting two PCs for a direct serial file transfer?

A: Yes — null-modem cables are the classic solution for direct PC-to-PC serial connections used in legacy file transfer, terminal emulation, and direct serial communication scenarios. The CBCC332000's 25-foot length accommodates desktop-to-desktop or PC-to-rack connections in most room layouts.