Black Box EYN257T-0010-MF 10-ft RS-232 Shielded Null Modem Cable

Overview

The Black Box EYN257T-0010-MF is a 10-foot shielded RS-232 null modem cable with a DB9 male-to-female connector configuration and metal hood construction. Null modem cables are used to connect two DTE (Data Terminal Equipment) devices — serial port to serial port — without a modem in between, making this the correct pick for direct serial console connections, POS terminal configuration, legacy industrial controller setup, and serial device cross-connects in rack environments. If you are deploying or servicing equipment that requires a crossed RS-232 link at close range, EYN257T-0010-MF (often searched as EYN257T 0010 MF) covers the job in a compact 10-foot run.

Key Features

• Null Modem Wiring: Crosses the transmit and receive lines so two serial devices communicate directly — no intermediate modem or adapters required. This is the configuration you need when connecting a PC serial port to another PC, a terminal server, or a serial-interface device controller.
• DB9 Male/Female Termination: The DB9 male-to-female pairing is the most common RS-232 null modem connector combination, fitting standard 9-pin serial ports found on legacy PCs, industrial controllers, access control panels, and serial-to-IP converters without additional gender changers.
• Shielded Construction: The shielded cable jacket suppresses electromagnetic interference — relevant in rack environments with dense power wiring, near UPS units, or in industrial control rooms where EMI noise can corrupt low-voltage serial signals and cause dropped characters or parity errors.
• Metal Hood Connectors: Metal hood strain relief adds mechanical durability at the connector body, reducing the risk of cable fatigue at the termination point — a real-world concern on cables that get repeatedly connected and disconnected during commissioning or serviced periodically in tight rack spaces.
• RS-232 Protocol: Operates over the RS-232 standard, which is the dominant serial interface for console access, legacy automation equipment, and many serial-based access control and intercom system configuration ports. No drivers or power required — plug and go.
• 10-Foot Length: Sized for rack-adjacent connections — long enough to reach between adjacent rack units or a nearby workstation during configuration, short enough to avoid signal integrity problems inherent at longer RS-232 runs. RS-232 is spec'd to approximately 15 meters at standard baud rates; 10 feet keeps you well within margin.
• Black Color, Commercial-Grade Build: Fits cleanly into professional rack and AV installations without standing out visually, consistent with Black Box cable product standards for commercial environments.

Integration and Compatibility

The EYN257T-0010-MF is compatible with any device using a standard 9-pin RS-232 serial port. Common deployment pairings include serial console ports on managed switches, serial configuration interfaces on access control panels and DVRs, POS terminal direct connections, legacy industrial automation controllers, and KVM extender serial pass-through ports. Verify the device's DB9 gender and null modem requirement before ordering — if both devices have male DB9 ports, a standard null modem cable with two female ends is the correct choice instead.

Frequently Asked Questions

Q: What is a null modem cable and how does it differ from a standard RS-232 serial cable?

A: A null modem cable crosses the transmit and receive signal lines so two DTE devices (like two computers or a PC and a serial controller) can communicate directly without a modem. A standard RS-232 cable passes signals straight through and is used between a DTE and a DCE (modem). If you are connecting serial port to serial port, a null modem cable like the EYN257T-0010-MF is what you need.

Q: What connector types does the EYN257T-0010-MF use?

A: It uses a DB9 male connector on one end and a DB9 female connector on the other end — the standard 9-pin RS-232 configuration found on most serial port devices.

Q: Why does shielding matter on a short 10-foot RS-232 cable?

A: In environments with dense power wiring, UPS units, or other EMI sources — common in server rooms and industrial control panels — unshielded serial cables can pick up interference that causes data corruption or parity errors. The shielded construction on the EYN257T-0010-MF reduces that risk.

Q: Can I use this cable to connect a PC to a router or managed switch console port?

A: Many router and switch console ports use RJ-45 connectors rather than DB9, often requiring a separate RJ-45-to-DB9 adapter. Check your device's console port type first. If the device has a DB9 serial console port and requires null modem wiring, yes — this cable is appropriate.

Q: Is the EYN257T-0010-MF suitable for permanent installation or just temporary bench use?

A: The metal hood construction and shielded cable make it suitable for semi-permanent installations in rack environments, not just bench or temporary use. It is a commercial-grade serial cable built for repeated connection cycles.

James Everett

The EYN257T-0010-MF comes up regularly in rack commissioning and serial console work — it is the kind of cable that gets overlooked until you need it and do not have it. The shielded construction and metal hood are the two details that separate this from generic serial cables you would pick up at a retail store; in an EMI-dense rack environment, those details matter for reliable RS-232 data transfer.

Technical Highlights:

• Null Modem Crossing: Transmit/receive lines are crossed at the cable level — you do not need a null modem adapter inline, which removes one potential point of failure in a serial console chain.
• DB9 Male/Female Configuration: Covers the most common direct serial connection scenario without requiring gender changers; fits most 9-pin RS-232 ports on access control panels, legacy DVRs, and industrial controllers without modification.
• Shielded with Metal Hood: Shielding suppresses EMI pickup; metal hood reduces mechanical strain at the termination — both relevant for cables routed through busy rack environments rather than sitting on a bench.

Deployment Considerations:

• Confirm null modem wiring is actually required for your connection — if one device is DCE (a modem or serial server presenting a DCE interface), a straight-through cable is what you want, not a null modem.
• RS-232 signal integrity degrades past roughly 50 feet at higher baud rates; at 10 feet you are well within spec, but if you need a longer run, evaluate RS-422 or RS-485 alternatives rather than extending RS-232 beyond its practical range.

This cable is the right fit for serial console access to rack-mounted equipment during commissioning — managed switches, access control head-ends, serial-interface DVRs — where you need a reliable, interference-resistant connection in a dense rack without adapter stacking.