D-Subminiature (Data Cabling) Tutorial

What is D-Subminiature?
D-Subminiature products are connection products utilizing various D-Subminiature style interface types to transmit data signals.

How is D-Subminiature used?
D-Subminiature products are used to connect a data generating device such as a CPU (Central Processing Unit) to a data producing device such as a printer.

Where is D-Subminiature used?
D-Subminiature products are used in numerous data transmission applications found in office, industrial, home or testing environments.

Data Cabling Terms

American Wire Gauge (AWG): A U.S. standard set of non-ferrous wire conductor sizes. Typical data wiring is AWG number 24, 26 or 28. The higher the gauge number, the smaller the diameter and the thinner the wire.
Backshell (Hood): A mechanical backing that is sometimes put on a connector. It protects the conductors and can be assembled or injection molded. Commonly used with D-Sub connectors.
Cable: Set of insulated wires or conductors within an extruded jacket. Many cable types use shielding around the wires and under the cable jacket.
Cable Assembly: A cable that has been terminated with one or more connectors.
Conductor: A metal path, usually copper, that passes electricity. When discussing data cabling, "wire" and "conductor" are synonymous.
Connector: Electromechanical coupling device that provides an electrical interface that can be mated and unmated.
Contact: The specific points of contact within a connector. May be male (pins) or female (sockets).
Contact Resistance: Resistance is basically the opposition to electron flow in an electrical circuit and connector. Manufacturers strive to attain the lowest amount of resistance possible for each contact. Contact resistance is the cumulative resistance value for mated contacts.
Crimping: A means of securing an electrical contact to a wire using tools that compress the metal contact around the wire.
Crosstalk: When unwanted electromagnetic fields from conductors are transferred into adjacent conductors. Crosstalk is controlled by separating or shielding conductors or twisting into a pair.
D-Subminiature: A common connector type that utilizes multiple pins and a D shaped housing.
Electromagnetic Interference (EMI): Unwanted electrical or electromagnetic energy that causes unwanted responses in electronic equipment.
Extrusion: The mechanical process of coating a wire or group of wires with insulating material.
Ground: Any zero-voltage point. Earth is considered a zero voltage grounding point.
Ground Wire (Drain Wire): Extra conductor, usually a bare wire, added to a cable for connection of the grounding path.
Injection Molding: The process used to inject molten polymer into a mold. Connector backshells are often injection molded.
Insulation: A material with very high resistivity used to protect conductors. Insulation is usually extruded over the wire or conductor after the drawing process.
Shielding: A conductive foil or braid that covers insulated wires in a cable. It provides electrical grounding and protection from external electromagnetic interference (EMI). Shielding is also used to control internal electromagnetic radiation.
Soldering: A means of securing an electrical contact to a wire by heating an alloy, usually consisting of tin and lead, also known as "solder".
Solid Wire (or Conductor): One strand of wire. Usually less flexible, lower in cost and lower in resistance than stranded wire of the same AWG. Solid wire is typically used in permanent installations where flexing does not occur.
Strain Relief: A method of protecting the wire to contact point from flexing or pulling.
Stranded Wire (or Conductor): Multiple small AWG strands of wire that are put together to make a flexible wire with similar electrical properties as a similar solid wire. Stranded wires are usually used in data cabling.
Twisted Pair: Two insulated conductors twisted at a fixed rate of twists per unit of length, typically used in balanced circuits where nominal impedance and crosstalk are critical characteristics.
Wire: A conductive material, usually copper, that has been drawn down to a specific size (see wire basics above) and is then coated with an insulating material. A "bare wire" utilizes no insulator coating.
Wire Drawing: The mechanical process of making conductors smaller by forcing through dies.

What is the difference between assembled and molded cable assemblies?

The difference between an assembled and molded cable assembly is in the construction of the backshell. An assembled backshell can be plastic (not shielded) or metal (shielded) and can be disassembled by removing hardware. On a molded cable assembly, the backshell is typically molded PVC that cannot be disassembled.

Selecting the right D-Sub Cable Assembly for your application

L-com takes pride in having the largest variety of D-Sub cables in the industry. The following selection guide is intended to assist you in selecting the right cable for your particular need.

Cable Series	Available Sizes	Available Connector Combinations	Color	Cable Shielding	Wire AWG	Distinguishing Characteristics	Photo
CSM	DB9, DB15, DB25, DB37	Male-Male, Male-Female	Gray	Foil/Mylar	26	Least expensive option Uses smaller, slotted screws instead of thumbscrews
CSMN	DB9, DB15, DB25, DB37, DB50	Male-Male, Male-Female	Light Gray	Foil/Mylar *	26 *	Most similar to industry standard cables
CSMNB	DB9, DB15, DB25	Male-Male, Male-Female	Black	Foil/Mylar	26	Black color for color matching black computer peripherals
CS2N	DB9, HDB15, DB25, DB37, DB15	Male-Male, Male-Female	Light Gray	Foil/Mylar + Braid	26	Extra cable shielding and steel internal enclosure provides maximum protection from EMI/RFI corruption
CRMN	DB9, DB15, DB25, DB37	Male-Male, Male-Female, Female-Female	Light Gray	Foil/Mylar	26	Reversible hardware feature allows cables to be directly panel mounted without the use of an adapter or any other component
CSMUZ	DB9, DB25	Male-Male, Male-Female	Black	Foil/Mylar + Braid	24	Low Smoke Zero Halogen (LSZH) jacket and backshell material significantly reduce the amount of toxic and corrosive gases emitted during combustion. Extra cable shielding and steel internal enclosure provides maximum protection from EMI/RFI corruption
CSNULL	DB9, DB25, DB25-DB9	Male-Female, Female-Female	Light Gray	Foil/Mylar	26	Data lines wired specifically to allow devices to communicate without the use of modems or other peripherals
CMZ	DB25 Male-DB9 Female	Male-Female	Light Gray	Foil/Mylar	26	Wired specifically to connect an external modem (DB25) to a PC serial port (DB9)
CHD	HDB15, HDB26, HDB44, HDB62, HDB78	Male-Male, Male-Female	Light Gray**	See below**	See below**	High density D-sub connectors utilize more contacts than standard D-sub connectors even though they use the same size connector shells

* Exception - CSMN50 is double shielded (foil/mylar + braid) with 28 AWG conductors
** CHD15 & CHD26 are foil/mylar shielded with 26 AWG conductors

CHD44 is double shielded (foil/mylar + braid) with 24 AWG conductors
CHD62 & CHD78 are double shielded (foil/mylar + braid) with 28 AWG conductors

What is the difference between standard and High-Density D-Sub Configurations?

The industry uses 5 different shell sizes; each shell size can have 2 different configurations of pins. Standard configurations are listed on top and High-Density are listed below.