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IEEE-488 GPIB Tutorial

What are GPIB cables?
GPIB cables consist of 24 twisted pairs of copper wire and utilize a Centronics 24 style male/female connector.

How are GPIB cables used?
GPIB cables are used in a bus or star architecture where the connectors “piggy back” each other and then connect primarily test and measurement equipment to PCs and other devices.

Where are GPIB cables used?
GPIB cables are typically used in test and measurement applications and are also used in DAQ (data acquisition) applications.

IEEE-488 GPIB Cabling Terms

Adapter: A device used to interconnect two different connector types.
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 onto a connector. The device protects the conductors and can be assembled or injection molded.
Bus: Also called a "Daisy Chain". A network topology where each node is connected to one another in line. A major disadvantage is that when there is a break in the bus the entire network goes down.
Cable: A set of insulated wires or conductors within an extruded jacket. Many types of cable utilize shielding around the wires and under the cable jacket.
Cable Assembly: A piece of 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. Contacts can be male (pins) or female (sockets).
Coupler: A device used to connect two similar connector types.
Crosstalk: Is said to be the coupling of electromagnetic fields from conductors into adjacent conductors. Crosstalk is controlled by twisting conductors into a pair or separating/shielding conductors.
Electromagnetic Interference (EMI): Unwanted electrical or electromagnetic energy that causes unwanted responses in electronic equipment.
GPIB: General Purpose Interface Bus. Common name for IEEE-488.
HPIB: Hewlett Packard Interface Bus. Common name for IEEE-488.
IEEE-488: Institute of Electrical and Electronics Engineers interface standard number 488.
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.
Insulation Displacement Contact: A means of terminating wires without the need of stripping down to the bare wire.
Jack: The female receptacle - usually found on equipment.
Plug: Popular term for a male gender connector of varied types.
Shielding: A conductive foil or braid that covers insulated wires in a cable. The shield provides electrical grounding and protection from external electromagnetic interference (EMI). Shielding is also used to control internal electromagnetic radiation.
Strain Relief: A method of protecting the wire to contact point from flexing or pulling.
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: Conductive material (typically copper) that has been drawn down to a specific size and coated with an insulating material. A "bare wire" utilizes no insulator coating.

In-Line / Linear Configuration
In-Line / Linear Configuration


IEEE-488 Connector Specifications
The IEEE-488 GPIB connector utilizes 24 contacts in a parallel configuration.
IEEE-488 Connector Specifications

Physical / Star Configuration
Physical / Star Configuration

IEEE-488 Construction
  • 24 conductors with twisted pairs
  • Braid Shield with a minimum 85% coverage
  • Centronics style 24 position male to female piggy back connectors allowing for easy daisy chaining
  • Metric mating hardware, M3.5 x 0.6
IEEE-488 Cable Construction

L-com IEEE-488 Cable Assembly Options

L-com offers three different cable options to best satisfy customer needs and maximize value:

Backshell DetailPVC molded backshell over internal steel shell enclosureDie cast aluminum, nickel plated backshellDie cast aluminum, nickel plated backshell
Connector DetailStamped steel, nickel plated connectorsDie cast alloy, nickel plated connectorsDie cast alloy, nickel plated connectors
Contact Plating30 microinch gold plated contacts30 microinch gold plated contacts30 microinch gold plated contacts
Cable ShieldingOne braid and one foil/mylar overall shieldOne braid and one foil/mylar overall shield plus one inner foil/mylar shieldOne braid and one foil/mylar overall shield plus one inner braid and one inner foil/mylar shield

Molded IEEE-488 Cable Makeup

CMB / CIM / CIMB / CMC / CMD Series

L-com is the Originator
L-com was the first to introduce molded, in-line, male only GPIB cables. Acceptance was immediate and soon users demanded upgraded models with metal connector shells and better cable shielding gradations. Now the female version has been added to complete the series.

We complied with your wishes and we’re proud to offer the latest premium and deluxe versions of single ended cables which we list as standard items.

We urge you to try this wiring concept and to discover the many real advantages.

Molded Cable Makeup

Deluxe IEEE-488 Cable Makeup

CIF Series

The Industry Standard
Hewlett Packard set the criteria in the design of optimum IEEE-488 GPIB cables having three shields, twisted pairs and metal shells, offering maximum performance.

L-com agreed with this need and developed a comparable cable type that we call the CIF Series. This family of IEEE-488 GPIB cables is directly interchangeable with HP, AMP and Amphenol.The Deluxe Series is by far your best buy compared to any of the GPIB cables on the market today.

Deluxe Cable Makeup

Premium IEEE-488 Cable Makeup

CIB / CBC / CBD / CBX Series

L-com offers the Most Value
A reminder that the difference in cost between good quality wiring components and the IEEE-488 cables offered by discounters is very little indeed. When you consider the total value of the equipment that will be tied into a system, the cost of cables, adapters and accessories becomes only a small part of the total investment.

In many applications, it is wise to use the premier cables on the market, L-com’s Premium Series. Our cables and accessories are of the highest quality and our prices are realistic. We feel confident that if you compare Quality, Variety, Service and Price you will find that L-com definitely comes out on top on all counts.

Premium Cable Makeup


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