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The difference between Simplex and Duplex Fiber Optic Cables

When talking about fiber optic patch cable, related products that firstly come to our mind are usually multimode and single mode fiber patch cable.Of course,there are still many other types. But as a beginners in this field might wonder what duplex and simplex fiber patch cables are. This text will introduce you about these cables. Before we come to simplex and duplex fiber patch cables, let’s firstly get familiar with the two words — simplex and duplex.

What Do Simplex and Duplex Mean?

According to the ITU-T definition, a simplex circuit is one where signals can flow in only one direction at a time. One end is the transmitter, while the other is the receiver and that is not reversible.

However, at other times, communications can flow in the reverse direction. That is half-duplex. Half-duplex system means a communication channel that operates in one direction at a time and may be reversible. A good analogy for half-duplex system will be two roads with a traffic controller at each end, in order to ensure smooth flow of traffic, the traffic controller only allows one direction at a time. But if one party transmits at the same time, a collision occurs, resulting in lost messages.

“Duplex” comes from “duo” that means “two”, and “plex” refers to “weave” or “fold”. A duplex system has two clearly defined paths with each path providing information in only one direction, that is A to B over one path, B to A over the other. Compared with half-duplex, a full-duplex system, or sometimes called double-duplex allows communication in both directions and allowing this to happen simultaneously. Just like the cellphone, both parties can speak and be heard at the same time.

Simplex Fiber Optic Cable:

Simplex Fiber Optic Cables will be used when a signal only needs to go in one direction. They are designed for production termination where consistency and uniformity are vital for fast and efficient operation.

Simplex Fiber Optic Cable consists of a single fiber,tight-buffered (coated with a 900 micron buffer over the primary buffer coating) with Kevlar (aramid fiber) strength members and jacketed for indoor use, and is used mostly for patch cord and backplane applications. Analog to digital data readouts, interstate highway sensor relays, and automated speed and boundary sensors (for sports applications) are all great uses of Simplex fiber optic cable. This form of fiber cable can be cheaper than Duplex cables, because less material is involved. Simplex Fiber Cable is a single fiber available in single mode, multimode, or polarization maintaining, and they can meet the strength and flexibility required for today’s fiber interconnect applications. We also supply Riser, Plenum rated constructions and LSZH jacket.

Duplex Fiber Optic Cable:

Duplex Fiber Optic Cables consist of two fibers joined by a thin connection between the two jackets. Either single mode or multimode,they are used in applications where data needs to be transferred bi-directionally. One fiber transmits data one direction; the other fiber transmits data in the opposite direction. Larger workstations, switches, servers, and major networking hardware tends to require duplex fiber optic cable.

Duplex fibers types:

Half-duplex: Data may only be transmitted in one direction at a time.

Full-duplex: Data is transferred in two directions simultaneously.

Other duplex infomation:A duplex communication system is a point-to-point system composed of two connected parties or devices that can communicate with one another in both directions, simultaneously. Now, Duplex systems are employed in many communications networks, either to allow for a communication “two-way street” between two connected parties or to provide a “reverse path” for the monitoring and remote adjustment of equipment in the field.

Some Tips To Choice Simplex And Duplex Fiber Cable

When purchasing a fiber optic cable, it is important to understand the different varieties of core characteristics that are available within the cable itself. Each of these different characteristics will have different effects on your ability to transmit information reliably, and these different characteristics also affect the cabling project. You must search the cost of fiber optic cable if you bought the cable. Now, let’s take a look at the most common fiber optic cables.

Simplex Fiber Cable

A simplex fiber cable consists of a single strand of glass of plastic fiber, and is used for applications that only require one-way data transfer. Simplex fiber is most often used where only a single transmit and receive line is required between devices or when a multiplex data signal is used (bi-directional communication over a single fiber). Simplex fiber is available in singlemode and multimode. For example, an interstate trucking scale that sends the weight of the truck to a monitoring station or an oil line monitor that sends data about oil flow to a central location.

Duplex Fiber Cable

A duplex fiber cable consists of two strand fibers of glass or plastic. Typically found in a “zipcord”(side-by-side) construction format, this cable is most often used for duplex communication between devices where a separate transmit and receive are required. Duplex fiber is available in singlemode and multimode. Use multimode duplex fiber optic cable or single mode duplex fiber for applications that require simultaneous, bi-directional data transfer. Workstations, fiber switches and servers, fiber modems, and similar hardware require duplex fiber cable.

Cable Design Criteria For The Pulling Strength,Water Protection,Fiber Code Ratings

Pulling Strength: Some cable is simply laid into cable trays or ditches. So pull strength is not too important. But other cable may be pulled through 2 km or more of conduit. Even with lots of cable lubricant, pulling tension can be high. Most cables get their strength from an agamid fiber, a unique polymer fiber that is very strong but does not stretch – so pulling on it will not stress the other components in the cable. The simplest simplex cable has a pull strength of 100-200 pounds, while outside plant cable may have a specification of over 800 pounds.

Water Protection: Outdoors, every cable must be protected from water or moisture. It starts with a moisture resistant jacket, usually PE (polyethylene), and a filling of water-blocking material. The usual way is to flood the cable with a water-blocking gel. It’s effective but messy – requiring a gel remover. A newer alternative is dry water blocking using a miracle powder – the stuff developed to absorb moisture in disposable diapers. Check with your cable supplier to see if they offer it.

Fire Code Ratings: Every cable installed indoors must meet fire codes. That means the jacket must be rated for fire resistance, with ratings for general use, riser (a vertical cable feeds flames more than horizontal) and plenum (for installation in air-handling areas. Most indoor cables use PVC (polyvinyl chloride) jacketing for fire retardance. In the United States, all premises cables must carry identification and flammability ratings per the NEC (National Electrical Code) paragraph 770.


After reading the above statements, do you have a brief understanding of simplex fiber patch cable and duplex fiber patch cable? When choosing one over the other, the key factor is that the equipment requires one-way or bi-directional data transfer. Fiber-Mart has large numbers of simplex and duplex fiber optic patch cables, such as single mode simplex fiber patch cable, LC to LC duplex single mode patch cable, 10 gigabit multimode duplex cables, LC ST duplex patch cord and so on. I believe you can find a suitable fiber optic patch cable for your devices in Fiber-Mart.please contact us:
Fiber-Mart department with core technical knowledge provides strong innovative capability. Fiber-Mart outstanding performance can meet the need of the customer.

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