All terms

Material, explained

Duplex or simplex?

Do I need a duplex or a simplex fibre cord?

Duplex for an ordinary transceiver, which needs one fibre to transmit and one to receive. Simplex is for pigtails spliced into a termination box, for test leads, and for bidirectional optics that send and receive on one strand at two wavelengths. If the optic has two ports, it needs a duplex cord, and the keyed pair is what stops the two being crossed.

Both are defined by ISO/IEC 11801 patch cord construction.

Published by Data Systems, network material suppliers in Secunderabad, Hyderabad since 1984, which is forty years of experience with these parts. Last checked 2026-08-11. How we check this, and what we got wrong.

Side by side

DuplexSimplex
Fibres in the cordTwoOne
Connectors each endA keyed pairOne
Used withOrdinary two-port transceiversPigtails, test leads, bidirectional optics
Crossing transmit and receivePrevented by the keyingNot applicable
Specify it whenSwitch, server and equipment linksSplicing, testing, single-strand optics

Duplex, on the shelf

What Duplex is

Simplex, on the shelf

What Simplex is

Other choices we get asked about

Still not sure which the job needs? Describe the run and our team will tell you, and quote it.

Data Systems · +91 99595 55222 (call or WhatsApp) · admin@datasystems.co.in · Secunderabad (HQ) · Vijayawada · Visakhapatnam · Mon to Sat, 9:30 to 7

Some images on this site were created with AI and the item supplied may not look exactly as shown. The part code, not the picture, decides what ships.

Corrections and editorial policy · Privacy · Terms · Material, explained · Brands