Definition - What does Twinaxial Cable (Twinax) mean?
A twinaxial cable (twinax) is a type of cable similar to the common coaxial copper cable, but has two inner conductors instead of one. It has been primarily used by IBM for its IBM3x and AS/400 computer systems. The cable has recently seen wider use, especially for applications that require high-speed differential signaling in a short-ranged scenario, such as in local area networks.
Twinaxial cables were originally made for IBM computer hardware such as the IBM 5250, IBM printers and their midrange hosts and iSeries systems that use the IBM i5/OS. It was designed by IBM to be high speed (1 Mbit/s) and can have multiple addressable devices per connection; seven devices can be addressed starting from workstation address 0 through 6. The main disadvantage of it initially was the large connectors that usually needed screws to stay in place.
The twin conductors of the twinax cable do not carry individual signals, nor is one considered as data and the other ground. The cable works in a half-duplex mode, as both connectors are required to transmit data. For example, to deliver a 0, wire A has to be greater than wire B for the first half of the bit duration and then A needs to be less than B on the next half. To deliver a 1, the reverse is done. All of this happens in 250 ns.