IT cabling: Quo vadis?

M12 connector X-coded – suitable for use in industry while also offering high performance

Standards have been in place for application-independent IT premises cabling since 1995. The terms “Cat. 5” and “RJ45” have become commonplace. These categories represent Transmission characteristics and backward compatibility. The higher the category, the more bandwidth available. The commonly used abbreviation “RJ45” stands for a mating face that has been accepted worldwide as the dominant data mating face in the workplace. The official Designation is EN 60603-7, behind which lies a family of Standards for connectors in categories 5 to 7 categories and the uniform mating face, hail from international Standard ISO/IEC 11801, “Customer Premises Cabling”, which has its German Counterpart in DIN EN 50173. “Competition” to IT cabling is in the air: Wireless and radio links are offering ever increasing bandwidth. Therefore the question: Cabling - Quo vadis? Where are things headed? The answer: cabling is progressing towards even higher data rates and increased capacities for remote power supply! Compared to wireless, cable-bound transmission offers unbeatable advantages. On the one hand, each end-user has exclusive access to the bandwidth. On the other, electrical power can be transmitted to the end devices in parallel to the transmission of Information.

RJ45 plug – as RJI10G, suitable for use in industry, by HARTING


Besides telephony, Ethernet represents another common data-transmission application that uses twisted pairs, and boasts data rates up to 10 Gbit/s. The relevant IEEE 802.3 committee is currently working on 40 Gbit/s. 40 Gbit/s transmission will still not be “the end of the line”. As part of a project sponsored by the Federal Republic of Germany, HARTING and LEONI have teamed with Reutlingen University on research into 100 Gbit/s over twisted pair cables. Higher data rates require greater transmission bandwidth and consequently higher Peak frequencies. For Cat. 7A this is 1 GHz, and is expected to be 1.6 GHz for Cat. 8. The new categories will be incorporated into the new edition of ISO/IEC 11801, which we expect in 2016/2017.

M12 plug – X-coded variant with eight contacts, for 10 Gig

Remote power supply

By way of example, the “competitor” referred to as wireless transmission is employed in WiFi applications. WiFi is attractive because it offers end devices flexibility and mobility. WiFi requires access points. These in turn require data interfaces and a power supply – both of which can be provided by IT cabling if it also supplies remote power in parallel with data transmission. At present, IEEE 802.3 offers components that can receive 300 mA of power per wire via remote supply. This is transferred either via unneeded pairs or by way of the so-called phantom circuit. IEEE  802.3bt and the working group ISO/IEC JTC 1 SC 25/WG 3 are currently working on boosting the capacity of remote power. The goal is to be able to supply an end device with 49W (!) of remote power via the data cable, with 500 mA per wire.

RJ45 connector with angled cable outlet

And finally, the question: One, two or four pairs?

The analog phone requires one pair to transmit the send and receive signal. This transmission occurs in so-called full-duplex mode, i.e. simultaneously in both directions. In digital transmission over symmetrical twisted pairs, the transmit and receive directions were initially transmitted separately via their own pair. This is e.g. the case with ISDN and 10 Mbit/s and 100 Mbit/s Ethernet. In these cases, two pairs are sufficient for transmission. Ethernet with Gbit/s transmission rates, i.e. 1000 BASE-T and 10 GBASE-T, employs parallel transmission over four pairs. Thus the cabling requires four pairs for the connection to an end device. Most recently, a new area of application requires a reduction in the number of pairs. Plans call for 1 Gbit/s transmission in automobiles over a single pair (!), in order to achieve space and weight savings.

In brief: 

  • Electrical power is to be transmitted to end devices in parallel with the transmission of data.
  • The relevant IEEE 802.3 committee is currently working on 40 Gbit/s.
  • Higher data rates require greater transmission bandwidths and therefore higher peak frequencies.
HARTING RJ Industrial® Ethernet Date Interfaces

Circular M12 connectors with X-coding