Is Single Pair Ethernet Cable the Future?

It’s been more than two decades that the cable authorities have standardized data and voice applications as 4 pair, ScTP or Sc/FTP, balanced UTP, Sc/FTP cables that support up to 40 Gigabits per second on 30 meters for CAT8. The major reason behind this requirement is the demand for high bandwidth that meet with the customer requirements.

The rising interest in Internet of Things and Smart Systems have also changed the scope of future cabling systems. For example, HVAC, lighting sensors and other smart systems require less amount of bandwidth as compared to data applications. A sensor, when polled by a controller or an external event, doesn’t transmit more than some bytes of data.

Due to the high demand of bandwidth for ethernet cables, IEEE has started developing a new protocol for ethernet which will operate more than a single pair of STP/UTP cable. Now, although the intent was to enhance the bandwidth available through four cables in industrial installations, 100Base-T1 and 1000Base-T1 are quite popular too.

Advent of a New Option

During the month of March, this year (2018), IEEE802.3cg Single Pair ethernet task force authorities gathered near Chicago with the goal of defining electrical requirements for 10Base-T1 – the potential name. According to the task force, the approval for the standard might happen in June 2019.

One of the biggest changes in the installation requirements is the total number of connectors that are permissible in a link. Industries are a target market for 100Base-T1 and cables and one can penetrate cable pathways as well as sealed enclosures in the installation when it comes to accessing the protected equipment.

For electronics that are small, cost effective and consume less power, 10Base-T1 offers several advantages as compared to existing single-pair ethernet options. It will be the preferred choice in future when it comes to cabling the sensors, low data consumption devices and sensors. Also, in future, as networks become omnipresent, the applications of new systems will also go beyond cabling. The vehicles, for example, will become smart through future applications.

Considerations for Cables

Cables that support 10Base-T1 applications are compact and small or rugged and large. When it comes to commercial installations, the cable designers have to deal with thousands of sensors and devices. And with numerous cables to manage, it is better to have smaller routes.

You might find 24 AWG conductors covered with thin jackets that lessen the cross-sectional size of the cable. At the frequency of 200MHz there is no possibility of alien crosstalk and hence it is possible to bundle the cables without worrying about signal interference. Cat6A UTP has thin jackets that increase the space between cable conductors to lessen the effects of alien crosstalk at 500MHz.

With industrial installations in which you can use 1000-meter links, the contemplations are different. The long links go through insertion loss which you can solve in two ways. One, the 1000m link topology of 10Base-T1 has to use a PHY (a kind of ethernet transceiver) which operates at 20Mhz as compared to 200MHz for 15m PHY. Attenuation is proportional to frequency and length. And hence, long cables increase the attenuation and if you limit the frequency to 20Mhz, it will lessen it. Cabling conductors for 1,000m link segments could have up to 18 AWG diameter, lessening the attenuation further. The ISO/IEC and ANSI/TIA standard groups have also started defining connectors and cables for 802.3cg/10Base-T1.

Development of Single Pair Cabling Standards

The ISO/IEC and ANSI/TIA structured cabling standard groups have developed specifications for single pair cabling for industrial and commercial installations with a wide range of distances and data rates. TIA is working on a new single pair cabling standard which will be known as TIA 568.5. This standard will define single pair cabling to support 10 Mb per second to 100 meters, 100 Mb per second to 15 meters and 1 Gb per second to 15 and 40 meters. This cable also supports an alternative of PoE known as PoDL – pronounced as poodle which has the potential to give up to 50 watts of power over a single 24 AWG pair.

The TIA will also make amendments for the TIA 1005 industrial cabling standard which define the cabling that supports 10 Mb/s to 1000 meters. For counteracting the signal loss on long cables, the conductor size goes up to 18 AWG for this application.

ISO is also working on making some changes. ISO 11801-9906 Ed. 1 and 11801-6 Ed.1/Amd.1 standard will cover the commercial cabling specifications for 10/100/1,000 Mb/s single-pair cabling, and 11801-3 Ed.1/Amd.1 will take care of cabling for industrial applications.

Is This an End for RJ45 Cables?

As you read before, ISO and TIA are already in the process of selecting a new single pair connector which they can use to support these applications. This with the intent to have a connector which is 1 half to 1 third the frontal area size of RJ45 cable and supports 1 amp of current – shielded/unshielded and conductor sizes from 18 to 26 WG.

The future of field-testing specifications of single pair cabling is quite bleak. All that we know at this point in time is that the types of tests that the authorities might conduct and what would be the established standards for it to pass or fail. Although the applications might allow the usage of UTP cable, wise integrators may go for STP for keeping the alien crosstalk at bay.