In today’s industrial automation systems, Ethernet plays a major part. The network relies on data being passed through the system at high rates to underpin the performance of the network.

The digital performance of a network is subject to the active devices within the network, such as switches and controllers. However, it is the passive devices such as cable and connectors which can ultimately determine a network’s performance.

The frequency performance of a component dictates its performance. Let us take Cat 5 cable as an example. Cat 5 cable is specified for operating frequencies up to 100MHz. However, the cable is suitable for 100MBIT applications using two pairs and gigabit applications (1,000MBIT) using a 4 pair cable in association with the correct connector.

It is easy to confuse MHz performance with the MEGABIT.

Class                                                       Frequency                Data Rate Capability
Range                     100Mbit                   1GBIT

Cat 5/5e                     100MHz                   2 Pair                       4 Pair

Cat 6                         350MHz                   ✔                             ✔

Cat 6A                       500MHz                   ✔                             ✔

Clearly, cables of a higher category (Class) meet all the transmission characteristics of the lower classes, they, therefore, provide additional performance margin in a given application.

Conductor Size  Stranded Ethernet cable does not have the same performance characteristics as a solid conductor. This must be remembered when the distance is a factor. Ethernet conductors are typically 26AWG and 24AWG, and it is always best to use the largest size when requiring high data rates over a long distance. The Profinet standard saw 22AWG cables being introduced, with this wire size there is significant transmission performance advantage over 26AWG and 24AWG, full 100m segment length can be achieved with stranded or solid cable types. Three types have been defined within the Profinet standard (see table below). Care must be taken to select the correct RJ45 connector when using 22AWG cables as many are not compatible with the increased wire size and the larger o/d of Profinet cables.

Power Over Ethernet  Spare conductors in an Ethernet cable can be used to provide power to Ethernet devices. Clearly, wire size is important in the calculation of voltage drop in POE applications and is important to bear in mind in cable selection.

Cable Selection  The industrial environment requires suitable cables which have far more robust constructions than those used in office environments. Materials such as PUR are often used to provide mineral oil resistance, high abrasion resistance and are halogen-free.

Ethernet cables are available with solid conductors which are only suitable for static applications.

Stranded conductors typically 7 strands for flexible use.  Highly stranded, typically 19 strands for continuous movement e.g drag chain applications.

For help with selecting the right Ethernet Cable for your machine environment, in conjunction with LUTZE UK, we have created an easy-to-follow selection guide.  Please click here…

And for further detailed information about Ethernet Connectivity, please download Lutze’s Ethernet Connectivity guide