The 'One Cable Automation' (OCA) concept is based on connecting individual field devices, decentralized terminal boxes and even machine modules with just one cable. This combines communication via Ethercat and the power supply required for the connected components. Beckhoff implemented this in the first step for the 24 V field level via a standard Ethernet cable with the 24 V system and peripheral voltage (US and UP respectively). An M8 connector with a corresponding mating face was developed for this purpose, which reliably protects against mismating with standard Ethercat slaves by means of mechanical coding.

The ECP (pictured) and ENP series connectors are ideal for connecting stepper motors with controllers (B12), for asynchronous motors with frequency converters (B17) and for robot applications (B23/B36).

© Beckhoff Automation

For higher performance requirements for a single-cable solution, Beckhoff worked in parallel on two new connector families, which are now available. These combine Ethercat or Ethercat P with additional power cores in the cable - concealed and with a high IP67 degree of protection. All in all, the 'One Cable Automation' concept combines the following approaches:

• Ethercat P communication with integrated power supply - i.e. the single-cable solution with M8 connector and
• a single-cable solution with hybrid cable or based on the new ENP or ECP connectors. This approach combines either an Ethercat or Ethercat P communication element with additional power cores. In other words: Either 'Ethercat communication + power supply' or 'Ethercat communication + integrated 24 V supply + power supply' via one and the same hybrid cable.

Different distances can be bridged as required with the appropriate single-cable solution for devices and components with different power requirements. Another decisive factor here is the openness for mixed system concepts, i.e. for flexible switching between the two variants mentioned and also the conventional two-cable solution with separate power supply (Ethercat via M8/RJ45 connectors or Ethercat/Ethercat P via ENP/ECP connectors).

The new connector concept

With various performance classes for the components to be connected and the ECP and ENP connection variants, 'One Cable Automation' forms the basis for modular machine and system design.

© Beckhoff Automation

The ECP and ENP connector families mentioned above are specifically a combination of a communication and power element in various performance classes from 3 to 64 A in an extremely compact design. The difference between the two connector families:

• ECP (Ethercat P + Power): This connector series combines a compact, trapezoidal Ethercat P element - with the same pin assignment as the Ethercat P-coded M8 connector - with additional power pins. In this way, the 24 V supply integrated in Ethercat P is supplemented by an additional power transmission. This makes it possible to dispense with the four wires normally required for 2 × 24 V and thus use a thinner, more cost-effective cable or provide additional voltages.
• ENP (Ethercat/Ethernet + Power): These connectors connect a central communication element, which is also trapezoidal, with additional power pins in the same way. In this case, the trapezoidal element, which is inverted to prevent mismating, is used for data transmission via Ethercat, standard Ethernet or other Ethernet-based communication protocols.

The respective sizes from B12 to B36 are available with different numbers of power pins (2 to 6-pin) to adapt to the different network types and current consumption of connected consumers required in practice. The continuous 360° shielding of the central trapezoidal element enables the usual Ethercat performance. In addition, the compact design leaves sufficient space for the power pins, thus ensuring their high current-carrying capacity and dielectric strength. Further application advantages are provided by the easy-to-use bayonet lock and the wide range of flanges in a wide variety of housing variants for rear panel, front panel and square mounting. There are also field-assembled variants that can be installed in a time-saving manner.

The range of applications

New power distributions provide Ethercat communication via the B17-ENP connector - for higher power or further distances - in conjunction with two 24 V voltages and the protective earth conductor.

© Beckhoff Automation

Together with the Ethercat P-coded M8 connector, the completely newly developed ECP and ENP connector families now cover all applications from 24 V(DC) at I/O level to drive technology with 480 V(AC) and a maximum of 64 A. Depending on requirements, Ethercat, Ethercat P or their mixed use can be provided. Ethercat P, which is limited to 3 A each for US and UP via M8 or ECP connectors, is predestined for the typical mechanical engineering sector with small and medium-sized systems. For more complex systems - i.e. longer distances - the ENP version is more suitable. The same applies to applications without Ethercat P, for example if a 24 V power supply unit is already present at the end point or very powerful 24 V consumers are to be supplied.

Based on the concept described above, Beckhoff has introduced two new Infrastructure Box modules: a 1-channel and a 4-channel module. These are power distributors that provide 24 V voltage and the protective conductor twice via B17-ENP connectors as well as Ethercat communication in the trapezoidal element. The cross-section of the power cores is around five times larger than that of the Ethercat P element, allowing greater distances to be bridged and significantly higher currents to be transmitted - up to 20 A at ambient temperature - compared to an Ethercat P connection. In the future, complete 'socket strips' with data and power supply are conceivable, which can then be used to connect individual machine parts or individual devices in the field with just one cable.

Finally, when planning a specific machine or system, users have the option of configuring the individual Ethercat P consumers and cable lengths with Twincat tool support. A new, very compact Ethercat P box measuring 30 mm × 86 mm × 26.5 mm also provides important additional information for the best possible and cost-saving design of the network. This records the voltages US and UP as well as the currents IS and IP in the system and forwards the information to the controller. If the system knows the data of all consumers, the power consumption of the individual devices can also be taken into account over time. If, for example, two actuators never switch at the same time from a logical point of view, this can be taken into account when designing the maximum current. This results in further savings potential with regard to the required power feeds and power supply units.

Authors:
Dirk Bechtel is Senior Product Manager Fieldbus Systems at Beckhoff Automation;
Thomas Rettig is Senior Product Manager Ethercat Technology at Beckhoff Automation.