For outsiders, the existence of Industrial Ethernet presents many confusing and isolated issues. Even experts are sometimes overwhelmed by the various competing systems emerging. Although manufacturers provide a great deal of information describing their technical specifications and specific functions, and try to offer easy-to-understand explanations, users will still find that they cannot obtain comprehensive information to support their investment in this area.
We will dissect and analyze the five major industrial Ethernet networks (EtherCAT, EtherNet/IP, ProfiNet, Modbus-TCP, and Powerlink) one by one.
EtherCAT
EtherCAT (Ethernet Control Automation Technology) is an open-architecture fieldbus system based on Ethernet. The "CAT" in EtherCAT is an abbreviation for Control Automation Technology. It was originally developed by Beckhoff Automation GmbH in Germany. EtherCAT sets a new standard for real-time performance and topology flexibility, while also meeting or reducing the cost of using fieldbuses. Features of EtherCAT also include high-precision device synchronization, optional cable redundancy, and a functional safety protocol (SIL3).
Ethernet/IP
Ethernet/IP is an industrial application layer protocol for industrial automation applications. Built on top of the standard UDP/IP and TCP/IP protocols, it utilizes fixed Ethernet hardware and software to define an application layer protocol for configuring, accessing, and controlling industrial automation equipment. Developed by Siemon.
PROFINET
PROFINET, launched by PROFIBUS International (PI), is a next-generation automation bus standard based on industrial Ethernet technology. As a strategic technological innovation, PROFINET provides a complete network solution for the field of automation communication, encompassing current hot topics in automation such as real-time Ethernet, motion control, distributed automation, fail-safety, and network security. Furthermore, as a cross-vendor technology, it is fully compatible with industrial Ethernet and existing fieldbus technologies (such as PROFIBUS), protecting existing investments.
PROFINET is a complete solution for various needs, with functions including eight main modules: real-time communication, distributed field devices, motion control, distributed automation , network installation, IT standards and information security, fault tolerance, and process automation.
MODBUS/TCP
MODBUS/TCP is a simple, vendor-neutral derivative of the MODBUS family of communication protocols for managing and controlling automated equipment. It obviously covers the uses of MODBUS messages in both "Intranet" and "Internet" environments that use the TCP/IP protocol. The most common use of the protocol is for services such as PLCs, I/O modules, and gateways connecting other simple domain buses or I/O modules.
The MODBUS/TCP protocol was released as a (de facto) automation standard. Since MODBUS is already widely known, this specification includes only a limited amount of information not found elsewhere. However, this specification aims to clarify which functions in MODBUS are valuable for interoperability with common automation equipment and which parts are "redundant" in MODBUS as a programmable protocol that can be interchanged with PLCs.
It distinguishes between general-purpose and optional messages by using a "consistency level" for the accompanying message types, especially those applicable to special devices such as PLCs.
POWERLINK = CANopen + Ethernet
Given the booming development of Ethernet and the extensive application of CANopen in the field of automation , EthernetPOWERLINK combines the advantages and disadvantages of these two technologies. It has the high speed and open interface of Ethernet, as well as the well-defined SDO and PDO data in industrial fields of CANopen. In a sense, POWERLINK is CANopen on Ethernet. The physical layer and data link layer use Ethernet media, while the application layer retains the original structure of the SDO and PDO object dictionary.
It is worth noting that POWERLINK has an open and independent standard technology that is applicable to any Ethernet hardware product, supports any topology type, has a cycle time of only 100 microseconds, and network jitter of less than 1 microsecond, fully meeting the high standards of real-time performance and determinism.
