Introduction
Embedded numerical control systems are a type of software system designed to provide control over electromechanical operations in a machine. In an advanced system, they are designed to increase the efficiency and accuracy of the machine through automation and improved monitoring of critical operations. A critical component in such a system is the embedded numerical control (NC) communication functionality, or communications protocol, which allows for communication between the embedded hardware and the physical machine. This paper aims to examine the various aspects of communication in embedded numerical control systems.
Communication Protocols for Embedded Numerical Control Systems
The most common communication protocol used in embedded numerical control systems is the Ethernet/IP protocol, which was developed by the Automation Industry Association (AIA) and is specifically designed for industrial networks. This protocol defines the communication structure, addressing, port specifications, and security features, making it an ideal choice for embedded applications. Additionally, Ethernet/IP can be easily extended to support additional communication protocols such as CANbus and Profibus.
Other communications protocols used in embedded numerical control systems include the PROFINET protocol and the SERCOS protocol. PROFINET is a real-time communications protocol developed by Siemens specifically for industrial automation. It is designed to enable rapid and reliable data exchange in networks of automation components, such as sensors and actuators. By using standard Ethernet technology, PROFINET substantially reduces costs compared to other protocols and can be easily integrated into existing systems.
The SERCOS protocol is another real-time protocol used in embedded numerical control systems. It is an open-loop communication interface built on top of Ethernet, allowing for fast and reliable data communication between the controller and the rest of the system. SERCOS provides a number of features including deterministic frame assignment, resource sharing, and broad coverage of communication protocols.
Data Link Layer Protocol
The data link layer is responsible for the synchronization of data and for ensuring the integrity of transmitted data. In an embedded numerical control system, the data link layer protocol is responsible for handshaking between the server and the peripheral, regulating communication between different protocol layers, and providing error detection and correction functionality. The most common data link layer protocols used in embedded numerical control systems are HDLC, SAE J1939, and CAN.
HDLC (high-level data link control) is a bit-level protocol that provides services for bidirectional data exchange between nodes connected by a link. Is a reliable point-to-point protocol for the transfer of frames containing data and control information between devices on a communication network.
SAE J1939 is a communication protocol used in heavy-duty and commercial vehicles. It is designed to provide more reliable communication between different control systems in these vehicles.
CAN (Controller Area Network) is an industrial bus protocol used in embedded systems. It is designed to support distributed real-time control and data exchange between nodes connected to a single communications link. It is often used in cars, buses, and trucks to exchange data within the entire vehicle.
Communication Channels
In order to enable the exchange of information between the embedded numerical control system and the machine, dedicated communication channels must be used. Communication channels can range from simple point-to-point connections to complex networked solutions.
Serial communication is the most common point-to-point channel used in embedded systems. This type of channel uses a single line of communications to transfer data between the controller and the peripheral. The most popular serial channels used in embedded numerical control systems include RS232, RS485, and TTL.
Networked solutions can be used to create more complex communication paths. Network solutions are often used in larger systems to enable the exchange of data between different controllers and peripherals. Networked solutions can use a variety of different protocols, such as Ethernet and Wi-Fi, and are often used to communicate between multiple machines or different systems.
Conclusion
Ensuring effective and reliable communication between the embedded numerical control system and the physical machine is a critical component in any automated system. Numerous communication protocols and channels exist to support the exchange of data between the controller and the machine, with the most common being Ethernet/IP, PROFINET, SERCOS, and the various data link layer protocols. Additionally, different types of communication channels, such as serial channels and network solutions, can be used to create more complex communication paths between different systems. Ultimately, choosing the right combination of communication protocols and channels will ensure the successful operation of embedded numerical control systems.
