Just when it appears that Ethernet will emerge from the pack of fieldbus networks, several different industrial Ethernet protocols and technologies emerge. Couple that with several device-level industrial networks, called fieldbuses, and you have a recipe for the reenactment of the Tower of Babel. If the vision of the next stage of automation evolution—that of distributed information and control—is to come to fruition, then perhaps what will be necessary will be a network “Babel Fish.”
As an answer to the many-protocol world of industrial networking, Hilscher GmbH, headquartered in Hattersheim, Germany, has developed and produced the “netX” network-on-a-chip. This small network controller contains an ARM microprocessor, which uses reduced instruction set computing, or RISC, technology developed by U.K.-based ARM Holdings plc, along with memory, multiple Ethernet interfaces and up to two fieldbus interfaces. It is said to be priced aggressively enough to encourage intelligent device manufacturers to include it in their products.
One-chip solution
This solves a major problem for these device manufacturers—the expense of developing, manufacturing and warehousing multiple devices that differ from each other only by the embedded network chip. Not only can one chip do the job, but the physical interface remains the same no matter which networking protocol is used, further reducing internal design and manufacturing cost, and complexity. Target devices for this controller are small and mid-size programmable controllers, small human-machine interfaces, input/output blocks, motor controllers, drives, weigh scales, bar code readers and more.
Not only does the chip support standard commercial Ethernet, it also supports the real-time Ethernet systems EtherCat, EtherNet/IP, Ethernet PowerLink, ProfiNet and Sercos III. It also supports a number of fieldbuses including AS-interface, CANopen, DeviceNet, Interbus and Profibus. The controller allows up to four programmable communications channels at a time, which can be configured by the development software. Developers could even add a proprietary protocol to let it interface with other networks. In addition, one channel has an analog-to-digital converter and encoder logic in order to run drive applications.
Core processor
The ARM microprocessor is a widely used core that can run Linux, Microsoft Windows CE and any of the real time operating systems.
Automation users should see a cost reduction for network-enabled devices from suppliers who design in this chip. Presently, these manufacturers must have multiple designs to provide solutions for the multiple technologies. With netX, a product vendor can make a single design that supports all the major technologies, and by changing a few minor parts along with the connector, offer any of the major fieldbus or Ethernet-based technologies in the market today. This increases production volumes, increases the number of available network offerings and reduces product costs. Further, by providing the network interfaces with the chip, companies can reallocate engineering resources from network stack development and maintenance to product features and functions.
The netX is a highly integrated network controller with a new system architecture optimized for communication and maximum data throughput. Based on the 32-bit ARM 926EJ-S central processing unit (CPU) at 200 MegaHertz, it possesses a memory management unit, caches, digital signal processor (DSP) and Java extensions. The internal memory of 144 Kilobyte random access memory (RAM) and 32Kbyte read only memory (ROM) that contains Bootloader and a real-time kernel is sufficient for smaller applications, whereas for Windows CE and Linux, it is supplemented with the 32-bit Memory Controller memory external with static dynamic RAM, SRAM or Flash memory.
The connection to a primary host is carried out via the dual-port-memory interface, which is configurable for stand-alone applications also as a 16-bit extension bus. Comprehensive peripheral functions, serial interfaces such as universal asynchronous receiver transmitter (UART), universal serial bus (USB), serial peripheral interface (SPI) and inter-integrated circuit (I2C), as well as the integrated graphic controller, permit a wide spectrum of applications. The central data switch and the four freely configurable communication channels with their own intelligence constitute the main characteristic of the netX as a “high-end” network controller.
The data switch connects via five data paths to the ARM CPU and the communication, graphic and Host controllers with the memory or the peripheral units. In this way, the controllers transmit their data in parallel, contrary to the traditional sequential architecture with only one common data bus and additional bus allocation cycles.
Two levels
The controllers of the four communication channels are structured on two levels and are identical to each other. They consist of dedicated arithmetic and logic units (ALUs) and special logic units that receive their protocol functions via Microcode. Two channels possess an additional integrated physical layer (PHY) for Ethernet. The Medium-Access-Controller xMAC sends or receives the data according to the respective bus access process and encrypts or converts these into Byte depictions.
The Protocol Execution controller xPEC compiles these into data packets and controls the telegram traffic. These are exchanged in direct memory access (DMA) blocks over the memory of the ARM. In addition, every channel has a dual-port memory available for status information or as local data picture. With the intelligent communication ALUs, the netX carries out the most varied protocols and protocol combinations and can synchronize them independently of the reaction time of the CPU.
The Sycon.net development software allows easy configuration and diagnostics of the fieldbus or real-time Ethernet system on netX. The netX can act as a master or a slave. After configuration, the resulting configuration file is made available to the application running on the netX. netX masters will be configured through Sycon.net. The active-X technology of Sycon.net enables the integration into OEM software.
