How to Develop ethercat slave devices

As a new type of industrial Ethernet, ethercat is widely concerned with its openness, low system construction cost, and high speed. It can be used to develop slave station devices to introduce the network to the automation field, it will play a major role in promoting the automated transmission field. Ethercat network slave device is divided into simple slave device and complex slave device, simple slave device bit I/O slave station, generally, only the resources provided by the slave station interface controller can be implemented. The complex Slave Station Controller requires an application controller, which can access network data and execute specific applications.
In terms of hardware, we mainly consider the selection of the slave station interface controller and the slave station application controller. The slave station interface controller can be implemented by an ASIC chip or FPGA. The slave station interface controller can use the et1100 slave station controller of the company, which is an ASIC implementation method of the slave station controller, integrates all functions of the data link layer of the ethercat network. It has four network interfaces to connect to the ethercat network, and provides rich interfaces and application controllers for data exchange. For example, the slave application controller uses the ipv335 DSP chip, which is TI's latest 32-bit floating point DSP chip for industrial control. In software, the ethercat slave station network interface program completes the application layer protocol function. Since the ETG Association opens up its slave interface code, you only need to modify the code to meet personalized application requirements. You also need to write the master site configuration file and slave site description file.
The first 4 kb of ethercat memory in the slave station is the configuration register. Register Initialization is required before the slave station system runs. The initialization command frame is described in the configuration file of the master station. The ethercat configuration file is in XML format. The specific format is as follows:
 
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-Master site information (frame header definition)
-Broadcast addressing information (initialization command)
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-Slave Station Information (Communication Information)
-Type definition (mailbox/processdata)
-Slave Station initialization information
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The main site configuration file is divided into three parts:
(1) master site node: It mainly includes master site information and broadcast addressing information, the master site information mainly includes the master site name, target address, source address, Ethernet type, and broadcast addressing information. It initializes all slave sites in the same way as broadcast.
(2) slave node: This part can be divided into several slave nodes, it mainly includes the slave station information, type, slave station initialization information, and slave station information, including the slave station name, physical address, and location address. If the slave station type information is divided into "Mailbox ", the slave station is a complex device, the slave station is connected to the slave station application controller, if it is "processdata", the slave station is a simple device, and the I/O terminals are connected below. The slave station initialization information is used to configure some registers for a single slave station using location addressing and physical addressing.
(3) periodic data information: this information is the basis for data frames during the initialization process of the main station program.
The slave station description file is the resource information of the developed slave station. When the network is running, the master station sends data frames according to the slave station configuration file. The slave site description file contains the description of the slave site device developer, including the developer ID, name, and trademark information. The second is the device description, which contains the type group information of the developed device. The slave station description file should also contain the process input/output data definition and the mailbox data transmission mode definition.