Abstract : Automation network communication is an important part of factory automation control systems. A complete control system is composed of a management layer based on industrial Ethernet and a control layer based on Profibus-DP. This paper starts with modern automation control networks and conducts an in-depth analysis and research on the communication network consisting of four 6RA70 PLCs, one 6SE70 PLC, two remote I/O stations, and a Siemens S7-400 PLC. A control word control scheme for AC/DC drive devices is proposed. This scheme utilizes network transmission of control words to improve system performance, greatly simplify wiring, and increase work efficiency. Keywords : Industrial Ethernet; Fieldbus; DC speed controller; AC speed controller 1 Overview This paper studies and discusses the application of modern automation control networks. The system has two operator stations. The host computer communicates with the PLC via industrial Ethernet. Both host computers are equipped with Ethernet cards (CP1613). The management layer uses industrial Ethernet communication, and the control layer uses Profibus-DP fieldbus communication. The Siemens S7-300 PLC and S7-400 PLC serve as PLC control stations. DC drives include the Siemens 6RA70 series and Emerson CT Mentor series, while AC drives include the Siemens 6SE70 series and Yaskawa CIMR-G7 series. Two ET200M remote I/O stations are also included. This article will introduce the communication network formed by four 6RA70 units, one 6SE70 unit, two remote I/O stations, and the Siemens S7-400 PLC. 2. Device Introduction 2.1 PLC Communication and Remote I/O Stations The Siemens S7-400 is a large PLC. Here, the communication module CP443-1EX11-0XE0 is connected to the OSM62 switch, and the operator console computer's network card is connected to the OSM62, thus fulfilling the hardware requirements for industrial Ethernet. The ET200 is a remote I/O station. To reduce signal cable laying, different types of I/O stations, such as ET200M, ET200L, ET200S, and ET200X, are placed near the equipment. The ET200M is suitable for use when there are a large number of remote station I/Os. The specific configuration of the two ET200M units in the advanced sports center is detailed in the system configuration section. The key to communication between the ET200M and the PLC lies in the network configuration and the setting of the ET200M's address. When configuring the ET200M's input/output modules, start with slot 4; slot 3 should be left empty. The configured module type must match the hardware. During configuration, the module selected by the programmer can be placed in the corresponding green slot. When configuring the PROFIBUS-DP network, the ET200M's address should match the DIP switch. In the network, the address of each device is like the key to unlock the door; the address must be set correctly. The ET200M is connected to the PLC using a Profibus-DP cable. If it is a network terminal station, the terminating resistor of the DP connector must be switched to ON. 2.2 The AC drive system uses the 6SE70 series frequency converters. This series uses nested technology, and technical parameters can be nested as needed. A CBP2 communication board (i.e., Siemens Profibus-DP communication board) is also added. Siemens vector control frequency converters have a wide allowable voltage fluctuation range, small size, powerful communication functions, and are 100% compatible with DC drives. The frequency converter control settings include internal and external control. When the operator selects internal control, the PMU operating panel is active, and the control signals on the control cabinet are inactive. In this control mode, the start and stop of the frequency converter are controlled by "1" and "0" on the PMU panel. When the operator selects external control, the control signals on the control cabinet door are active. Switching between internal and external control is done by changing the value of parameter P554; a value of 5 enables internal control. The DC drive uses the 6RA70 series, which also employs parameter nesting technology and includes an additional CBP2 communication board. The control cabinet door has start, stop, and fault recovery buttons. The start button requires a self-holding function, and terminal 39 serves as the stop button. The self-holding function is set as follows: P444=17, P445=1. The AC/DC devices are connected to the network using a Profibus-DP cable. The DP interface is plugged into the CBP2 communication board, and the network address is set in P918. 3 System Application 3.1 System Configuration Network hardware configuration: The programming software for the Siemens S7-400 PLC is STEP 7. Start STEP 7, open the wizard, and generate a project according to the wizard prompts. Open the hardware configuration editor (Hardware) for this project to perform hardware configuration. The hardware configuration of this project is shown in Figure 1. [align=center]Figure 1 Hardware Configuration Diagram[/align] The Profibus-DP network operates in a master-slave mode, with the CPU as the master and the AC/DC drive controller and distributed I/O as slaves. Duplicate addresses are not allowed for each slave. The distributed I/O module configuration becomes the input/output signal of the entire network. In the configuration editor, click ET200M, place the module in the configuration slot of the distributed I/O module, and design the initial address of the module when configuring ET200M. Figure 2 shows the configuration of the ET200M on the system's #1 operator console. The specific address allocation can be found in the figure. [align=center]Figure 2 ET200M Configuration on #1 Operator Console[/align] 3.2 Network Communication Data In the Profibus-DP pre-file, the data structure of the periodic channel is defined as a parameter process data object (PPO). It is divided into two parts—the PZD part and the PKW part—and can be sent separately using messages. The PZD section, or process data section, includes the device's control word, setpoint, status word, and actual value; the PKW section, or parameter section, is used to read and write the device's parameter values. The Siemens S-400 PLC sets and resets the 16 bits of the control word via the Profibus-DP bus, thus controlling the motor. The data exchange format between CBP2 and 6RA70 is shown in Figure 3. [align=center] Figure 3 Schematic diagram of 6RA70 data exchange[/align] 3.3 PLC program [align=center] Figure 4 Schematic diagram of DB1 address[/align] To achieve communication between the CPU master station and the network slave station, we must write the correct program on the master station. This requires calling SFC15 (DPWR-DAT). First, create DB1 and write the address in DB1. The DB address of the advanced motion center is shown in Figure 4. Write the communication program in FC3. The system program is shown in Figures 5 and 6. During communication, while the program performs closing/opening and running enable on the motor, the device's power closing/opening terminals and running enable terminals must always remain at a high level. Otherwise, communication will fail. When the hardware conditions are met, the CPU will be set to RUN. When we change the switch status of consoles #1 and #2, the value of n733 will change accordingly, indicating that the communication data transmission is successful. The bytes corresponding to console #1 are IB12～IB15, and the bytes corresponding to console #2 are IB20～IB23. The communication control words for the switch control of console #1 are I13.0→B3200…I13.7→B3207, I12.0→B3208…I12.7→B3215; I14.0→B3308…I14.3→B3311. The control words for the switch control device of console #2 are I20.0→B34008…I20.7→B3415, I21.0→B3400…I21.7→B3407; I22.0→B3508…I22.3→B3511. 5. Summary Industrial Ethernet is an international standard, and PROFIBUS-DP is one of the most widely used fieldbuses in China. We can connect the management and control layers via Ethernet, and organically link field devices with this network communication capability via Profibus-DP. In this way, the host computer system and field devices form a complete factory automation control structure through the network. We applied it to the drive system of the Advanced Sports Center at Wuhan University of Science and Technology. After more than six months of operation, the system's advanced design and control system operation on two control panels demonstrate its effectiveness. The Advanced Sports Center at Wuhan University of Science and Technology is a key research area for doctoral programs and an engineering center of the Ministry of Education. Automation network control is a key research area in modern automation and has a promising future.