Abstract: This paper first provides a brief introduction to the structure and operation of the 6RA70 DC speed controller, its armature and excitation circuits, and its communication port. Then, it describes in detail the speed controller settings in master-slave control. The results show that speed and torque following are achieved. Keywords: 6RA70, Master Control [align=center][b]Siemens DC controller 6RA70 Master Control TANG Xing Long LIU Hui Kang SUN Kai[/b][/align] (Wuhan University of Science and Technology College of Information Science and Engineering, Wuhan, Hubei 430081) Abstract: This article first introduces the structure and working methods, the armature and excitation circuit, and the communication port of the Siemens DC controller 6RA70 Master Controller. Then, it describes the governor's settings in detail from the Master Control. The results show that the rate of follow and meet the purpose of torque. Key words: 6RA70, Master Control 1. Introduction to Siemens DC Controller 6RA70 Currently, with the development of AC speed control technology, AC drives have developed rapidly, but DC drive speed control still has a large number of applications in many situations. With the development of computer technology, past analog control systems are being replaced by digital control systems. In general-purpose fully digital DC speed controllers with microcomputers, various adjustment and control functions can be easily implemented with minimal or no hardware changes, relying solely on software support. Therefore, the reliability and application flexibility of general-purpose fully digital DC speed controllers are significantly superior to analog control systems. Currently, the 6RA70 series general-purpose fully digital DC speed controllers from the German company SIEMENS are the most widely used in China. 1.1 Structure and Operation Mode The SIMOREG 6RA70 series rectifier is a fully digital control device directly powered by a three-phase AC power supply. Its compact structure is used for armature and excitation power supply of adjustable speed DC motors. The rated armature current range is 15 to 2000A, and the rated excitation current is 3 to 85A. It can be expanded by paralleling SIMOREG rectifiers, and the output rated armature current can reach 12000A after parallel connection. The 6RA70 DC controller has been widely used in various industries, and the core components of the controller have been proven reliable both domestically and internationally, ensuring its reliability and safety. Depending on the application, a single-quadrant or four-quadrant operating device can be selected. The device itself has a parameter setting unit and does not require any other resistance. The device can complete the parameter setting. All control, regulation, monitoring and additional functions are implemented by the microprocessor. The setpoint and feedback value can be selected as digital or analog. The SIMOREG 6RA70 series rectifier is characterized by its small size and compact structure. An electronic box is installed inside the door of the device. The box contains the adjustment plate and can be equipped with additional boards for technical expansion and serial interface. Each unit is easy to disassemble and assemble, making device maintenance and service simple and easy. External signal connections such as switch input/output, analog input/output, pulse generator, etc. are achieved by plugging in terminal blocks. The device software is stored in Flash-EPPOM and can be easily replaced by writing to the serial interface of the basic device. [b]1.2 Power Section: Armature and Excitation Circuit The armature circuit is a three-phase bridge circuit:[/b] (1) The power section circuit of the single-quadrant operating device is a three-phase fully controlled bridge B6C. (2) The power section of the four-quadrant working device consists of two three-phase fully controlled bridges (B6)A (B6)C. The excitation circuit adopts a single-phase half-controlled bridge B2HZ. For devices with a rated current of 15-800A (current up to 1200A when the AC input voltage is 400V), the power section of the armature and excitation circuits is an electrically insulated thyristor module, so its heat sink is not energized. For devices with larger current or higher input voltage, the power section of the armature circuit is a flat thyristor. At this time, the heat sink is energized. All terminals of the power section are on the front. [b]1.3 Communication Port The following serial interfaces are available:[/b] (1) The UX300 plug is a serial interface that implements the USS protocol according to the RS232 or RS485 standard and can be used to connect the optional operation panel OP1S or debug SMOVIS via PC. (2) The serial interface on the main electronic terminal, RS485 two-core or four-core wire is used for the USS communication protocol or device-to-device connection. (3) Serial interface on the expansion board option terminal, RS485 two-core or four-core cable, for USS communication protocol or device-to-device connection. (4) PROFIBUS-DP via add-on card (option). (5) Connect to fiber optic cable via add-on card (option). [b]2. Siemens DC Controller 6RA70 Master-Slave Mode Parameter Setting 2.1 First, set the basic parameters of the DC motor in the 6RA70 device:[/b] P100=12.5 P101=220 P102=0.5 P103=0 P104=5000 P105=0.1 P106=5000 P107=0.1 P108=5000 P109=0 P110=1.738 P111=37.96 P112=390 P113=1 P114=10 P083=3 P790=5 P791=5 2.2 Main speed controller setting: P794.01=K6020 P794.02=K167 P794.03=K148 P794.04=K142 P794.05=K170 U117.01=B104 P687=0 P401=15% P433=K401 P654=1 P444=B17 P445=1 2.3 Slave Speed ​​Controller Settings: P625=K6002 P500=K6003 P687=B10 P661=K6100 After closing, when B10 is not pressed, the slave speed follows the master speed; as shown in Figure 1. [align=center] Figure 1[/align] When B10 is pressed, the slave torque follows the master speed; as shown in Figure 2. [align=center] Figure 2[/align] 3. Summary This article introduces the structure and operation mode of the 6RA70 DC speed controller, the armature and excitation circuit, the communication port, and makes corresponding settings for the master and slave speed controllers. Through debugging, the expected effect was achieved.