Technical Knowledge

An EtherCAT bus motor-PMM series integrated servo motor
Release Date : 2020-06-09 18:11:53



The EtherCAT bus motor refers to a motor that can be connected to the motion controller through the EtherCAT/CANOpen protocol (DS402) and does not require software to run. Moreover, the communication delay of a servo axis is only 1us, which can basically realize synchronous operation and improve the accuracy of the servo control system.





Characteristics of EtherCAT bus motor:
 
1. High precision, at the same time optional cable redundancy and functional safety protocol. It provides a new solution for the real-time and flexibility of the motion control system.
 
2. One frame to the end
1) The maximum data capacity of one frame of EtherCAT is up to 1470 bytes. Data can be modified or added during message transmission without stacking, buffering or disassembling/combining
2) Each node directly uses hardware to perform calculations, without the need for software participation, which greatly reduces the message delay. The communication delay of a servo axis is only 1us
 
3. Synchronized clock
1) Each EtherCAT slave has a clock mechanism inside the slave controller ESC, called slave clock
2) There is also a clock mechanism inside each EtherCAT master station, called the master clock
3) The EtherCAT bus network regards the first slave station clock as the reference clock and uses the reference clock as the system clock of the entire system. All clocks including the master station clock are synchronized to the reference clock
4) In the EtherCAT bus network, the distributed clock can make all EtherCAT bus devices use the same system time through the synchronization signal (SYNC signal), thereby controlling the synchronous execution of the tasks of each device;
5) The SYNC signal transmission cycle is the synchronization cycle
 
In the past, the servo motor driver and the hybrid stepper motor were separated from the controller. The overall size of the motor is large, and the anti-interference is poor. The wiring is complicated, which relies heavily on the hardware system, and the controller has high requirements. . For some equipment to realize multi-axis linkage, the cost is relatively high, the network is complex, and debugging is difficult, which is not convenient for equipment maintenance and repair.
 




The combination of EtherCAT bus technology and integrated servo motor driver technology not only improves the communication efficiency, but also increases the control effect of the servo motor. At the same time, it also meets even the characteristics of ETHERCAT, including high-precision device synchronization, optional cable redundancy and functional safety protocols.
 
Main features of PMM series integrated servo motor:
 
1. Modular and highly integrated design, quick layout and installation, eliminating the matching process between driver and motor, reducing the cost of fieldbus and reducing the cost of use
2. Connected to the controller through the EtherCAT/CANOpen protocol (DS402), each node directly uses hardware to perform calculations, without the need for software participation, which greatly reduces the message delay time. Transmission rate: 2x100Mbps (full duplex) The hardware delay of a servo axis is only 1us
3. Control accuracy reaches ±1rpm and ±1pulse, 1ms real-time response period, with excellent control performance and good positioning accuracy.
 
In short, the integrated servo motor controlled by EtherCAT bus is an integrated intelligent motor with high performance, low cost and simple application.
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