Pulse Control or Bus Control for Stepper Motor
Stepper motor is to receive the pulse current to achieve speed, position and direction of control. The number of pulses determines the position of the stepper motor, the pulse rate determines the motor speed and pulse direction determines the steering of motor. The control mode of most stepper motor is using PLC to send pulses to the driver and then drive motor to operate. Pulse mode has been around for several decades, and for some applications requiring high frequency, the pulse type can no longer meet the requirements, and it needs to be controlled by the bus type.
For the applications that a lot of motors need to be used, such as many medical devices have a twenty or thirty axis, if using a pulse type stepper motor is not easy to control. Generally, a PLC can control up to six or seven axes, therefore, multiple PC will be required because of many motors, and the volume of space requirements are relatively large, while most of the medical equipment volume is small and compact. In addition, it is difficult for the motors to have more pulse type wiring, and the signal interference problem can cause the instability of the equipment. If we use the bus type, we only need two signal lines and power lines to connect all the motors in series. The design and installation are very convenient, and there will not be a lot of signal interference in wiring.
Some of the machinery itself with the host computer above, if you use the pulse type can not play the role of the host computer, but also need a PC or motion control card to control the stepper motor drive system. However using bus type can be directly controlled by the host computer, it has has the professional performance of motion control card mode, and the cost and volume has great advantages than pulse control mode.
Some products require a torque mode during the movement, for example, some of the screw locking machine use the torque mode. The pulse type can not control the motor current to adjust the torque, but the bus type can do it.
Compared with the pulse type, bus control type is not only smaller in volume, the writing of the control program is much simpler than the PLC ladder program, but also the motor current, voltage and temperature can be feedback all the time. It realizes the simple control of current and subdivision, s-shaped acceleration and deceleration, analog quantity, synchronization instruction, off-line control and so on. In general, the bus type has many new features and no disadvantages for the pulse type, which is the development direction and trend of stepper motor motion control in the future.