Articles on: Learning & FAQ

How Does the Upper Computer Obtain the Encoder Position (Stepper and Servo)?

The upper computer obtains the servo motor encoder position

Servo encoders can be connected to the upper computer through a DI/DO circuit (digital input/output circuit) formed by the motor's rear control board to exchange signals.

When using a PLC to control a servo or stepper system, it is not usually necessary to use encoder feedback to determine position. Position pulses can be issued to the servo drive using PLC instructions, and the drive's internal position loop can be used for position feedback.

Generally, servo drives have a pulse division output function. If the upper computer also needs to receive encoder information separately, the encoder pulses fed back by the motor can be output after division, as a reference for the upper system's closed loop.

The pulse division output interface for the T6 series is CN6, and the wiring diagram is shown below:

The upper computer obtains the stepper motor encoder position

In the stepper motor closed-loop system, the upper computer controls the motor by sending pulses to the driver. The pulse frequency is used to control the speed, and the pulse number is used to control the position. At the same time, the driver will also send the pulse number to feedback the position and speed of the motor to the upper computer.

But to realize this kind of control, the PLC is required to be bus type, which can be 485 bus or Ethercat bus. At the same time, the driver also needs to support these two bus control methods. In this way, information can be obtained directly through messages.

Regarding the encoder of stepper motors: The stepper motors we sell all use incremental encoders with turn feedback. Some encoders have Z signals and some do not. Without the Z signal, there is no zeroing function and the position cannot be read. For encoders with Z signals, a zero position program needs to be written in the host computer to achieve position reading and zero return.

Updated on: 31/05/2024

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