Why Choose Motion Controller Over a PLC?

Why Choose Motion Controller Over a PLC?

Laura Davis, Manufacturing Technology Insights | Thursday, September 09, 2021

Why Choose Motion Controller Over a PLC? One disadvantage of utilizing a programmable logic controller is that the programmer must manually create many control instructions. Without a certain, the roller motion will be precisely controlled by the servo motor.

FREMONT, CA: Machine automation is one of the most critical areas where automation operates. It is a type of industry in which machines are used to provide exact outputs, such as Programmable Logic Controllers (PLCs), encoders, servo motors, and other motion instruments.

These are control elements that influence the machine's overall behavior.

Motion Controllers

The PLC is the machine's principal controller, and it ensures that the machine runs smoothly. It is possible to call it the system's beating heart. It rotates a roller by controlling a servo motor through a servo drive; the motor is connected to a gearbox. Under the roller, a metal sheet is passing.

An encoder is built into the servo motor to provide position feedback. The PLC's job is to accurately pass the needed length and then stop the motor (roller) at that place as soon as the length is reached. The cutting part ahead will cut the length of the metal and then resume the motion once it is complete. The cycle continues.

The system uses closed-loop monitoring for control, which is interesting to see. Closed-loop monitoring is when a controller (PLC) transmits a command to an output device (servo motor) while also monitoring its response. In this case, the feedback is positioned. The servo motor will be operated to accomplish the set length based on mathematical calculations implemented inside the PLC (based on output pulses delivered and input pulses received from the encoder).

Why Should One Use a Motion Controller Rather Than A PLC?

One disadvantage of utilizing a PLC is that the programmer must manually create many control instructions. Without a certain, the roller motion will be precisely controlled by the servo motor.

However, elements such as scan time in a PLC play a significant role in this form of automation. The length of time it takes a PLC to execute a set of instructions, update IO status, and communicate is referred to as scan time. In the worst-case scenario, if there is a lag in scan time, the servo motor will stop at a late location rather than the anticipated place.

A motion controller is a type of PLC. Compared to a normal PLC for managing the motion of an element, they have many more advanced features. As a result, it is ideal for machine automation.

Although it can run in open-loop control, a motion controller is always employed under closed-loop control. On the other hand, closed-loop control is favored since it uses the instrument's feedback signal to take corrective action to bring the output (desired position) and input (actual position) into synchronization with each other, with no faults or errors.

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