Category: VFD

Manufacturing floors have changed a lot over the past decade. Equipment that once needed constant manual supervision now runs on automated logic, adjusting to process conditions without anyone turning a dial. Variable frequency drives are a key part of that shift. A VFD on its own does a useful job controlling motor speed. But when it connects to a PLC through a communication protocol like Modbus, it becomes something more useful: a responsive, data-sharing part of the factory’s control system. This guide covers the practical side of that integration, written for engineers and plant managers who want to understand how the pieces fit together before starting a project. What a VFD Does and Why It Matters A VFD changes the frequency and voltage sent to an AC motor. That change controls how fast the motor spins, which direction it turns, and how much torque it puts out. The motor runs at whatever speed the job requires, rather than always running flat out. The energy savings are real. A pump running at 70 percent speed uses much less power than one running at full speed. But in a connected factory, the bigger gain is control. When the motor speed follows live process data, the system becomes far more stable and efficient. VFDs work across many applications. Pumps, fans, air compressors, conveyors, hoists, and injection machines all benefit from variable speed control. Running any of these at the right speed and at the right time reduces energy waste, lowers heat, and extends the equipment’s working life.                                                  Modbus: Simple, Reliable, and Widely Supported Modbus has been used on factory floors since the late 1970s. It is still one of the most common protocols in industrial settings today. The reason it stuck around is that it does its job without needing much from the people setting it up. The basic structure is straightforward. One master device, usually a PLC, sends requests to slave devices, which include VFDs. The drives act on those requests and send data back. That back-and-forth is the foundation of connected motor control. Two versions come up most often in VFD work: Both versions give the PLC the ability to send commands to the drive and pull status data back. That is the core of what makes integration work. How the PLC and VFD Work as a Pair The PLC handles the decision-making. It reads sensor data, runs through its logic, and sends outputs to field devices. The VFD is one of those devices. A standard cycle on a process line goes like this: That cycle repeats constantly. The motor tracks the process the whole time rather than sitting at a fixed speed that may or may not match what the process needs. What Modbus Gives You Access To Once the link between the PLC and VFD is active, a good range of data becomes available from a central point. Through the PLC or an HMI screen, you can read and adjust: Having all of that in one place means less time walking around checking panels and faster fault finding when a drive trips. Set Up Details Worth Getting Right Modbus is not complicated, but a few things need to be done properly, or the network will act up: Handling these points beforehand prevents most of the issues that tend to show up in the first few weeks after installation. The Case for Making It Happen Motors drive a large share of energy consumption in any factory. Pumps, fans, and compressors running at full speed when the process needs half that much is straight waste. Tying motor speed to actual process demand through VFDs and PLC control regularly cuts energy use by 30 to 50 percent on those loads. On the operations side, connected drives make fault diagnosis faster. Instead of guessing at what caused a trip, the maintenance team already has the fault code, the motor current at the time, and the recent alarm history. Downtime gets shorter, and production runs more evenly because the motors are doing what the process needs rather than ignoring it. Shenzhen VEIKONG Electric Co., Ltd: Build For Energy Smart Integration Shenzhen VEIKONG Electric Co., Ltd. has been manufacturing and supplying variable frequency drives for over 20 years. Their range covers high, medium, and low voltage applications and includes VEIKONG products serve pump systems, air compressors, hoists and cranes, injection machines, washing machines, and solar pump projects across global markets. Conclusion Linking VFDs to PLCs through Modbus is a practical, proven way to build better motor control into a factory. The setup is not overly complex when approached in the right order. Choosing drives that support industrial communication from the start makes the work easier and gives the system a solid foundation for the long term.

In almost every factory, plant, or industrial facility, motors are running somewhere. They drive pumps, move conveyors, spin fans, and power compressors. And whenever a motor is part of the system, someone eventually has to decide how to control it. Two devices come up in this conversation more than anything else: the Variable Frequency Drive and the Soft Starter. Both are common. Both are useful. And both get confused with each other far too often. This guide is for anyone trying to understand the real difference between the two, what each one actually does on the job, and how to pick the right one without overcomplicating the decision. What Is a Variable Frequency Drive? A Variable Frequency Drive, or VFD, is a device that controls how fast an AC motor runs by changing the frequency of the electrical supply going into it. More frequency means more speed. Less frequency means less speed. That relationship is what gives a VFD its name. The key thing about a VFD is that it works throughout the entire time the motor is running, not just at startup. You can set a motor to run at half speed, ramp it up gradually, slow it back down, or run it at full speed depending on what the process needs at any given moment. That level of control is what separates a VFD from most other motor control devices. Industries that deal with changing loads throughout the day get the most out of VFDs. Water treatment plants adjust pump speeds based on demand. HVAC systems slow fan motors down at night when less airflow is needed. Manufacturing lines speed up or slow down based on production requirements. In all these cases, running the motor at a lower speed during low-demand periods saves a significant amount of energy. What a VFD Can Offer? What Is a Soft Starter? A Soft Starter is a control system used for regulating the voltage input to the electric motor during the starting period. The current drawn by the electric motor when it is started at full voltage creates stress on the electric motor coils, shakes any mechanical elements connected to it, such as couplings or belts, and even creates problems for the supply side of the grid. A soft starter makes sure that the voltage input to the electric motor grows gradually, allowing the motor to gain its rotational speed gradually. Once the motor gains the desired speed, the soft starter completes its work. It remains idle until the next start. In some soft starter designs, the control is done even during stopping the motor, slowing down the motor gradually. This is beneficial in cases of using the soft starters in pumps where abrupt stops create excessive pressure in pipes. What can a Soft Starter offer? Where People Get Confused The confusion between VFDs and soft starters usually comes from the fact that both reduce startup stress. That overlap makes people think they are interchangeable. They are not. A soft starter only handles the start and, in some cases, the stop. Everything in between runs at full speed with no adjustment possible. A VFD handles the start, the stop, and everything in between. If your motor needs to change speed during operation, a soft starter cannot do that regardless of how it is set up. The other common point of confusion is cost. Soft starters are cheaper upfront and smaller in size. VFDs cost more initially but can recover that cost through lower energy bills over time, particularly in applications where motors run for long hours at partial loads. How to Pick the Right One The honest answer is simpler than most people expect. Ask yourself one question: does this motor need to run at different speeds during normal operation? If the answer is yes, go with a VFD. There is no workaround for variable speed control, and a soft starter will not get you there. If the answer is no and the motor always runs at full speed once it gets going, a soft starter is the practical choice. It handles the startup smoothly, costs less, takes up less space, and does exactly what the application needs. How Shenzhen VEIKONG Electric Co., Ltd. Helps You Make the Right Decision Shenzhen VEIKONG Electric Co., Ltd. has spent over 20 years manufacturing AC drives, VFDs, and soft starters for industrial customers in more than a dozen countries. The company is based in Baoan District, Shenzhen, China, and is recognized as one of the first independent AC drive companies in China. VEIKONG holds CE certification and operates under ISO 9001 quality standards. Their product range includes: Their products are used in petroleum, chemical processing, water supply, plastics, textiles, printing, hoisting, and building materials industries. Customers are spread across North America, South America, Europe, Southeast Asia, the Middle East, and Africa. At VEIKONG, the focus has always been on giving customers products that hold up in real operating conditions, backed by a technical team that actually helps when something needs solving. Conclusion A VFD and a soft starter are not the same device, and treating them as options for the same job usually leads to spending either too much or not enough. If your motor needs to vary its speed based on process demands, a VFD is the answer. If your motor runs at one fixed speed and you just need the startup to be smoother and gentler on equipment, a soft starter does that job well and costs less to buy and install. Getting this decision right protects your motors, keeps energy costs in check, and saves you from replacing equipment before its time. To explore VFD and soft starter options built for real industrial use, visit veikong-electric.com or get in touch with the VEIKONG team directly.