When purchasing a multihead weigher, buyers usually compare weighing heads, target weight, speed, accuracy and hopper capacity. However, one technical factor is often overlooked: the control system.

The control system determines how the multihead weigher manages weight data, product feeding, hopper movement, combination calculation and communication with the packaging machine. Different control architectures can therefore affect machine configuration, feeding control, investment cost and production-line integration.

Choosing the right control system is not simply a matter of selecting the most expensive option. It should be based on the product, production requirements and automation goals.

TOUPACK provides both MCU-based and PLC-based control solutions for multihead weighers. Among the MCU-based solutions, TOUPACK has developed three different control architectures, internally named TIANPING, TIANJI and TIANZUN.

This guide explains the differences between these control approaches, the characteristics of each architecture, and the common troubleshooting methods used during multihead weigher operation.

What Does a Control System Do in a Multihead Weigher?

A multihead weigher is a coordinated weighing system rather than a simple scale.

During operation, the control system coordinates a sequence such as:

Product Feeding → Linear Vibration Feeding → Pool Hopper → Weigh Hopper → Combination Calculation → Selected Combination → Discharge → Packaging Machine

Individual weighing hoppers collect different portions of product. The control system receives the weight data, calculates possible combinations and selects a combination close to the target weight. The selected weighing hoppers then open and discharge the product into the collection hopper or directly into the packaging machine.

TOUPACK PLC-controlled multihead weighers use the controller to perform combination calculations, select a suitable combination and control the corresponding weighing hoppers for discharge.

The control system therefore coordinates several important functions:

• Weight data acquisition
• Combination calculation
• Vibration feeding
• Hopper movement
• Motor control
• Equipment communication
• Parameter management
• Operating status monitoring

In simple terms, the control system is the control center of the multihead weigher.

MCU vs. PLC: What Is the Difference?

MCU and PLC are two different approaches to implementing machine control.

MCU-Based Control

An MCU, or microcontroller unit, is used as the core controller in three MCU-based control architectures developed by TOUPACK.

These architectures are internally named:

TIANPING
TIANJI
TIANZUN

Although their hardware structures and control methods differ, all three are designed specifically for multihead weighing applications.

Typical advantages of MCU-based control include:

• Dedicated control architecture
• Application-specific design
• Compact system structure
• Cost-efficient implementation

PLC-Based Control

A PLC, or Programmable Logic Controller, is an industrial controller widely used in automation systems.

For a multihead weigher, PLC can perform functions such as:

Weight data processing
Combination calculation
Motor control
Vibration control
Equipment communication
Parameter management

TOUPACK PLC-controlled TY-1A-P series is designed as an automatic weighing machine using PLC control, with high-speed operation, high accuracy, stable performance and expandable functions according to customer requirements.

The key point is that PLC should not simply be described as a “higher-level MCU.”

MCU and PLC represent different control approaches. PLC can be particularly suitable when industrial automation, equipment communication and broader system integration are important.

Three MCU-Based Control Architectures Developed by TOUPACK

TOUPACK has developed three MCU-based control architectures for different machine configurations and application requirements.

They are internally named:

TIANPING
TIANJI
TIANZUN

These names represent different control architectures rather than three completely different weighing principles.

The core weighing process remains based on combination weighing. The major differences are found in the hardware structure and vibration-feeding control method.

TIANPING: Integrated MCU Control Architecture

TIANPING uses an MCU-based control architecture with a relatively integrated hardware structure.

The main structure consists of:

One main control board and One hopper control backplane

The hopper control backplane directly connects to:

AD boards
Hopper-door stepper motor drives
Linear vibrator drives

Compared with the TIANJI architecture, more control functions are integrated into the hopper control backplane.

The vibration feeding system uses a controlled-rectifier method based on the frequency of the power supply.

Key Characteristics of TIANPING

Integrated control structure

More control functions are integrated into the control backplane.

MCU-based control

The system uses an MCU as the core controller.

Cost efficiency

The simplified hardware structure helps reduce system cost compared with more complex control architectures.

TIANPING is therefore suitable for customers who need a practical MCU-based control solution for appropriate multihead weighing applications.

TIANJI: Modular MCU Control Architecture

TIANJI is also an MCU-based control solution, but its hardware architecture is more modular.

The main structure includes:

One main control board

One hopper CPU backplane

One hopper-door stepper motor driver backplane

One linear vibrator driver backplane

The hopper CPU backplane carries the CPU boards corresponding to the weighing heads.

Each weighing head has an independent control unit consisting of:

AD module
Hopper-door stepper motor drive
Vibration drive

Different control functions are therefore distributed through dedicated modules.

The vibration feeding system uses a controlled-rectifier method based on the frequency of the power supply.

What Makes TIANJI Different?

The main difference between TIANPING and TIANJI is the hardware control architecture, rather than a completely different weighing method.

TIANPING uses a more integrated structure, while TIANJI uses a more modular structure.

This distinction can be important when evaluating machine architecture, maintenance requirements and overall system configuration.

TIANZUN: MCU + SPWM Vibration Control

TIANZUN uses an MCU-based architecture with a structure similar to TIANPING.

The main structure consists of:

One main control board

and

One hopper control backplane

The hopper control backplane directly connects to:

AD boards
Hopper-door stepper motor drives
Linear vibrator drives

The major difference is the vibration feeding control method.

TIANPING and TIANJI

The vibration feeding system uses a controlled-rectifier method based on the power supply frequency.

TIANZUN

The vibration feeding system uses SPWM technology.

SPWM allows the system to modulate different frequencies according to product feeding requirements.

This provides a more flexible way to control vibration frequency.

In a multihead weigher, feeding conditions directly affect individual hopper weights and combination performance. The control system provides parameters such as main vibration amplitude, linear vibration amplitude and vibration time to adjust the feeding process.

The system also provides AFC functions for automatic vibration-amplitude adjustment based on combination-head information or individual hopper weight.

Why Does SPWM Matter?

The purpose is not simply to make the vibrator run faster.

The goal is to achieve a more suitable feeding condition for the product.

A suitable feeding condition helps balance:

Feeding quantity
Individual hopper weight
Combination efficiency
Discharge continuity

This is the key technical characteristic of the TIANZUN architecture.

PLC Control: When Should Buyers Consider It?

PLC provides another control option for customers who require an industrial controller.

TOUPACK PLC multihead weigher systems support functions such as parameter management, manual testing, calibration, production records and equipment communication.

The PLC system can also receive discharge-request signals from packaging equipment and coordinate the discharge process according to the selected signal mode.

PLC-based control can therefore be considered when a project requires:

Industrial automation

Communication with other equipment

Production-line integration

Future system expansion

For a complete automatic weighing and packaging line, the controller may need to communicate with upstream feeding equipment, packaging machines and downstream inspection systems.

In these applications, PLC can provide a suitable industrial control architecture.

MCU vs. PLC: Cost and Application Comparison

For the three MCU-based architectures developed by TOUPACK, the relative cost is generally:

TIANPING < TIANJI < TIANZUN

The differences mainly come from hardware architecture and control technology.

PLC-based solutions generally involve higher controller and integration costs, although the final cost depends on the PLC configuration, HMI, communication requirements and overall project design.

For the three MCU architectures, the overall performance positioning can be summarized as:

TIANPING ≈ TIANJI < TIANZUN

PLC should be considered as a different industrial control route rather than simply placed above the MCU architectures in a linear performance ranking.

How Should You Choose the Right Control System?

There is no single control system that is ideal for every multihead weigher.

The selection should start with the actual production requirements.

Product Characteristics

Consider the product's flowability, shape, moisture, stickiness and feeding behavior.

Target Weight

The target weight and weighing range affect the machine configuration and operating parameters.

Production Speed

The control system needs to work together with the required weighing and packaging cycle.

Feeding Requirements

If vibration feeding is a critical part of the application, the available vibration-control method should be evaluated carefully.

Automation Requirements

If the machine is integrated into a larger automatic production line, communication and system-integration requirements should be considered from the beginning.

Budget

A higher-priced control system is not automatically the most suitable option. The goal is to select the required control capability without unnecessary investment.

Control Functions for Daily Operation

A control system should do more than calculate combinations.

It should also provide tools to help operators monitor machine status and adjust operating parameters.

TOUPACK multihead weigher control systems provide functions including:

Manual testing
Parameter adjustment
Calibration
AD communication testing
Production record management

The manual testing function can individually check the main vibrator, linear vibrators, pool hoppers, weighing hoppers and collection hopper.

The AD test function can display the communication status of AD modules and corresponding weighing data, helping technicians identify abnormal control units.

Production records can also be stored and reviewed through the control interface.

These functions make daily operation and troubleshooting more structured.

Common Multihead Weigher Problems and Troubleshooting

Even when the mechanical components are functioning normally, a multihead weigher may require parameter adjustments due to changes in product flow, feeding conditions or operating settings.

The following troubleshooting points are based on the technical documentation for TOUPACK multihead weighers.

Individual Hopper Weight Is Too High

If an individual weighing hopper receives too much product, check the feeding parameters.

Depending on the AFC mode, possible adjustments include:

Reducing linear vibrator amplitude

Adjusting the average combination-head setting

Adjusting the individual hopper weight ratio

The technical documentation recommends adjusting linear vibrator amplitude to improve feeding uniformity.

Individual Hopper Weight Is Too Low

If the weight in an individual hopper is too low, check whether the cause is:

Insufficient feeding

or

Insufficient product supply

Appropriate adjustment of linear vibrator amplitude may help, but operators should also check the upstream feeding system and product supply.

The objective is stable feeding rather than maximum vibration.

Displayed Weight Does Not Match Actual Weight

When displayed weight differs significantly from actual package weight, several factors should be checked:

Zero-point drift

Calibration

Weight correction settings

Residual product in the weighing hopper

The technical documentation recommends checking power grounding and performing initial calibration when zero drift occurs. It also provides adjustment methods for correcting consistent overweight or underweight conditions.

If product remains in the weighing hopper after discharge, motor settings and hopper timing may also need adjustment.

Product Discharge Is Not Continuous

If the discharge cycle has a noticeable pause, one possible reason is that some hoppers used for the previous combination have not completed refilling before the next combination is calculated.

According to the technical documentation, adjusting the upper and lower weight deviation values can help improve discharge continuity under appropriate conditions.

This can be particularly important when the multihead weigher is working with a high-speed packaging machine.

Packing Speed Gradually Decreases

If the machine runs normally at first but gradually becomes slower, check the AFC settings.

The system supports:

AFCT, which tracks the number of combination heads and adjusts linear vibration amplitude accordingly.

AFCI, which uses individual hopper weight as the tracking basis and adjusts the vibration amplitude of individual linear vibrators.

The technical documentation provides recommended parameter ranges for these AFC modes.

This highlights an important operating principle:

Higher vibration does not necessarily mean higher efficiency.

The objective is stable and appropriate feeding.

Combination Success Rate Is Too Low

If the machine is running but the combination success rate is below the expected level, check:

Linear vibrator amplitude

Average combination-head setting

Upper and lower weight deviations

Uneven feeding or unsuitable product distribution can reduce the number of successful combinations.

The technical documentation recommends adjusting vibration and weight-deviation parameters according to actual operating conditions.

Hopper Door Makes Excessive Noise

If a hopper door produces excessive impact noise when closing, the motor closing speed may be too high.

The motor operating mode can be adjusted to optimize hopper movement.

The control system supports different motor modes and adjustable operating parameters for the pool hopper, weighing hopper and collection hopper.

Hopper Door Opens Too Quickly or Fails to Close

The manual testing function can be used to check the relevant hopper.

Operators can individually test:

Pool hopper

Weighing hopper

Collection hopper

and other machine units.

If the problem occurs on only one hopper, the corresponding position-detection components should also be checked.

Control Module Communication Error

The AD test function can be used to check communication status between control modules and weighing units.

When a unit control board communication error occurs, the relevant control unit should be inspected.

The technical documentation identifies control-board communication failure as a specific fault condition and provides corresponding troubleshooting guidance.

This type of diagnostic function helps technicians narrow down the problem before replacing components.

What Should Buyers Ask a Multihead Weigher Supplier?

When comparing multihead weighers, it is useful to ask more than:

What is the weighing accuracy?

A more complete technical evaluation should include:

What control architecture does the machine use?

How is vibration feeding controlled?

How are individual weighing units monitored?

Can the system identify communication errors?

How are operating parameters adjusted?

How is calibration performed?

How does the system communicate with the packaging machine?

Can the control system be integrated into a larger automation line?

These questions help buyers compare the actual capabilities of different machines rather than comparing only price and weighing-head count.

Why Control Architecture Matters

The control system is not an isolated electronic component.

It connects:

Weighing

Feeding

Combination Calculation

Hopper Movement

Discharge

Packaging Communication

into one operating process.

This is why different multihead weighers can use different control architectures even when their mechanical structures appear similar.

One customer may prioritize:

Cost efficiency

Another may prioritize:

Modular architecture

Another may need:

More flexible vibration control

Another may require:

Industrial PLC integration

The best control architecture is therefore the one that matches the actual production requirements.

TOUPACK Multihead Weigher Control Solutions

TOUPACK develops different MCU-based and PLC-based control solutions rather than applying one control architecture to every application.

The three MCU-based architectures—TIANPING, TIANJI and TIANZUN—represent different approaches to hardware structure and vibration control.

PLC provides an alternative industrial control architecture for projects requiring industrial automation and broader system integration.

This allows the control system to be selected as part of the complete weighing solution.

The machine configuration can be considered together with:

Product Type

Target Weight

Production Speed

Feeding Characteristics

Packaging Method

Automation Requirements

Conclusion

The control system is an important part of multihead weigher selection.

MCU-based control provides a dedicated control approach for weighing equipment, while PLC provides an industrial control architecture for applications requiring broader automation and system integration.

Within the MCU-based solutions developed by TOUPACK:

TIANPING uses a more integrated MCU architecture with a focus on cost efficiency.

TIANJI uses a more modular MCU architecture.

TIANZUN combines MCU control with SPWM-based vibration-frequency control for more flexible vibration feeding management.

PLC provides an industrial controller-based solution for applications where industrial automation and system integration are important.

The right choice should not be based simply on which control system costs more.

Instead, consider:

Product + Target Weight + Production Speed + Feeding Characteristics + Automation Requirements + Integration Needs

TOUPACK provides customized multihead weighing solutions with MCU- and PLC-based control options, helping customers select an appropriate balance of control architecture, feeding performance, automation and investment cost.

Tell TOUPACK your product type, target weight and required production speed to discuss a suitable multihead weigher and control system.