Robot Controller:

Which Controller Fits Which Task?

These products provide an initial point of reference. Compatibility depends on the robot, motors, number of axes and required interfaces. The current RBTX range includes complete robot controls, motor controllers, motion controllers, modular DIN-rail systems and preassembled control cabinets.

When the exact combination is still open, suitable components can be compared on RBTX. The RBTXperts can also help match the controller, robot, software and tooling to the application.

What Does a Robot Controller Do?

The robot control system translates a program into physical movements and actions.

Depending on the system, it can perform tasks such as:

• Controlling motors and axes

• Calculating positions and speeds

• Saving and running motion sequences

• Switching grippers or tools

• Processing sensor signals

• Exchanging data with a PLC, machine or computer

• Reporting operating states and errors

• Coordinating several axes

A teach pendant, browser interface or programming software is used to set up the application. The actual motion calculation and motor control take place inside the controller.

Main Types of Robot Controllers

Motor Controllers for Individual Axes

A motor controller is relevant when one linear, rotary or positioning axis needs to be moved.

Typical applications include:

• Linear axes

• Rotary tables

• Format adjustments

• Feeding systems

• Lifting movements

• Additional robot axes

A compact motor controller may be sufficient when only a few positions are required and no complete robot kinematics need to be calculated.

Helpful starting information includes:

• Type of axis

• Motor being used

• Required movement

• Existing higher-level control

• Required inputs and outputs

Motion Controllers for Coordinated Axes

A motion controller coordinates several movement axes. It determines when and how the individual axes move.

Typical applications include:

• Gantry robots

• Cartesian robots

• Delta robots

• SCARA systems

• XY tables

• Multi-axis positioning systems

Robot motion control becomes especially relevant when several axes must move in a coordinated sequence rather than independently.

The main distinction is whether each axis only needs to reach separate positions or whether all axes must create one combined path.

Complete Robot Controllers

A complete industrial robot controller calculates and controls the motion of an entire robot kinematic system.

For an articulated robot, for example, the controller determines how several joints must move together so that the tool reaches the required position.

A complete control system is generally relevant when:

• An articulated or multi-axis robot is operated

• Cartesian target positions are programmed

• Several joints must move as one robot system

• Robot programs need to be stored and executed

• A programming and operating interface is required

• Grippers, sensors or machines need to be connected

For a single linear axis, a complete robot controller may provide more functions than the application requires.

Tool and Gripper Controllers

A tool controller does not operate the entire robot. It controls an attached gripper, vacuum system or process tool.

Depending on the tooling, it may handle:

• Opening and closing a gripper

• Adjusting pressure or gripping force

• Switching vacuum on and off

• Reporting positions or operating states

• Saving process parameters

• Exchanging signals with the robot controller

A tool controller normally supplements the main robot controller rather than replacing it.

Communication Modules

Communication modules connect the robot controller to a PLC, production machine or higher-level control system.

Typical signals include:

• Start permission

• Machine ready

• Workpiece detected

• Gripper closed

• Robot program completed

• Fault detected

A communication module is relevant when a specific industrial interface needs to be added.

The required module depends on the interfaces supported by the robot controller, PLC and machine. Common industrial controller platforms often combine motion control with digital connectivity and options for connecting external equipment.

Robot Control Cabinets and Preassembled Systems

A robot control cabinet houses control components, power supplies, terminals and other electrical equipment in one protected enclosure.

Preassembled systems can be useful when:

• Several motor controllers are required

• Multiple axes need to be operated

• Power supplies and connections should be housed centrally

• A clearly organized installation is preferred

• A customized automation system is being built

Depending on the product, motor controllers, power supplies, terminals or operating elements may already be installed.

Selection by System Layout

Robot Controller, Motion Controller or Motor Controller?

These terms are related but describe different functions.

A motor controller may be enough for one axis. A gantry with several coordinated axes may require a motion controller. An articulated robot generally requires a complete robot controller.

Robot Controller or PLC?

A PLC and a robot controller are not the same, although they often work together.

The PLC usually coordinates the wider machine sequence. The robot controller calculates and executes the robot movements.

A simple machine-tending sequence may work as follows:

1. The PLC reports that the machine is ready.

2. The robot controller starts the required program.

3. The robot picks up the workpiece.

4. The gripper is operated through an output or separate tool controller.

5. The robot controller reports that the task is complete.

Not every application requires an additional PLC. Some smaller robot cells can manage basic sequences directly through the robot control system.

What Is an Open Robot Controller?

An open robot controller provides options for integrating additional hardware, software or custom programs.

Possible characteristics include:

• Documented interfaces

• Support for common communication protocols

• Integration of external software

• Connection of additional devices

• Custom operator interfaces

• API access

“Open” does not mean that every device can be connected without configuration. The controller still needs to support the required hardware, protocol and functions.

Industrial controller platforms may use modular hardware and open or PC-based software architectures to support different production requirements and later system extensions.

Which Information Helps With the Selection?

A complete technical specification is not required for the first assessment.

Robot or Axis System

Useful information includes the manufacturer, model and number of axes. When no robot has been selected yet, a simple description of the required movement is enough to begin.

Planned Application

Typical examples include:

• Pick and place

• Machine loading and unloading

• Palletizing

• Moving a gantry or linear axis

• Inspecting workpieces

• Dispensing material

• Positioning a rotary table

The task indicates which motion, signal and communication functions are likely to be required.

Additional Components

When already known, the gripper, sensors, cameras, conveyor or production machine should also be included.

This helps identify the required connections and communication interfaces.

Operation and Programming

Depending on the system, the application may be configured through:

• A teach pendant

• Graphical software

• A web browser

• A PLC

• A connected computer

The operating concept should suit the application and the experience of the team responsible for setup and operation. Modern robot platforms may combine graphical programming, scripting, APIs and external-system integration within one software environment.

Missing details can be clarified during the next planning step. The RBTXperts can support the selection of compatible controllers, motors, software and interfaces.

Application Matrix for Robot Control Systems

Robot Operating Modes

Available robot operating modes depend on the manufacturer and control system.

The exact names and permitted behavior vary between controllers. The operating mode alone does not make an application safe.

Robot Control and Safety Are Different Functions

The standard robot controller manages movements and process sequences. Safety-related control functions must be considered separately.

Depending on the application, additional equipment may include:

• Emergency stop

• Safety-door monitoring

• Safety sensors

• Safety relays

• Safety controller

• Safely limited movements

The required protective measures result from the risk assessment of the complete system. A standard PLC or robotic controller is not automatically a safety controller.

Frequently Asked Questions About Robot Controllers

What is a robot controller?

A robot controller processes programs and signals, calculates movements and controls motors and connected components.

Which controller is suitable for one linear axis?

A compact motor controller is often sufficient for one linear or positioning axis. The exact choice depends on the motor and required control method.

Which controller is suitable for a gantry robot?

A gantry with several coordinated axes commonly requires a motion controller or several coordinated motor controllers.

When is a complete robot controller required?

A complete controller is generally required when several joints or axes form one robot kinematic system.

What is the difference between a PLC and a robot controller?

The robot controller mainly calculates robot movements. A PLC often coordinates the wider machine or production process.

What is robot controller software?

Robot controller software provides the programming, configuration and operating functions used with the control hardware. Depending on the system, it may support graphical programming, motion settings, interfaces and process monitoring.

Does a gripper need its own controller?

That depends on the gripper. Simple models may be switched through standard outputs, while other grippers require a dedicated control box.

When is a communication module required?

A communication module is relevant when an additional interface to a PLC, machine or industrial network is needed.

Is the controller always included with the robot?

That depends on the product package. Some robots are supplied with a controller, while others require a separate control solution.

Do all interfaces need to be known before making an inquiry?

No. The robot model, application and planned additional components usually provide enough information for an initial assessment.

Select the Right Robot Controller

Motor controllers, motion controllers, communication modules, tool controllers and complete robot control systems can be compared on RBTX.

Book a free expert video call

During a free 30-minute RBTXpert video call, the application, number of axes, robot model and required interfaces can be reviewed together.

Combine Compatible Components

The RBTXperts can help match the controller, motors, software, tooling and communication components.

Test the Application Before Purchasing

A feasibility test can help determine whether the robot, control system, software and other components work together as intended.

Request a Turnkey Automation Solution

For a complete automation project, the controller, control cabinet, operation, programming, interfaces and integration can be planned together.

Next step: Compare robot controllers, book a free consultation or request a complete automation solution.