Advanced PLC Functions For Electric Axis Motion Control

Cutting-edge Technology Functions for High-Performance Motion Control

MotionProX: The Ultimate Precision Motion Control Solution for Electric Axes

Introducing MotionProX – the all-in-one motion control solution for your electric axis. Designed for precision and versatility, MotionProX delivers exceptional control over position, speed, and acceleration, making it the perfect choice for a wide range of industrial applications.

Why Choose MotionProX?

Universal PLC Compatibility: Forget about specialized technology CPUs! MotionProX runs seamlessly on real-time PLC platforms including Siemens S7, Siemens TIA Portal, Rockwell Studio AIO, Rockwell RSLogix 5000, Rexroth IndraWorks, B&R Automation Studio, and Beckhoff TwinCAT, all while delivering the same high performance across the board.
Seamless Integration with Existing PLC Programs: The MotionProX PLC function can be easily purchased and directly integrated into your existing PLC programs. This allows for effortless scaling and enhancement of your current automation systems without the need for extensive reprogramming or system overhauls.
Simplified Commissioning and Parameterization: With comprehensive input/output documentation and practical examples, MotionProX makes commissioning and parameterization incredibly straightforward. This reduces setup time and ensures a smooth transition from installation to operation, empowering your team to get up and running quickly with minimal effort.
Multiple Control Modes: Operate in Absolute Movement Mode, Relative Move Mode, Jog Mode, or Motor Speed Mode. Each mode is tailored to specific motion control requirements, providing you with maximum flexibility to suit your application.
Precision and Customization: MotionProX accepts separate setpoints for position, speed, acceleration, and jerk, allowing for highly precise and customizable control configurations.
Immediate Stop for Safety: Equipped with a Stop input, MotionProX ensures immediate halts with customizable deceleration, protecting both your equipment and personnel.
Advanced Trajectory Generator: At the heart of MotionProX is a sophisticated internal trajectory generator, ensuring smooth, accurate control of your axis’ movement, speed, and acceleration for optimal performance.

If your operations demand high precision, flexibility, and safety in motion control, MotionProX is the perfect solution. Elevate your automation systems with advanced technology that delivers results every time. Contact us today to learn more!

Description

The MotionProX controller is a versatile and advanced technological PLC function block designed for precise position, speed and acceleration control of an electrical axis. This function plays a crucial role in determining the desired rotational speed (setpoint) for an electrical motor, ensuring that the linear axis achieves the specified position, speed and acceleration set values, depending on the selected operational mode.

This function can be operated in various modes, including absolute movement mode, relative movement mode, jog mode and motor speed mode. The motor speed control mode is particularly suited for applications where position feedback to the PLC program is not required, like conveyors, pumps, fans, or other motion-driven applications.

Each mode is tailored to specific motion control needs, providing flexibility and precision in a wide range of applications. Additionally, the function is equipped with a stop input, allowing for an immediate motor stop with an adjustable deceleration rate at any given moment, ensuring safety and control. The MotionProX function is designed with separate inputs for setpoints of position, speed, acceleration and jerk for each operational mode. This allows for highly customized and flexible control configurations tailored to specific application needs. At the core of this function is an internal trajectory generator, which enables highly accurate and smooth control of the linear axis’s position, speed and acceleration. This sophisticated technology ensures optimal performance, making it an essential component in advenced motion control systems. Compatible with various PLC platforms like Siemens S7, Siemens TIA Portal, Rockwell Studio AIO, Rockwell RSLogix 5000, Rexroth IndraWorks, B&R Automation Studio, and Beckhoff TwinCAT, MotionProX provides the same high performance on any platform.

	1	2	3	4
Operation modes	Absolute movement position control	Relative movement position control	Jog Movement with Push Button	Motor Speed Control

Table 1: Different operation modes of the MotionProX function bock

Block Diagram

Inputs Description

GenPar
	SampleTime
	MaxOut
	MinOut
	SupImpCtrl
	Digits

GenPar → SampleTime - Calling frequency of the controller -REAL-

The sample time, in second, of the cyclic interrupt task of the plc at which the function is running. A higher sampling frequency allows for more precise control.

GenPar → MaxOut - Maximum Output, -REAL-

Is used to define the upper limit for the CtrlOut output, which represents the rotational speed setpoint for the electric motor.

GenPar → MinOut - Minimum Output, -REAL-

Is used to define the lower limit of the CtrlOut to a specific value.

GenPar → SupImpCtrl - Superimposed Contoller input, -REAL-

The SupImpCtrl input is intended for applications where multiple axes need to be synchronized in position or speed or where the torque of the electric motor must be manipulated by a superimposed controller. This input allows an external controller to manipulate the position or speed of the linear axis or the torque of the motor, enabling precise coordination and adaptive control in complex systems. The schematic of the signal flow, as depicted in the accompanying image, illustrates how the SupImpCtrl input interacts with other components within the control system, ensuring that the external controller’s commands are effectively integrated into the overall motion control process.

Figure 1

GenPar → Digits - Resolution of the calculated movement trajectory, -INT-

The Digits input is an integer value that determines the resolution of the decimal places for the calculated movement trajectories. This setting controls the precision of the trajectory calculations, ensuring accurate motion control. A value of 4 is recommended, which provides a good balance between precision and computational efficiency, allowing the function to generate smooth and accurate movement paths.

ParMovAbs
	TgtPos
	MaxSpdSetPnt
	MaxAccSetPnt
	JerkSetPnt

ParMovAbs → TgtPos - Position setpoint for absolute movement, -REAL-

The input allows users to specify the desired target position for the linear axis. It can be defined in any unit appropriate for the application (e.g. meters, centimeters, millimeters, micrometer). When the ExeMov input recognizes a rising edge, the function generates a trajectory from the current position to the specified target. The internal position controller ensures that the linear axis follows this trajectory accurately.

To operate the function in absolute move mode, the Mode input must be configured with a value of 1. This setting ensures that the function interprets the ParMovAbs input as setpoint. Important: It is essential to understand that any changes of the TgtPos , MaxSpd , MaxAccSetPnt and JerkSetPnt during axis movement are internally ignored by the function block. The function block responds to changes only when PosTrj matches TgtPos . The Busy ouput serves as an indicator of the block’s readiness: When the Busy output of the block is logicaly True , it indicates that the axis is in motion and the controller will not respond to new setpoints. Conversely, if it is logically False , the axis is in steady state, allowing the controller to react to new setpoints.

Figure 2

ParMovAbs → MaxSpdSetPnt - Maximum speed setpoint for absolute movement, -REAL-

This input sets the maximum allowable speed of the linear axis during the movement in mode 1. It is defined in the same unit as the TgtPos input, per second. This parameter ensures that the linear axis moves at a controlled speed while reaching the target position defined by TgtPos . This sets the top speed for the linear axis during movement.

Figure 3

ParMovAbs → MaxAccSetPnt - Maximum acceleration for absolute movement, -REAL-

This input determines the maximum allowable acceleration of the linear axis during the movement. It is measured in the same unit as TgtPos per second squared. This parameter needs to be customized based on the specific system requirements. MaxAccSetPnt plays a critical role in regulating the acceleration of the linear axis as it follows the trajectory towards the target position. See Figure 3

ParMovAbs → JerkSetPnt - Jerk setpoint for absolute movement, -REAL-

JerkSetPnt controls the abruptness or smoothness of motion by regulating the rate of change of acceleration. It is measured in the same unit as TgtPos per second cubed. Adjusting JerkSetPnt allows users to customize the motion profile according to their desired level of abruptness or smoothness. For example, if the maximum acceleration needs to be achieved within half a second, the JerkSetPnt value should be set to double the maximum acceleration value.
Figure 4

Setting a jerk value as a setpoint is important for controlling the smoothness of acceleration and deceleration transitions. By managing the rate at which acceleration changes, users can prevent sudden, harsh movements that could cause mechanical wear or instability in the system. This ensures a smoother and more controlled operation, which is especially beneficial in applications where precision and mechanical longevity are critical.

ParMovRel
	Distance
	MaxSpdSetPnt
	MaxAccSetPnt
	JerkSetPnt

ParMovRel → Distance - Distance for the relative movement, -REAL-

The Distance input defines the distance the linear axis should move in relative movement mode, similar to the TgtPos input of the struct ParMovAbs in absolute movement mode, but with the key difference that it specifies the relative distance to be traveled rather than an absolute position. A positive value causes forward movement, while a negative value results in backward movement. The motion is initiated when a rising edge is detected on the ExeMov input. It is important to note that any changes to the parameters set by Distance during the motion will not be processed by the function until the current movement is completed. To operate the function in relative move Mode, the Mode input must be configured with a value of 2. This setting ensures that the function interprets the Distance input as the setpoint.
Figure 5

ParMovRel → MaxSpdSetPnt - Maximum speed setpoint, -REAL-

This input sets the maximum allowable speed of the linear axis during the movement in mode 2. It is defined in the same unit as the Distance input, per second. This parameter ensures that the linear axis moves at a controlled speed. This sets the top speed for the linear axis during movement.

ParMovRel → MaxAccSetPnt - Maximum acceleration setpoint, -REAL-

This input determines the maximum allowable acceleration of the linear axis during the movement in mode 2. It is measured in the same unit as Distance per second squared. This parameter needs to be customized based on the specific system requirements. MaxAccSetPnt plays a critical role in regulating the acceleration of the linear axis as it follows the trajectory towards the target position.

ParMovRel → JerkSetPnt - Jerk Setpoint for Relative Movement, -REAL-

JerkSetPnt controls the abruptness or smoothness of motion by regulating the rate of change of acceleration in mode 2. It is measured in the same unit as Distance per second cubed. Adjusting JerkSetPnt allows users to customize the motion profile according to their desired level of abruptness or smoothness. For example, if the maximum acceleration needs to be achieved within half a second, the JerkSetPnt value should be set to double the maximum acceleration value.

ParJog
	TgtSpd
	MaxAccSetPnt
	JerkSetPnt
	EnbPosCtrl

ParJog → TgtSpd - Target speed setpoint,-REAL-

When the Mode input is set to 3, the function operates in Jog Mode. In this mode, the linear axis moves forward with the configured speed, acceleration, and jerk as long as the JogFw input is True . If the JogBw input is activated, the linear axis moves backward. When JogFw and JogBw is set to False , the linear axis decelerates to a stop using the configured acceleration and jerk. This input defines the speed at which the linear axis moves while the JogFw or JogBw input is True , ensuring precise control over the jogging speed during manual operation.
Figure 6

ParJog → MaxAccSetPnt - Maximum Acceleration setpoint for jog mode,-REAL-

This input determines the maximum allowable acceleration of the linear axis during the movement in Jog Mode. It is measured in the same unit as Actual Position (ActPos) per second squared.

ParJog → JerkSetPnt - Jerk setpoint for jog mode,-REAL-

JerkSetPnt controls the abruptness or smoothness of motion in Jog Mode by regulating the rate of change of acceleration. It is measured in the same unit as actual position (ActPos) per second cubed. Adjusting JerkSetPnt allows users to customize the motion profile according to their desired level of abruptness or smoothness. Setting a jerk value as a setpoint is important for controlling the smoothness of acceleration and deceleration transitions. By managing the rate at which acceleration changes, users can prevent sudden, harsh movements that could cause mechanical wear or instability in the system. This ensures a smoother and more controlled operation, which is especially beneficial in applications where precision and mechanical longevity are critical.

ParJog → EnbPosCtrl - Enable position controller, -BOOL-

This input allows the user to enable or disable closed-loop position control in Jog Mode. When this input is set to true, the linear axis operates in closed-loop control, meaning that the position feedback is actively used to maintain accurate position control during jogging operations. If this input is set to false, the linear axis operates in feedforward mode only, with no position feedback control, relying solely on the predefined speed and acceleration settings. This provides flexibility depending on whether precise position control or simple open-loop control is required during Jog Mode.

ParSpdCtrl
	TgtSpd
	MaxAccSetPnt
	JerkSetPnt

ParSpdCtrl → TgtSpd - Target of speed control mode, -REAL-

The TgtSpd input is used to specify the target speed when the function block is configured in Motor Speed Mode. In this mode, the user can send a speed setpoint to the motor, which is executed with the configured acceleration and jerk parameters. The function generates and sends a motor speed setpoint independently of the linear axis’s position, allowing direct control of the motor’s rotational speed.

Whether you’re managing conveyors, pumps, fans, or other motion-driven applications, MotionProX ensures smooth, safe, and accurate motor speed transitions, protecting both your motor and mechanical components from excessive stress.

The unit for this input must be in a rotational speed format, such as RPM (revolutions per minute), rad/s (radians per second), or as a percentage of the motor’s nominal speed. This input provides precise control over the motor’s speed, making it ideal for applications where maintaining a specific motor speed is critical, regardless of the linear axis position.

In Motor Speed Mode, the user can change the target speed at any time. Any change to the TgtSpd input is immediately recognized by the function and is implemented using the configured acceleration and jerk parameters. This allows for real-time adjustments to the motor speed, ensuring responsive and precise control in dynamic applications.
Figure 7

ParSpdCtrl → MaxAccSetPnt - Maximum Motor Acceleration/Deceleration, -REAL-

input defines the maximum motor acceleration when the function block is operating in Motor Speed Mode. The unit for this input can be rpm/s, rad/s², or as a percentage of the motor’s nominal speed per second. This input controls the rate at which the motor can increase or decrease its speed, ensuring that acceleration/deceleration remains within safe and desired limits.

Please note that changes to this input are only possible when the motor is running at a constant speed. During the transition from one target speed (TgtSpd) to another, any changes to the MaxAccSetPnt input will not be processed by the function.

ParSpdCtrl → JerkSetPnt - Maximum MotorJerk, -REAL-

This input defines the jerk of the motor during speed changes in Motor Speed Mode. Jerk is the rate of change of acceleration or deceleration and is measured in units such as rpm/s^2, rad/s^3. It represents how quickly the motor’s acceleration increases or decreases over time.

ParStop
	DecSetPnt

ParStop → DecSetPnt - deceleration of the motor stop, -REAL-

The function block includes a stop feature that allows the motor to be halted immediately, regardless of the current Mode. As soon as a rising edge is detected on the Stop input, the function triggers a stop ramp to bring the motor to zero speed. The deceleration during this stop is defined by the DecSetPnt input, which can be configured in units such as [rpm/s], [rad/s²], or as a percentage of the nominal speed per second. After the stop input is activated, normal operation of the function can only resume once the Ack input is activated. This ensures that the system is properly reset and ready for continued use after an emergency or controlled stop.
Figure 8

CtrlPar
	Kp
	Ki
	GainFwdSpdCtrl
	GainBwdSpdCtrl
	ModeIntCtrl
	Window
	TuneTime

CtrlPar → Kp - Controller P-Factor, -REAL-

It represents the amplification factor of the P-controller within the position controller. A higher Kp value can enhance control accuracy. However, caution is advised: setting the Kp value excessively high may render the closed-loop system unstable. For optimal results and to maintain system stability, it is recommended to initiate with a modest Kp value and incrementally adjust upwards to achieve the desired precision. See example 2 for optimal adjustment.

CtrlPar → Ki - Controller I-Factor, -REAL-

Ki stands for the integration factor of the I-controller within the position controller. A Ki value set to zero effectively deactivates the I-controller. While a higher Ki value results in swifter error integration, enhancing overall accuracy, it can also introduce increased oscillations in the closed-loop system. For best performance, it is advisable to commence with a low Ki value and gradually increase it until the desired accuracy level is reached, balancing precision with system stability. See example 2 for optimal adjustment.

CtrlPar → GainFwdSpdCtrl - Positive speed feedforward, -REAL-

GainFwdSpdCtrl is a system parameter that adds a constant value for positive velocities to the control signal, improving trajectory tracking. It reduces the error signal and facilitates smoother following of the desired trajectory. The optimal positive feedforward value depends on the hardware and system dynamics, which can be determined through measurement and analysis, as illustrated in example 2.

CtrlPar → GainBwdSpdCtrl - Negative speed feedforward, -REAL-

GainBwdSpdCtrl is a system parameter that adds a constant value for negative velocities to the control signal, improving trajectory tracking. It reduces the error signal and facilitates smoother following of the desired trajectory. The optimal positive feedforward value depends on the hardware and system dynamics, which can be determined through measurement and analysis, as illustrated in example 2.

CtrlPar → ModeIntCntrl - Mode selection for internal integral controller, -BOOL-

This input determines the behavior of the I-Controller. When set to False , the I-Controller remains continuously active. If set to True , the I-Controller operates only in the steady state, deactivating during the linear axis movement. We advise setting this input to True , as allowing the I-Controller to function solely in the steady state often provides superior stability and accuracy for linear axes. This approach typically minimizes, if not eliminates, significant overshoots and, by enabling an increase in the Ki factor, greatly enhances accuracy.

CtrlPar → Window - Tolerance window of the target position, -REAL-

The Window input is used to define a positional tolerance band around the target position TgtPos of the ParMovAbs structure. When the absolute distance of actual position ActPos of the linear axis from the target position is within half of the Window value and remains within this range for at least the specified TuneTime (which is configurable in seconds), the function block will send a speed setpoint of exactly 0.0 to the motor. This functionality is crucial for achieving precise positioning. It ensures that when the axis gets close enough to the target position, the motor is gently brought to a complete stop, preventing overshoot and ensuring the axis remains within the desired positional accuracy. In figure 9 you can differentiate between three states:

Window and Positioning: As the actual position (black line) approaches the target position (red dashed line), the difference between them becomes smaller than half of the Window value (illustrated by the blue dashed lines).
TuneTime Activation: Once the actual position stays within this Window range for a duration of at least TuneTime (e.g. 0.5 seconds, as indicated on the graph), the function block signals the motor to reduce speed to exactly 0.0 (as shown in the CtrlOut graph).
Final Positioning: This results in the motor coming to a smooth and controlled stop.

This feature is essential for applications requiring high positional accuracy, as it prevents oscillations around the target position and ensures a stable final position.

Figure 9: Behaviour of the tolerance window and tune time.

CtrlPar → TuneTime - Amount of time in tolerance window, -REAL-

The TuneTime input specifies the minimum amount of time that the actual position ActPos must remain within the defined Window around the target position TgtPos before the function block sends a zero-speed setpoint to the motor. This time parameter is configurable in seconds.

The purpose of the TuneTime input is to ensure that the axis has settled within the acceptable positional tolerance before bringing the motor to a complete stop. By requiring the position to stay within the Window for a specified duration, TuneTime helps to prevent premature stopping due to transient conditions or small oscillations. This results in more stable and precise final positioning, reducing the likelihood of overshoot or drift after the motor has stopped. See figure 9

Enb - Turn controller on or off, -BOOL-

This input controls the activation or deactivation of the function. When the input signal is turned off False ,the function no longer responds to changes in the setpoints and does not generate any trajectory. The monitoring signal PosTrj reflects the current position, while the other monitoring signals SpdTrj and AccTrj are set to zero.
when the function is deactivated, the CtrlOut is set to zero, indicating that there is no movement caused by the controller, as shown in table 2.

	CtrlOut	PosTrj	SpdTrj	AccTrj
Enb = True	ccalculated based onthe position controlalgorithm	calculated by position trajectory generator	calculated by speed trajectory generator	calculated by acceleration trajectory generator
Enb = False	0.0	reflects current position ActPos	0.0	0.0

Table 2: Behavior of the output signals depending on the Enb input

Mode - Operation Mode Selection, -INT-

The function offers four different modes, as seen in table 3, which can be selected using the Mode input:

Mode = 1: In this mode, the function block operates as an absolute movement position controller. The active set of parameters is ParMovAbs The user can define a target position, and upon detecting a rising edge on the ExeMov input, the linear axis moves to this target position.
Mode = 2: In this mode, the function block acts as a relative movement position controller. The active parameter set is ParMovRel . The user can define a distance to move relative to the current position. When a rising edge is detected on the ExeMov input, the linear axis moves by the specified distance.
Mode = 3: This mode enables manual jog movements. The active parameter set is ParJog . In this mode, the user can execute manual movements using two boolean inputs, JogFw for forward movement and JogBw for backward movement. The linear axis moves forward or backward according to the ParJog parameters as long as one of these inputs is active.
Mode = 4: In this mode, the function block is configured to send a rotational speed setpoint to the motor. The active parameter set is ParSpdCtrl . The user can send a specific rotational speed setpoint with configurable acceleration and jerk to the motor. In this mode, the motor rotational speed is controlled independently of the linear axis position.

	1	2	3	4
Mode	Absolute movement position control	Relative movement position control	Jog Movement with Push Button	Motor Speed Control

Table 3: Different operation modes of the MotionProX function bock

ActPos - Actual position, -REAL-

This input represents the current measured position of the linear axis. It is used in the error signal calculation of the position controller. It should be provided in the same unit as TgtPos or Distance dependend of the selected mode.

ExeMov - Execution of the Movement, -BOOL-

The ExeMov input is used to initiate movement in either Mode 1 (absolute position control) or Mode 2 (relative position control). When a rising edge is detected on this input, the function block starts the movement based on the current mode settings. In Mode 1, the linear axis begins moving toward the specified target position, while in Mode 2, it moves by the defined relative distance. This input effectively serves as the start command for executing the programmed motion. See figure 4 and figure 5

JogFw - Input for forward movement in jog mode, -BOOL-

In Mode 4, the JogFw input controls the forward movement of the linear axis. As long as this input is active True , the axis moves forward according to the parameters defined in ParJog . When the JogFw input is deactivated (switches from True to False ), the function stops the linear axis using the same parameters, ensuring a smooth and controlled stop. This input is essential for manual jogging operations, allowing the user to control forward movement with precision. See figure 6

JogBw - Input for backward movement in jog mode, -BOOL-

The JogBw input controls the backward movement of the linear axis in Mode 4. When this input is active True , the axis moves backward according to the parameters defined in ParJog . If the JogBw input is deactivated (switches from True to False ), the function stops the linear axis using the same parameters, ensuring a smooth and controlled stop. This input is crucial for manual jogging operations, providing precise control over backward movement. See figure 6

Stop - Safety stop, -BOOL-

The Stop input is a critical safety and control feature that overrides all other modes of operation. Regardless of the current mode the function block is in, when a rising edge is detected on the Stop input, the function immediately sends a zero-speed setpoint to the motor. This command is executed with a configurable deceleration rate, ensuring the motor comes to a controlled and safe stop. This input is essential for emergency stops or situations where an immediate halt of the motor is required, providing a reliable way to quickly bring the system to a stop.

Figure 10

Ack - Acknowledge , -BOOL-

The Ack input is used to reset the function block after a stop command has been executed via the Stop input. Once the motor has been stopped, the function block is locked, preventing any further operations until a rising edge is detected on the Ack input. This input serves as a safety feature, ensuring that the system cannot resume normal operation until the stop event has been acknowledged by the user. It allows the user to verify and confirm that the system is ready to continue, ensuring controlled and safe operation after a stop condition.

Output Description

CtrlOut - Control Signal, -REAL-

The CtrlOut output is the main output of the function block, responsible for providing the motor speed setpoint. This output ensures that the linear axis reaches the desired position, or the motor achieves the target motor speed, or safely stops the motor, depending on the selected mode. The unit of this output, could be defined in rpm, rad/s, or a percentage of the motor’s nominal speed.

The CtrlOut signal must be connected to a motor speed controller, such as a frequency drive, which translates the setpoint into the actual motor speed. CtrlOut is essential for translating the function block’s control commands into motor speed, making it a crucial link between the control system and the motor drive.

PosTrj - Position trajectory, -REAL-

The PosTrj output displays the position trajectory of the linear axis as it moves toward the target position in Mode 1 or along the specified distance in Mode 2. When the function block is deactivated by setting Enb to False , is in Mode 4, or during the stop function, this output shows the current position of the linear axis. The unit of PosTrj is the same as that used for TgtPos or Distance dependend on the current Mode . This output is intended solely for display purposes and should not be used to control other functions, as its reliability for such purposes is not guaranteed by Halow-Tech. It provides a visual representation of the expected or current position of the axis, aiding in monitoring the system’s operation. See figure 2, figure 5 or figure 6

SpdTrj - Speed trajectory, -REAL-

The SpdTrj output displays the speed trajectory of the linear axis as it moves toward the target position in Mode 1, over the specified distance in Mode 2, or during jogging in Mode 3. In these modes, it represents the speed of the linear axis and shares the same unit as MaxSpdSetPnt or TgtSpd depending on the current Mode . In Mode 4, or when the function is deactivated, this output will be zero. The SpdTrj output is intended solely for display purposes and should not be used to control other functions, as its reliability for such use is not guaranteed by Halow-Tech. It provides a visual representation of the expected speed of linear axis, aiding in the monitoring and analysis of system performance. See figure 3, figure 4 or figure 6.

AccTrj - Acceleration trajectory,-REAL-

The AccTrj output represents the acceleration setpoint of the linear axis as it moves toward the target position in Mode 1, over the specified distance in Mode 2, or during jogging in Mode 3. In these modes, it reflects the linear acceleration and uses the same unit as MaxAccSetPnt . The AccTrj output is intended solely for display purposes and should not be used to control other functions, as its reliability for such use is not guaranteed by Halow-Tech. It provides a visual representation of the expected speed of linear axis, aiding in the monitoring and analysis of system performance. See figure 3, figure 4

Busy - Busy signal, -BOOL-

The Busy output indicates whether the internal trajectory generator is currently moving toward a target position. While the trajectory is in progress and the axis is moving to the new target, this output will be True . Once the target position is reached, the Busy output switches to False.While Busy is True , the function block does not respond to new setpoints or impulses at the ExeMov input, preventing any interruptions or changes during the ongoing motion. However, in Mode 3 (Jog Mode) and 4 (Speed Control Mode), the Busy output is always False . This means the user can adjust the TgtSpd in Mode 4 or use the push buttons in Mode 3 at any time, and the function block will immediately respond to these changes. This functionality ensures that the system can be dynamically controlled in these modes without waiting for the completion of a previous motion.
Figure 11

Done - Done signal, -BOOL-

The Done output indicates whether the positioning task has been completed. In Modes 1, 2, or 3, as long as the function block is sending a non-zero speed setpoint to the motor, this output will be False , meaning the positioning task is still in progress. Once the positioning task is complete, the Done output switches to True , indicating that the function block is now sending a speed setpoint of exactly 0.0 to the motor. This output is useful for signaling when the movement is fully completed, allowing the user or the control system to know when it is safe to proceed with the next operation or to issue new commands. It helps ensure that the motor has come to a full stop at the desired position before any further actions are taken. See figure 11

Error - Error conditions of the function block, -Boolean Array of 2 Elements-

The Error output is a boolean array with 5 elements, each indicating a specific error condition that prevents the function block from executing certain operations. Understanding these elements is crucial for diagnosing issues and ensuring the function block operates correctly. This output is essential for monitoring the status of the function block and ensuring safe operation. By check[1]ing these elements, users can quickly identify which mode or parameter is causing an issue, allowing them to correct the problem before attempting to execute new movements or speed commands. This ensures that the system operates. For an overview, see table 3.

Element 1, Mode 1 Error: If True , no new movement can occur in Mode 1. This indicates that one or more of the inputs MaxSpdSetPnt , MaxAccSetPnt or JerkSetPnt of the struct ParMovAbs are zero or negative.
Element 2, Mode 2 Error: If True , no new movement can occur in Mode 2. This indicates that one or more of the inputs MaxSpdSetPnt , MaxAccSetPnt or JerkSetPnt of the struct ParMovRel are zero or negative.
Element 3, Mode 3 Error: If True , no new movement can occur in Mode 3. This indicates that one or both of the inputs MaxAccSetPnt or JerkSetPnt of the struct ParJog are zero or negative. • Element 4, Mode 4 Error: If True , no new rotational speed setpoint can be issued in Mode 4. This indicates that one or both of the inputs MaxAccSetPnt or JerkSetPnt of the struct ParSpdCtrl are zero or negative.
Element 5, Stop condition Error: If True , no new movement or speed setpoint can be issued. This element remains True if the stop function has been activated and will only reset when the function’s main output CtrlOut is zero and the Ack input has been activated.

Figure 12

	Firs Element=True	Second element=True	third element=True	Forth element=True	Fifth element=True
Error	Invalid parameters ParMovAbs	Invalid parameters ParMovRel	Invalid parameters ParJog	Invalid parameters ParSpdCtrl	Not Acknowledged after Stop

Table 4: The different error codes of the FlexiMotion function block

Frequently Asked Questions (FAQ)

Can I change the target position while the linear axis is moving in Mode 1 or 2?

The function block will not respond to any setpint changes during the movement and will continue to move toward the original target. The function block only reacts to the new setpoints when the Busy output is False .

When can I change the mode?

The mode will be changed, when the Busy output is False (in Mode 1 or 2), when the motor speed is zero in Mode 4, or when the Done output is True in Mode 3.

What happens if I set the Enb input to False while the linear axis is moving or the motor speed is not zero?

If you deactivate the function block by setting the Enb input to False while the linear axis is in motion or the motor is running at a non-zero speed, the main output of the block will abruptly drop to zero. This sudden change in motor speed can potentially damage the motor or other mechanical components. Therefore, it’s important to ensure that the motor has come to a stop or the movement is complete before deactivating the block.

Tuning Motor Drive Parameters

In this examples, we’ll walk you through the steps to configure the technology block for accurate positioning of an electric axis. This step is essential before proceeding to the next steps, where you’ll tune the control parameters of the position controller.

The Technology Block calculates the motor’s rotational speed setpoint, which is output through CtrlOut . This output needs to be connected to a Frequency Drive that controls the motor’s speed. To ensure precise positioning, it’s crucial that the motor can accurately follow the rotational speed setpoint provided by CtrlOut . To achieve this, start by operating the Technology Block in Mode 4. In this mode, you’ll send rotational speed setpoints along with predefined acceleration and jerk values to the frequency drive.

The first step, described in this example, is to fine-tune the frequency drive’s control parameters so that the motor can quickly and accurately match the rotational speed setpoint, with minimal overshoot. The motor must also be capable of following these speed setpoints at the maximum allowable acceleration and jerk rates, maintaining precision and stability.

Once you’ve ensured that the motor’s speed control is highly responsive and stable, you can proceed to use the Technology Block in Modes 1, 2, and 3 for precise positioning tasks. This initial setup is key to achieving the accurate positioning required in these modes.

Important Safety Note for Operating in Mode 4: When operating the Technology Block in Mode 4, it’s crucial to pay close attention to the position of the linear axis. In Mode 4, rotational speed setpoints are sent to the motor regardless of the position of the linear axis. This means the motor will follow the speed commands without considering the current position, which can lead to unintended movements of the axis. To avoid any potential issues, it’s recommended to perform this step while the linear axis is not yet coupled to the motor, allowing the motor to spin freely without affecting the axis. This precaution helps prevent any accidental damage to the mechanical components or misalignment of the system. If this step is not carefully managed, the motor could drive the axis unexpectedly, leading to possible mechanical damage or even safety hazards.

The following is an example of the problems that can arise when setting the frequency Drive. At the end of the example, it is shown how precisely the entire system must react in order to use the controller.

Large Lag Error, No Steady-State Accuracy

The issue of motor speed control in Figure 13 includes two main problems: (a) Large Lag Error: The actual motor speed (blue line) lags significantly behind the motor speed set trajectory (black line), indicating poor tracking performance. The motor takes too long to reach the desired speed, resulting in a slow response. (b) No Steady-State Accuracy: The actual motor speed never reaches or maintains the target speed (red dashed line).

Figure 13

Large Lag Error, Overshoot and Oscillation

The issue in Figure 14 includes two main problems: (a) Large Lag Error: The actual motor speed (blue line) significantly lags behind the set trajectory (black line) during both the acceleration and deceleration phases, indicating a delayed response in following the desired speed profile. (b) Overshoot and Oscillation: After reaching the target speed, the actual motor speed overshoots the setpoint (red dashed line) and exhibits oscillations, indicating poor damping and instability in the speed control, leading to oscillatory behavior instead of smooth convergence to the target speed.

Figure 14

Large Lag Error

The behavior in Figure 15 is better than in both Figures 13 and 14, but there remains an issue: (a) Large Lag Error, where the actual motor speed (blue line) still lags behind the set trajectory (black line) during acceleration and deceleration phases, indicating that the response is still delayed in following the desired speed profile.

Figure 15

Relatively large Lag Error

The behavior in the Figure 16 is an improvement compared to the previous figures, but there is still a relatively large Lag Error: The actual motor speed (blue line) continues to lag behind the set trajectory (black line), indicating a delayed response in following the desired speed profile. While performance has improved, the motor still struggles to match the speed changes accurately.

Figure 16

Optimal Behaviour

Optimal set of controller parameters in figure 17: The lag error between set trajectory (black line) and motor actual speed (the blue line) is negligibly small, there is no over shoot and no oscillation. steady- state accuracy is very high.

Figure 17

How to Configure MotionProX Control Parameters

This guide provides detailed instructions on how to set up and configure the Technology Block MotionProX for precise positioning tasks of an electric linear axis. To proceed with the following steps, the motor frequency drive must be configured as described in the previous section. This setup is a prerequisite for successful tuning of the position control parameters.

Important for all examples: The values of control parameters provided in the following sections are solely as examples to illustrate the approach for setting control parameters. Under no circumstances should these values be directly applied to your machine, not even as initial starting points. The control parameters must be explicitly adjusted for each machine individually.

1. General Informations

Cyclic Interrupt task Setup: Ensure that the Technology Block is called within a cyclic interrupt task in your PLC. The feedback for the actual position must be read at least as frequently as the cycle time of the this cyclic interrupt task.
Sampling Time: The task cycle time should be relatively fast, depending on the required accuracy and motor dynamics. A sampling time of 1 to 5 milliseconds is a good starting point.
Communication with the Frequency Drive: The Technology Block only calculates the speed setpoint for the frequency drive. Control and status words for communication with the drive must be programmed separately by the user. The speed setpoint calculated at the CtrlOut output should be sent directly to the frequency drive without modification.

2. Define Units

Consistency in Units: Before configuring the block, decide on the units you will use for the system. These units must remain consistent throughout the configuration. For example, if you choose millimeters for the linear axis, then all related variables should be in millimeters: Actual Position [mm], Target Position [mm], Speed Setpoint [ mm/s ], Acceleration Setpoint [ mm/s 2 ], and Jerk [ mm/s 3 ]. For motor parameters, you might use rpm: Motor Target Speed [rpm], Motor Acceleration [ rpm/s ], Motor Jerk [ rpm/s 2 ].
Other Unit Options: You can choose other units, such as meters, centimeters, micrometers for the linear axis, or rad/s or percentage of nominal motor speed for the motor. The key is to select a unit system and maintain consistency across all parameters and modes.

3. Set General Parameters

Sample Time: Enter the PLC’s task cycle time (in seconds) into the SampleTime input.
Max and Min Output: Define the maximum and minimum speed the Technology Block can output using MaxOut and MinOut , for example, 1500 rpm maximum and −1500 rpm minimum.

4. Select this Mode for Tuning the Control Prameters

Switch the block to Mode 1. Using the setpoint structure ParMovAbs , define a target position with corresponding speed, acceleration, and jerk setpoints. Ensure that all setpoints (speed,acceleration, jerk) are greater than zero.

5. Set Kp and Target Accuracy

Kp Setting: Initially, enter a small value for Kp of the CtrlPar structure.
Define Accuracy Window: Set the accuracy window using Window input in the same units chosen for the linear axis (e.g., 0.2mm).
Tune Time: Enter a value in seconds for TuneTime (e.g., 0.3s).
Other Control Parameters: You can leave other control parameters at zero for now; they will be adjusted later

6. Activate the Fucntion and Execute Movement

Block Activation: Activate the block by setting Enb to True . Trigger a movement by sending a pulse to the ExeMov ‘ input and observe the linear axis movement.
The goal at this stage is to ensure that the actual position and the generated position trajectory (PosTrj output) are parallel. Do not focus on target accuracy at this point. See figure 18.

Figure 18: Example with Kp too small! (Kp = 10, Window = 0.2mm, TuneTime = 0.3s)

7. Kp Tuning

Incremental Kp Adjustments: Gradually increase the Kp value. After each increment, execute a new movement by defining an appropriate target position and sending a pulse to ExeMov .
Objective: Continue this process until the position trajectory (PosTrj ) and the actual position are parallel, indicating proper tuning. see figures 19, 20 and 21.

Figure 19: Kp increased to 20, still small! (Kp = 20, Ki = 0.0, GainFwdSpdCtrl = 0.0, GainBwdSpdCtrl = 0.0, Window = 0.2mm, TuneTime = 0.3s)

Figure 20: Kp increased to 50, still small! (Kp = 50, Ki = 0.0, GainFwdSpdCtrl = 0.0, GainBwdSpdCtrl = 0.0,Window=0.2mm, TuneTime = 0.3s))

Figure 21: Kp increased to 200, ready for next step! (Kp = 200, Ki = 0.0, GainFwdSpdCtrl = 0.0, GainBwdSpdCtrl = 0.0,Window = 0.2mm, TuneTime = 0.3s)

8. Determine the Positive Feedforward Parameter

Execute a Positive Movement: Run a positive movement of the linear axis.
Measure Motor Speed: At a point where the actual position and the position trajectory (PosTrj ) are parallel, read the motor speed.
Calculate GainFwdSpdCtrl: Divide the motor speed by the set speed value (MaxSpdSetPnt of the structure ParMovAbs ). The result is the value you should enter into GainFwdSpdCtrl of the structure CtrlPar . In thhe example shown in figure 20. The MaxSpdSetPnt was set to 5 [mm/]s. The motor speed is 520.52rpm(see figure 21). The value for GainFwdSpdCtrl is then calculated by: GainFwdSpdCtrl => 520.52/5= 104.1

Figure 22: Adjusted Feedfordward parameters (Kp = 200, Ki = 0.0, GainFwdSpdCtrl = 104.1, GainBwdSpdCtrl = 0.0, Window = 0.2mm, TuneTime = 0.3s)

9. Determine the Negative Feedforward Parameter

Repeat Step 8: Perform the same process as in Step 8, but with a negative movement of the linear axis.
Calculate and Set Gain: Write the resulting value into GainBwdSpdCtrl of the strucutre CtrlPar .

10. Fine-Tune Feedforward Parameters (Optional)

Execute a Movement: Run a movement using the Kp = 20 value and the determined feedforward parameters.
Analyze the Motion: The movement should resemble the ideal trajectory shown in reference images (e.g., similar to figure 19).
Refine GainFwdSpdCtrl : Determine the positive feedforward gain again by observing the highest motor speed during the movement. Divide this by the set speed value (MaxSpdSetPnt ) and update GainFwd[1]SpdCtrl with this value. See figure 20. GainFwdSpdCtrl = 553.88 / 5 = 110.7
Refine GainBwdSpdCtrl : Repeat the process with a negative movement to refine GainBwdSpdCtrl .

Figure 23: (Kp = 200, Ki = 0.0, GainFwdSpdCtrl = 104.1, GainBwdSpdCtrl = 110.7, Window = 0.2mm, TuneTime = 0.3s)

11. Adjust Ki Parameter

Monitor Signals: Observe the time between when the Busy signal is reset and when the Done signal is set.
Increase Ki : Gradually increase the Ki value and minimize the TuneTime to achieve the desired speed and responsiveness.

12. Finalize the Position Controller Setup

Optimal Configuration: Once the Kp , feedforward parameters, and Ki are tuned, the position controller is optimally set.
Run Movements in Modes 1, 2, and 3: You can now move the linear axis in Modes 1, 2, and 3 with any target positions, speeds, accelerations, and jerks that your mechanics and motor can handle, without needing to adjust the CtrlPar values again.
By following these steps, you ensure that your Technology Block is finely tuned for accurate and responsive control, enabling smooth and precise operation of the electric axis in various modes.

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