Complete Guide to Mitsubishi FX5U PLC Pulse Axis Control: From Wiring to ST Programming

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Precise control, efficient motion – creating an intelligent servo control system

In the field of industrial automation, servo motor control is one of the core technologies. Today, we will delve into how to use the Mitsubishi FX5U PLC to write a complete pulse axis control program using ST language, including comprehensive functions such as enabling, homing, jogging, and positioning, while integrating a touchscreen human-machine interface for comprehensive monitoring and parameter settings.

1. Hardware Configuration and Wiring Diagram

IO Allocation Table

Signal Type	PLC Port	Function Description
Output Signal	Y0	Pulse Output
Output Signal	Y4	Direction Signal
Output Signal	Y10	Servo Enable Output
Input Signal	X0	Servo Ready
Input Signal	X1	Homing Signal
Input Signal	X2	Proximity Signal
Input Signal	X3	Positive Limit Signal
Input Signal	X4	Negative Limit Signal
Input Signal	X10	Servo Alarm
Input Signal	X11	Emergency Stop Signal (Normally Closed)

Complete Guide to Mitsubishi FX5U PLC Pulse Axis Control: From Wiring to ST Programming

2. Complete Implementation of ST Language Program (with Detailed Comments)

The following is the complete ST language program, including touchscreen interface variables, emergency stop handling, and comprehensive status monitoring:

// Mitsubishi FX5U Pulse Axis Control Program (using built-in motion control instructions) // Axis Configuration: using Y0 as pulse output, Y4 as direction signal, Y10 as servo enable // Input Signals: X0 - Servo Ready, X1 - Homing Signal, X2 - Proximity Signal, X3 - Positive Limit, X4 - Negative Limit, X10 - Servo Alarm, X11 - Emergency Stop Signal // Global Variable Definition VAR_GLOBAL    // Axis Status Variables (Touchscreen Monitoring)    Axis_Enabled: BOOL;           // Axis Enable Status    Axis_Error: BOOL;             // Axis Error Status    Axis_Busy: BOOL;              // Axis Busy Status    Axis_Home_Done: BOOL;         // Homing Completion Flag    Axis_Servo_Ready: BOOL;       // Servo Ready Status    Axis_Servo_Alarm: BOOL;       // Servo Alarm Status    Axis_Emergency_Stop: BOOL;    // Emergency Stop Status (Touchscreen Display)    Axis_Position: LREAL;         // Current Position (Touchscreen Display)    // Motion Parameters (Touchscreen Settings)    Axis_Target_Position: LREAL;  // Target Position (Touchscreen Settings)    Axis_Speed: LREAL := 50000.0; // Motion Speed (Touchscreen Settings)    Axis_Accel: LREAL := 100000.0;// Acceleration (Touchscreen Settings)    Axis_Decel: LREAL := 100000.0;// Deceleration (Touchscreen Settings)    // Jog Parameters (Touchscreen Settings)    Jog_Speed: LREAL := 20000.0;  // Jog Speed (Touchscreen Settings)    // Homing Parameters (Touchscreen Settings)    Home_Speed_Slow: LREAL := 5000.0;    // Homing Return Low Speed (Touchscreen Settings)    Home_Speed_Fast: LREAL := 30000.0;   // Homing Return High Speed (Touchscreen Settings)    Home_Offset: LREAL := 0.0;           // Homing Offset (Touchscreen Settings)    // Operation Commands (Touchscreen Control)    Cmd_Enable: BOOL;             // Enable Command (Touchscreen Button)    Cmd_Disable: BOOL;            // Disable Command (Touchscreen Button)    Cmd_Home: BOOL;               // Homing Command (Touchscreen Button)    Cmd_Jog_Forward: BOOL;        // Jog Forward (Touchscreen Button)    Cmd_Jog_Reverse: BOOL;        // Jog Reverse (Touchscreen Button)    Cmd_Move_Absolute: BOOL;      // Absolute Positioning Command (Touchscreen Button)    Cmd_Move_Relative: BOOL;      // Relative Positioning Command (Touchscreen Button)    Cmd_Stop: BOOL;               // Stop Command (Touchscreen Button)    Cmd_Reset: BOOL;              // Error Reset Command (Touchscreen Button)    // Motion Control Instruction Instances    MC_Power_0: MC_POWER;                 // Servo Enable Instruction    MC_Home_0: MC_HOME;                   // Homing Instruction    MC_Jog_0: MC_JOG;                     // Jog Instruction    MC_MoveAbsolute_0: MC_MOVEABSOLUTE;   // Absolute Positioning Instruction    MC_MoveRelative_0: MC_MOVERELATIVE;   // Relative Positioning Instruction    MC_Stop_0: MC_STOP;                   // Stop Instruction    MC_Reset_0: MC_RESET;                 // Error Reset Instruction    // Internal Use Variables    Execute_Home: BOOL;                   // Execute Homing    Execute_JogFwd: BOOL;                 // Execute Jog Forward    Execute_JogRev: BOOL;                 // Execute Jog Reverse    Execute_MoveAbs: BOOL;                // Execute Absolute Positioning    Execute_MoveRel: BOOL;                // Execute Relative Positioning    Execute_Stop: BOOL;                   // Execute Stop    Execute_Reset: BOOL;                  // Execute Reset    Last_Cmd_Home: BOOL;                  // Last Homing Command Status    Last_Cmd_JogFwd: BOOL;                // Last Jog Forward Command Status    Last_Cmd_JogRev: BOOL;                // Last Jog Reverse Command Status    Last_Cmd_MoveAbs: BOOL;               // Last Absolute Positioning Command Status    Last_Cmd_MoveRel: BOOL;               // Last Relative Positioning Command Status    Last_Cmd_Stop: BOOL;                  // Last Stop Command Status    Last_Cmd_Reset: BOOL;                 // Last Reset Command Status    Axis_No: INT := 1;                    // Axis Number (set according to actual configuration)    Error_Code: INT;                      // Error Code (Touchscreen Display)    Error_Message: STRING[50];            // Error Message (Touchscreen Display) END_VAR

Main Program

// Main Program PROGRAM MAIN VAR    // Local Temporary Variables    Temp_Bool: BOOL;    Temp_Error: BOOL; BEGIN    // ==================== Input Signal Reading and Status Update ====================    // Read Servo Status Signals    Axis_Servo_Ready := X0;       // Servo Ready Signal (X0 Input)    Axis_Servo_Alarm := X10;      // Servo Alarm Signal (X10 Input)    Axis_Emergency_Stop := NOT X11; // Emergency Stop Signal (X11 is Normally Closed, conducting under normal conditions, disconnecting during emergency)    // ==================== Emergency Stop Handling ====================    // Emergency stop signal has the highest priority, and should immediately stop motion in any case    IF Axis_Emergency_Stop THEN        // Execute Emergency Stop        MC_Stop_0(            Axis := Axis_No,             Execute := TRUE,             Done =&gt; Temp_Bool,             Busy =&gt; Temp_Bool,             Error =&gt; Temp_Error,             ErrorID =&gt; Error_Code        );        // Disable all motion commands        Execute_Home := FALSE;        Execute_JogFwd := FALSE;        Execute_JogRev := FALSE;        Execute_MoveAbs := FALSE;        Execute_MoveRel := FALSE;        // Reset all command flags        Cmd_Home := FALSE;        Cmd_Jog_Forward := FALSE;        Cmd_Jog_Reverse := FALSE;        Cmd_Move_Absolute := FALSE;        Cmd_Move_Relative := FALSE;        // Set error status        Axis_Error := TRUE;        Error_Message := "Emergency stop triggered!";        // Directly return, do not execute subsequent logic        RETURN;    END_IF;

Axis Enable/Disable Control/Error Reset

// ==================== Axis Enable/Disable Control ====================    // Enable axis control (only when servo is ready and no alarm)    IF Cmd_Enable AND NOT Axis_Enabled AND Axis_Servo_Ready AND NOT Axis_Servo_Alarm THEN        MC_Power_0(            Axis := Axis_No,             Enable := TRUE,             Enable_Positive := TRUE,             Enable_Negative := TRUE,             Status =&gt; Axis_Enabled,             Busy =&gt; Temp_Bool,             Error =&gt; Axis_Error,             ErrorID =&gt; Error_Code        );        Cmd_Enable := FALSE;  // Reset command flag    END_IF;    // Disable axis control    IF Cmd_Disable AND Axis_Enabled THEN        MC_Power_0(            Axis := Axis_No,             Enable := FALSE,             Status =&gt; Axis_Enabled,             Error =&gt; Axis_Error,             ErrorID =&gt; Error_Code        );        Cmd_Disable := FALSE;  // Reset command flag    END_IF;    // ==================== Error Reset Handling ====================    // Error reset command detection (rising edge triggered)    IF Cmd_Reset AND NOT Last_Cmd_Reset AND Axis_Error THEN        Execute_Reset := TRUE;    END_IF;    // Execute error reset    IF Execute_Reset THEN        MC_Reset_0(            Axis := Axis_No,             Execute := TRUE,             Done =&gt; Temp_Bool,             Busy =&gt; Temp_Bool,             Error =&gt; Temp_Error,             ErrorID =&gt; Error_Code        );        // Clear flags after reset completion        IF Temp_Bool THEN            Execute_Reset := FALSE;            Cmd_Reset := FALSE;            Axis_Error := FALSE;        END_IF;    END_IF;    // Save reset command status for next comparison    Last_Cmd_Reset := Cmd_Reset;

Homing Control

// ==================== Homing Control ====================    // Homing command detection (rising edge triggered)    IF Cmd_Home AND NOT Last_Cmd_Home AND Axis_Enabled AND NOT Axis_Error THEN        Execute_Home := TRUE;    END_IF;    // Execute homing operation    IF Execute_Home THEN        MC_Home_0(            Axis := Axis_No,             Execute := TRUE,             Position := Home_Offset,         // Homing Offset            BufferMode := 0,                 // Buffer Mode: 0 - Immediate Execution            Done =&gt; Axis_Home_Done,          // Homing Completion Flag            Busy =&gt; Axis_Busy,               // Axis Busy Status            CommandAborted =&gt; Temp_Bool,     // Command Aborted Flag            Error =&gt; Axis_Error,             // Error Status            ErrorID =&gt; Error_Code            // Error Code        );        // Clear execution flag when homing is complete or error occurs        IF Axis_Home_Done OR Axis_Error THEN            Execute_Home := FALSE;            Cmd_Home := FALSE;        END_IF;    END_IF;    // Save homing command status for next comparison    Last_Cmd_Home := Cmd_Home;

Jog Control

// ==================== Jog Control ====================    // Forward jog command detection (rising edge triggered)    IF Cmd_Jog_Forward AND NOT Last_Cmd_JogFwd AND Axis_Enabled AND NOT Axis_Error AND Axis_Home_Done THEN        Execute_JogFwd := TRUE;    END_IF;    // Reverse jog command detection (rising edge triggered)    IF Cmd_Jog_Reverse AND NOT Last_Cmd_JogRev AND Axis_Enabled AND NOT Axis_Error AND Axis_Home_Done THEN        Execute_JogRev := TRUE;    END_IF;    // Execute forward jog    IF Execute_JogFwd THEN        MC_Jog_0(            Axis := Axis_No,             JogForward := TRUE,             JogBackward := FALSE,             Velocity := Jog_Speed,           // Jog Speed            Acceleration := Axis_Accel,      // Acceleration            Deceleration := Axis_Decel,      // Deceleration            Busy =&gt; Axis_Busy,               // Axis Busy Status            Error =&gt; Axis_Error,             // Error Status            ErrorID =&gt; Error_Code            // Error Code        );        // Clear execution flag when jog command stops or error occurs        IF NOT Cmd_Jog_Forward OR Axis_Error THEN            Execute_JogFwd := FALSE;            Cmd_Jog_Forward := FALSE;        END_IF;    END_IF;    // Execute reverse jog    IF Execute_JogRev THEN        MC_Jog_0(            Axis := Axis_No,             JogForward := FALSE,             JogBackward := TRUE,             Velocity := Jog_Speed,           // Jog Speed            Acceleration := Axis_Accel,      // Acceleration            Deceleration := Axis_Decel,      // Deceleration            Busy =&gt; Axis_Busy,               // Axis Busy Status            Error =&gt; Axis_Error,             // Error Status            ErrorID =&gt; Error_Code            // Error Code        );        // Clear execution flag when jog command stops or error occurs        IF NOT Cmd_Jog_Reverse OR Axis_Error THEN            Execute_JogRev := FALSE;            Cmd_Jog_Reverse := FALSE;        END_IF;    END_IF;    // Save jog command status for next comparison    Last_Cmd_JogFwd := Cmd_Jog_Forward;    Last_Cmd_JogRev := Cmd_Jog_Reverse;

Absolute/Relative Positioning Control

    // ==================== Absolute Positioning Control ====================    // Absolute positioning command detection (rising edge triggered)    IF Cmd_Move_Absolute AND NOT Last_Cmd_MoveAbs AND Axis_Enabled AND NOT Axis_Error AND Axis_Home_Done THEN        Execute_MoveAbs := TRUE;    END_IF;    // Execute absolute positioning    IF Execute_MoveAbs THEN        MC_MoveAbsolute_0(            Axis := Axis_No,             Execute := TRUE,             Position := Axis_Target_Position, // Target Position            Velocity := Axis_Speed,           // Motion Speed            Acceleration := Axis_Accel,       // Acceleration            Deceleration := Axis_Decel,       // Deceleration            Done =&gt; Temp_Bool,                // Positioning Completion Flag            Busy =&gt; Axis_Busy,                // Axis Busy Status            CommandAborted =&gt; Temp_Bool,      // Command Aborted Flag            Error =&gt; Axis_Error,              // Error Status            ErrorID =&gt; Error_Code             // Error Code        );        // Clear execution flag when positioning is complete or error occurs        IF NOT Axis_Busy OR Axis_Error THEN            Execute_MoveAbs := FALSE;            Cmd_Move_Absolute := FALSE;        END_IF;    END_IF;    // Save absolute positioning command status for next comparison    Last_Cmd_MoveAbs := Cmd_Move_Absolute;    // ==================== Relative Positioning Control ====================    // Relative positioning command detection (rising edge triggered)    IF Cmd_Move_Relative AND NOT Last_Cmd_MoveRel AND Axis_Enabled AND NOT Axis_Error AND Axis_Home_Done THEN        Execute_MoveRel := TRUE;    END_IF;    // Execute relative positioning    IF Execute_MoveRel THEN        MC_MoveRelative_0(            Axis := Axis_No,             Execute := TRUE,             Distance := Axis_Target_Position, // Move Distance            Velocity := Axis_Speed,           // Motion Speed            Acceleration := Axis_Accel,       // Acceleration            Deceleration := Axis_Decel,       // Deceleration            Done =&gt; Temp_Bool,                // Positioning Completion Flag            Busy =&gt; Axis_Busy,                // Axis Busy Status            CommandAborted =&gt; Temp_Bool,      // Command Aborted Flag            Error =&gt; Axis_Error,              // Error Status            ErrorID =&gt; Error_Code             // Error Code        );        // Clear execution flag when positioning is complete or error occurs        IF NOT Axis_Busy OR Axis_Error THEN            Execute_MoveRel := FALSE;            Cmd_Move_Relative := FALSE;        END_IF;    END_IF;    // Save relative positioning command status for next comparison    Last_Cmd_MoveRel := Cmd_Move_Relative;

Stop Control/Error Reset

    // ==================== Stop Control ====================    // Stop command detection (rising edge triggered)    IF Cmd_Stop AND NOT Last_Cmd_Stop AND (Axis_Busy OR Execute_JogFwd OR Execute_JogRev) THEN        Execute_Stop := TRUE;    END_IF;    // Execute stop operation    IF Execute_Stop THEN        MC_Stop_0(            Axis := Axis_No,             Execute := TRUE,             Done =&gt; Temp_Bool,             Busy =&gt; Temp_Bool,             Error =&gt; Axis_Error,             ErrorID =&gt; Error_Code        );        // Clear all motion execution flags        Execute_Stop := FALSE;        Execute_JogFwd := FALSE;        Execute_JogRev := FALSE;        Execute_MoveAbs := FALSE;        Execute_MoveRel := FALSE;        // Reset all motion command flags        Cmd_Stop := FALSE;        Cmd_Jog_Forward := FALSE;        Cmd_Jog_Reverse := FALSE;        Cmd_Move_Absolute := FALSE;        Cmd_Move_Relative := FALSE;    END_IF;    // Save stop command status for next comparison    Last_Cmd_Stop := Cmd_Stop;    // ==================== Position Feedback and Status Update ====================    // Get current position (needs to read the corresponding register based on actual configuration)    // Here it is assumed that the current position is stored in D8340 (32-bit), please adjust according to PLC configuration in actual use    Axis_Position := DINT_TO_LREAL(D8340);    // ==================== Error Information Handling ====================    // Generate error information based on error code    CASE Error_Code OF        0: Error_Message := "No Error";        16#1001: Error_Message := "Axis Not Enabled";        16#1002: Error_Message := "Axis Busy";        16#1003: Error_Message := "Command Execution Error";        16#1004: Error_Message := "Limit Switch Triggered";        16#1005: Error_Message := "Homing Return Error";        16#1006: Error_Message := "Servo Alarm";        16#1007: Error_Message := "Emergency Stop Triggered";        ELSE Error_Message := CONCAT("Unknown Error: ", INT_TO_STRING(Error_Code));    END_CASE;    // ==================== Output Control ====================    // Servo enable output control (only output when axis is enabled and no error)    Y10 := Axis_Enabled AND NOT Axis_Error; END_PROGRAM

3. Touchscreen Interface Design

The touchscreen monitoring interface should include the following areas:

Status Display Area:

Servo Enable Status Indicator
Servo Ready Status Indicator
Servo Alarm Status Indicator
Emergency Stop Status Indicator
Axis Busy Status Indicator
Homing Completion Status Indicator
Current Position Real-time Display
Error Code and Information Display

Parameter Setting Area:

Target Position Setting
Motion Speed Setting
Acceleration/Deceleration Setting
Jog Speed Setting
Homing Parameter Settings (High Speed, Low Speed, Offset)

Operation Control Area:

Servo Enable/Disable Button
Homing Button
Forward Jog/Reverse Jog Button
Absolute Positioning/Relative Positioning Button
Emergency Stop Button
Error Reset Button

4. System Functional Features

Comprehensive Status Monitoring:

Real-time display of various statuses of the servo system
Intuitive display of error codes and information
Real-time update of current position

Emergency Stop Safety Protection:

Highest priority handling of emergency stop signals
Immediate stop of all motion during emergency stop
Clear display of emergency stop status

Flexible Parameter Settings:

All motion parameters can be set via the touchscreen
Parameter range limits and validity checks
Parameter saving and calling functions

Safety Protection Mechanisms:

Limit switch protection
Servo alarm detection
Emergency stop function
Automatic error handling

User-friendly Interface:

Intuitive and clear status indicator lights
Reasonable layout of operation buttons
Simple and convenient parameter settings

5. Application Considerations

System Debugging:

Perform homing operation first during the first run
Gradually adjust motion parameters to optimal values
Test the functionality of each limit switch
Verify the reliability of the emergency stop function

Safety Matters:

Ensure the emergency stop function works properly
Set reasonable soft limit protection
Regularly check the connection status of the servo system
Emergency stop button should use normally closed contacts

Maintenance:

Regularly check the status of the servo drive
Keep backups of PLC and touchscreen programs
Record parameter settings and modification history
Regularly test the emergency stop function

Conclusion

This article provides a detailed introduction to a complete Mitsubishi FX5U PLC pulse axis control system, from hardware wiring to software programming, and touchscreen interface design, offering a comprehensive solution. This system features high stability, ease of operation, and comprehensive functionality, particularly enhancing the emergency stop safety protection feature, making it widely applicable in various industrial automation scenarios.

Through this system, users can easily achieve precise control of servo motors, improving equipment automation levels and production efficiency. We hope this article can provide valuable references for your automation projects.

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