Predefined homing methods

Homing modes are specialized functions used to align an axis with a known position. This is essential in applications where motion is restricted and there is no absolute position sensor.

This application note provides an overview of the predefined homing modes in Easy Motion Studio II and demonstrates how to home the axis to a limit switch using homing method 18 – “Homing to the Positive Limit Switch.”

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Custom homing modes implementation

This application note outlines the steps to implement a custom homing routine that positions the load at the center of the working area.

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Drive special inputs – Limit switches

This application note describes the default functionality of limit switch inputs and explains how to disable it to use the respective digital inputs as general-purpose inputs.

The document also details how to restrict load movement using the software limit switches option.

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Drive special inputs – ENABLE

The Enable input allows connecting an emergency signal that can come from the master or simply from an emergency button.

When the Enable input becomes “inactive”, the drive performs the following actions:

• deactivates the PWM outputs
• sets the bit 15 (“Enable is inactive”) in the MER (Motion Error Register) error register
• generates the “int0 – Enable input has changed” TML interrupt

Remark: With the PWM outputs being deactivated, the motor will not be energized anymore, so it will stop freely, becoming fully dependent on the load inertia and system friction.

When the Enable input changes back to “active”, the MER.15 bit is reset but the PWM outputs remain deactivated, with one exception: when the drive was executing an electronic gearing profile.

The “int0 – Enable input has changed” interrupt is triggered when the Enable input becomes active.

This application note presents an example on how to restore a predefined motion cycle (stored at the drive level), when the Enable input is reactivated.

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Motion start/stop using two digital inputs

This application note describes how to use two digital inputs (IN0 and IN1), to start/stop the motion profile.

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TML loop with motion profiles and events

This application note outlines the procedure for constructing a loop utilizing a label and the “GOTO” TML instruction. For illustrative purposes, this loop incorporates two motion profiles, each triggered by distinct time events.

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How to call a TML function from a master

This application note describes how to create a TML function with EasyMotion Studio II and call it from an RS232, a CANopen or an EtherCAT master.

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TML interrupt routines usage

This application note describes how to activate and customize the TML interrupt services routines, using an example that sets the “Int 10 – Time period has elapsed” interrupt, to flash a LED, connected to one of the drive digital outputs.

The TML interrupts are special conditions that are continuously monitored by the drive firmware. When a TML interrupt occurs, the main TML program execution is suspended and the TML code associated with the interrupt, called Interrupt Service Routine (in short ISR), is executed. While an interrupt is active (meaning the ISR code is being executed), all the TML interrupts are globally disabled.

That is why, it is recommended to put in the ISR (Interrupt Status Register) only the minimum needed code. If this is not possible, then other interrupts can be re-enabled using the “Interrupts Settings” dialogue (will be presented in chapter 3).

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Changing the current limit at runtime

This application note describes different methods of changing the current limit (in the case of the DC brushed and brushless motors and for the closed loop driving of stepper motors) and the run current (in the case of constant current drive used in open-loop stepper motors). These parameters may be changed during setup or at runtime through the command interpreter window or using a TML function (ex: Set 16-Bit Variable).

The current limit is a user-definable parameter representing the maximum allowed current reference used by the drive to control the motor. Considering its purpose, it should be set higher than the motor nominal current, to allow high dynamic movements, but slightly lower than the motor/drive peak current to prevent possible damage.

The run current represents the constant current value used to drive open-loop stepper motors. Its value is usually set equal to the motor’s nominal current.

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How to restore the operation after a fault

This application presents an example on how to restore the application operation after the drive enters a fault state. The idea behind the default operation of the drive is that in case of an error the user intervention is required (to determine the reason for the error and to take the corrective actions needed to prevent it from happening again).

Default behavior in case of an error:

• Switch off green LED
• Switch on red LED
• Disable the power stage by cutting the PWM outputs and suspend the controllers / trajectory generation
• Aborts any ongoing special calls / functions / homing and terminate the execution of the TML program.

Proposed recovery sequence:

• Switch off the green LED
• Switch on the red LED
• Cutoff drive PWM outputs
• Wait until the error condition disappears
• Program the motor to hold its current position
• Re-activate the drive PWM outputs
• Switch off the red LED and switch on the green LED
• Resume the main program and process the commands received from the master.

The application uses the software protection interrupt, which monitors the following software protections:

• Over current;
• Over temperature – drive (if available);
• Over temperature – motor (if available);
• I2t drive;
• I2t motor;
• Over voltage;
• Under voltage;
• Encoder broken wire (when incremental encoder is used and digital hall sensors are also present);

The easiest way to evaluate this application is to create an over-voltage condition thus having the drive enter the fault state. This can be done by decreasing the over-voltage protection threshold value under the supply voltage value. The parameter that stores the over voltage protection threshold value is called “UMAXPROT”. We can then notice the drive behaviour and by returning UMAXPROT to its initial value, we can see the actual error recovery taking place.

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