FB_CoEAX8000BrakeTest

FB_CoEAX8000BrakeTest 1:

The function block FB_CoEAX8000BrakeTest can be used to implement a functional brake test.

This function block is used to switch the AX8000 to torque mode (Cyclic Synchronous Torque Mode (CST)). The torque parameterized at the input is transmitted to the drive as a setpoint. The torque is held until the "Timeout" has elapsed or a feedback ("Succeeded") is sent to the function block. This feedback is typically sent from the safety controller to the PLC. The AX8000 is then set to the original operation mode.

If the brake was not closed before the FB_CoEAX8000BrakeTest was called, or if the brake does not hold the required test torque, then the speed limitation integrated in the AX8000 prevents uncontrolled acceleration of the axis. The velocity limit is parameterized via the "VelocityLimit" variable.

DANGER

Danger to life or risk of serious injury or damage to property due to unintentional movements of the axis

When using the function block, the axis is switched to CST mode. After using the function block (especially after error situations), the axis may still be in CST mode. This can lead to sudden and unplanned movements (especially with lifting axes) when the axis is released.

  • Ensure that there is no hazard as defined by the risk assessment.
  • Check the current operation mode via the function block MC_ReadDriveOperationMode.
  • If the axis is not in a position-related operation mode (CSV/CSP), transfer it before an enable:
    – directly with MC_WriteDriveOperationMode into the desired position-related operation mode (CSV/CSP) or
    – indirectly with MC_Halt / MC_Stop into the desired position-related operation mode (CSV/CSP) (from TwinCAT 3.1.4024.40)
    Other function blocks that switch the axis indirectly into a position-related operation mode can only do this to a limited extent and are therefore not to be used for a deliberate operation mode change.
  • Subsequently, it is necessary to check again whether the axis is really in a position-related operation mode (CSV/CSP), if not, an abort with error handling is required.

Information on the necessary changes in the configuration of the AX8000 can be found in the AX8000 | Multi-axis servo system Functional description.

FB_CoEAX8000BrakeTest 2: Inputs

VAR_INPUT
     Execute       : BOOL;
     Succeeded     : BOOL;
     Torque        : LREAL;
     VelocityLimit : LREAL;
     Timeout       : TIME;
END_VAR

Name

Type

Description

Execute

BOOL

The function block is enabled via a positive edge at this input.

Succeeded

BOOL

Feedback that the brake has held the specified torque. This feedback usually comes from the safety controller.

Torque

LREAL

Torque that should be effective [Nm].

VelocityLimit

LREAL

Velocity limit to prevent uncontrolled acceleration in torque mode.

Timeout

TIME

Maximum time for which the specified torque is effective.

FB_CoEAX8000BrakeTest 3: Inputs/outputs

VAR_IN_OUT
   Axis : AXIS_REF;
END_VAR

Name

Type

Description

Axis

AXIS_REF

Axis data structure that unambiguously addresses an axis in the system. Among other parameters it contains the current axis status, including position, velocity or error state.

FB_CoEAX8000BrakeTest 4: Outputs

VAR_OUTPUT
    Busy : BOOL;
    Error : BOOL;
    ErrorID : UDINT;
END_VAR

Name

Type

Description

Busy

BOOL

This output is set when the function block is activated, and remains set until a feedback is received.

Error

BOOL

This output is set after the Busy output has been reset when an error occurs in the transmission of the command.

ErrorID

UDINT

In the event of a set error output returns the ADS error code.

Requirements

Development environment

Target platform type

PLC libraries to include

Firmware version

Revision

TwinCAT ≥ 4022.36

TwinCAT ≥ 4024.15

PC or CX (x86 or x64)

Tc2_MC2_Drive ≥V3.3.23.0