PLCopen Homing Methods

The following common homing The homing procedure allows, based on a position measurement, to set a position offset to the motor to ensure it is physically at the home position. methods (among others) can be performed in PLCopen A vendor -and product- independent worldwide association active in Industrial Control and aiming at standardizing PLC file formats based on XML.. This section details the setting of the ADK parameters and the PLCopen function blocks A function block groups an algorithm and a set of private data. It has inputs and outputs. to accomplish these methods.

PLCopen does not limit you to these methods, as the capture engine is very configurable.

Home using Current Position

Homing using the current position Position means a point in space which is described by different coordinates. Depending on the used system and transformation it can consist of a maximum of six dimensions (coordinates).This means three Cartesian coordinates in space and coordinates for the orientation. In ACS there can be even more than six coordinates. If the same position is described in different coordinate systems the values of the coordinates are different. is simply accomplished using the MC_SetPos function A function calculates a result according to the current value of its inputs. A function has no internal data and is not linked to declared instances. block. Using this function block, the current position can be set to any value.

Find Input

Homing using a drive In electrical engineering, a drive is an electronic device to provide power to a motor or servo. Control device for regulating the speed, torque and position of a motor. A unit controlling a motor using the current and timing in its coils. input is accomplished by configuring the AKD capture engine, and then using the MC_Reference function block. The following capture engine parameters need to be configured, along with the following input parameters in the MC_Reference.

• Capture Event has to be set to ignore preconditions (0)
• Capture edge – capture edge is programmed The act of performing a sequence of instructions or commands. in the MC_Referece block
• Capture Trigger must be set to the desired drive input (0-6)
• Capture mode must be set to capture position (0)
• Capture preselect is not used
• Capture Precondition edge is not used
• MC_Reference inputs:
  Trigger_Ref.InputID must be set to 0 or 1 to select which AKD capture engine to use
  Trigger_Ref.Direction The orientation components of a vector in space. must be set to Rising (1) or Falling (2) to select Capture Edge
  Trigger_Ref.Trigid is not required.
  Position input must be programmed to the desired position at the switch.
  Option input must be programmed to 0 for "use latched The control word is used to activate the drive's latch status machine. The latch control word is processed independently of the EtherCAT® bus cycle. The status word is used to return the drive's latch status. position".

Find Input then find Zero Angle

Homing using a drive input along with the zero angle Mechanical zero angle of the feedback = 0 degree. is similar to "Find Input" except the position is defined at the zero angle of the feedback device A process where some proportion of the output signal of a system is passed (fed back) to the input. In automation, a device coupled to each motor to provide indication of the motor's shaft angle, for use in commutating the motor and controlling its speed and position. Some systems use a feedback device connected to the motor shaft or part of the driven mechanism to control the direction, acceleration and speed of the motor., rather than the switch location. It is typically used for resolver feedback.

• Capture Event must be set to ignore preconditions (0)
• Capture edge – capture edge is programmed in the MC_Referece block
• Capture Trigger must be set to the desired drive input (0-6)
• Capture preselect is not used
• Capture Precondition edge is not used
• Capture mode must be set to capture position (0)
• MC_Reference inputs:
  Trigger_Ref.InputID must be set to 0 or 1 to select which AKD capture engine to use.
  Trigger_Ref.Direction must be set to Rising (1) or Falling (2) to select switch capture edge.
  Trigger_Ref.Trigid is not required.
  Position input must be programmed to the desired position at the null closest to the switch.
  Option input must be programmed to identify the number of poles the resolver has.

Find Input then find Index

Homing using a drive input along with the index Zero pulse (zero signal) of a hardware pin such as digital input or feedback pin. is similar to "Find Input" except the position is defined at the index pulse A single generated by a second track on the encoder emitter disk that occurs once per revolution. This can be used to indicate an absolute position of the motor shaft. Encoder manufacturers identify the index pulse using different terms such as index, marker, home position, or zero reference. of the feedback device, rather than the switch location. It is typically used for incremental encoder The incremental encoder is simpler in design than the absolute encoder. It consists of two tracks and two sensors whose outputs are called channels A and B. As the shaft rotates, pulse trains occur on these channels at a frequency proportional to the shaft speed. The phase relationship between the signals yields the direction of rotation. AKA: Relative encoder. feedback. To accomplish this, a precondition is used in the capture engine. Specifically, the input is the precondition, and the index is the event. The reference method looks for the switch first, and then the index pulse When the step gets activated, the action is activated for a single execution, and possibly once again when the step is deactivated..

• Capture Event must be set to the desired switch operation. Typically set to 1 to require the edge of the switch. Set to 2 or 3 if the state of the switch is required.
• Capture preselect must be set to the desired drive input (0-7)
• Capture edge – capture edge of index pulse is programmed in the MC_Referece block
• Capture Trigger must be set to the desired index input (10 = primary index,11 = tertiary index)
• Capture mode must be set to capture position (0)
• MC_Reference inputs:
  Trigger_Ref.InputID must be set to 0 or 1 to select which AKD capture engine to use
  Trigger_Ref.Direction must be set to Rising (1) or Falling (2) to select Capture Edge
  Trigger_Ref.Trigid is not required.
  Position input must be programmed to the desired position at the index pulse.
  Option input must be programmed to 0 for "use latched position".

Find Index

Homing using a drive index pulse is accomplished by configuring the AKD capture engine, and then using the MC_Reference function block. The following capture engine parameters need to be configured, along with the following input parameters in the MC_Reference.

• Capture Event must be set to ignore preconditions (0)
• Capture edge – capture edge is programmed in the MC_Referece block
• Capture Trigger must be set to the desired index input (10 = primary index,11 = tertiary index)
• Capture mode must be set to capture position (0)
• Capture preselect is not used
• Capture Precondition edge is not used
• MC_Reference inputs:
  Trigger_Ref.InputID must be set to 0 or 1 to select which AKD capture engine to use
  Trigger_Ref.Direction must be set to Rising (1) or Falling (2) to select Capture Edge
  Trigger_Ref.Trigid is not required.
  Position input must be programmed to the desired position at the index pulse.
  Option input must be programmed to 0 for use latched position.