Motors control

This is the basic Python class to control motor devices by using EPICS set of tools to provide the minimal infrastructure for use in managing and operating motor devices by reading and/or setting their record fields - also known as PVs, Process Variables.

You will find below a set of methods which is available at this version of the Motor’s class with their expected input parameters and/or waited results (if any), describing involved data types.

Using the EPICS Motors control module

Usage of Python class using basic Motor Record fields.

class py4syn.epics.MotorClass.Motor(pvName, mnemonic)

Class to control motor devices via EPICS.

Examples

>>> from py4syn.epics.MotorClass import Motor
>>>    
>>> def createMotor(pvName="", mne=""):
...    
...    new_motor = ''
...    
...    try:
...        new_motor = Motor(pvName, mne)
...            print "Motor " + pvName + " created with success!"
...    except Exception,e:
...        print "Error: ",e
...    
...    return new_motor

Constructor See py4syn.epics.StandardDevice

Parameters:

pvName : string

Motor’s base naming of the PV (Process Variable)

mnemonic : string

Motor’s mnemonic

calculateBacklash(target)

Calculates the backlash distance of a given motor

Returns:

`double`

canPerformMovement(target)

Check if a movement to a given position is possible using the limit values and backlash distance

Returns:

`boolean`

.. note::

• True – Motor CAN perform the desired movement;
• False – Motor CANNOT perform the desired movement.

canPerformMovementCalc(target)

Check if a movement to a given position is possible using the limit values and backlash distance calculating the values

Returns:

`boolean`

.. note::

• True – Motor CAN perform the desired movement;
• False – Motor CANNOT perform the desired movement.

getAcceleration()

Get the motor acceleration time based on the ACCL (Seconds to Velocity) field from Motor Record

Returns:

`double`

getBacklashDistanceValue()

Read the motor backlash distance based on the BDST (Backlash Distance, EGU) field of Motor Record

Returns:

`double`

getDescription()

Read the motor descrition based on the DESC field of Motor Record

Returns:

`string`

getDialHighLimitValue()

Read the motor dial high limit based on the DHLM (Dial High Limit) field of Motor Record

Returns:

`double`

getDialLowLimitValue()

Read the motor dial low limit based on the DLLM (Dial Low Limit) field of Motor Record

Returns:

`double`

getDialPosition()

Read the motor target DIAL position based on the DVAL (Dial Desired Value) field of Motor Record

Returns:

`double`

getDialRealPosition()

Read the motor DIAL real position based on the DRBV (Dial Readback Value) field of Motor Record

Returns:

`double`

getDirection()

Read the motor direction based on the DIR (User Direction) field of Motor Record

Returns:

`integer`

.. note::

0. Positive direction;
1. Negative direction.

getEGU()

Read the motor engineering unit based on the EGU (Engineering Units) field of Motor Record

Returns:

`string`

getFreezeOffset()

Read the motor freeze offset based on the FOF (Freeze Offset) field of Motor Record

Returns:

`integer`

getHighLimitValue()

Read the motor high limit based on the HLM (User High Limit) field of Motor Record

Returns:

`double`

getLVIO()

Read the motor limit violation LVIO (Limit Violation) field of Motor Record

Returns:

`short`

getLowLimitValue()

Read the motor low limit based on the LLM (User Low Limit) field of Motor Record

Returns:

`double`

getOffset()

Read the motor offset based on the OFF (User Offset, EGU) field of Motor Record

Returns:

`string`

getPosition()

Read the motor target position based on the VAL (User Desired Value) field of Motor Record

Returns:

`double`

getRawPosition()

Read the motor RAW position based on the RVAL (Raw Desired Value) field of Motor Record

Returns:

`double`

getRawRealPosition()

Read the motor RAW real position based on the RRBV (Raw Readback Value) field of Motor Record

Returns:

`double`

getRealPosition()

Read the motor real position based on the RBV (User Readback Value) field of Motor Record

Returns:

`double`

getSETMode()

Checks if the motor is in SET mode

Note

Motor will NOT move until it is in in USE mode

getValue()

Get the current position of the motor. See py4syn.epics.IScannable

Returns:

`double`

Read the current value (Motor Real Position)

getVariableOffset()

Read the motor variable offset based on the VOF (Variable Offset) field of Motor Record

Returns:

`integer`

getVelocity()

Get the motor velocity based on the VELO (Velocity, EGU/s) field from Motor Record

Returns:

`double`

homeForward()

Move the motor until it hits the forward limit switch or the software limit.

homeReverse()

Move the motor until it hits the reverse limit switch or the software limit.

isAtHighLimitSwitch()

Check if a motor high limit switch is activated, based on the HLS (At High Limit Switch) field of Motor Record

Returns:

`boolean`

.. note::

• True – Motor is at High Limit;
• False – Motor is NOT at High Limit.

isAtLowLimitSwitch()

Check if a motor low limit switch is activated, based on the LLS (At Low Limit Switch) field of Motor Record

Returns:

`boolean`

.. note::

• True – Motor is at Low Limit;
• False – Motor is NOT at Low Limit.

isMoving()

Check if a motor is moving or not based on the callback

Returns:

`boolean`

.. note::

• True – Motor is moving;
• False – Motor is stopped.

isMovingPV()

Check if a motor is moving or not from the PV

Returns:

`boolean`

.. note::

• True – Motor is moving;
• False – Motor is stopped.

setAbsolutePosition(pos, waitComplete=False)

Move the motor to an absolute position received by an input parameter

Parameters:

pos : double

The desired position to set

waitComplete : boolean (default is False)

Note

If True, the function will wait until the movement finish to return, otherwise don’t.

setAcceleration(accl)

Set the motor acceleration time based on the ACCL (Seconds to Velocity) field from Motor Record

Parameters:

accl : double

The desired acceleration to set

setDialHighLimitValue(val)

Set the motor dial high limit based on the DHLM (Dial High Limit) field of Motor Record

Parameters:

val : double

The desired value to set

setDialLowLimitValue(val)

Set the motor dial low limit based on the DLLM (Dial Low Limit) field of Motor Record

Parameters:

val : double

The desired value to set

setDialPosition(pos, waitComplete=False)

Set the motor target DIAL position based on the DVAL (Dial Desired Value) field of Motor Record

Parameters:

pos : double

The desired position to set

waitComplete : boolean (default is False)

Note

If True, the function will wait until the movement finish to return, otherwise don’t.

setEGU(unit)

Set the motor engineering unit to the EGU (Engineering Units) field of Motor Record

Parameters:

unit : string

The desired engineering unit.

Note

Example: “mm.”, “deg.”

setFreezeOffset(val)

Set the motor freeze offset based on the FOF (Freeze Offset) field of Motor Record

Parameters:

val : integer

The desired value to set

setHighLimitValue(val)

Set the motor high limit based on the HLM (User High Limit) field of Motor Record

Parameters:

val : double

The desired value to set

setLowLimitValue(val)

Set the motor low limit based on the LLM (User Low Limit) field of Motor Record

Parameters:

val : double

The desired value to set

setOffset(val)

Set the motor offset based on the OFF (User Offset, EGU) field of Motor Record

Parameters:

val : double

The desired value to set

setRawPosition(position)

Sets the motor RAW position based on the RVAL (Raw Desired Value) field of Motor Record

Returns:

`double`

setRelativePosition(pos, waitComplete=False)

Move the motor a distance, received by an input parameter, to a position relative to that current one

Parameters:

pos : double

The desired distance to move based on current position

waitComplete : boolean (default is False)

setSETMode()

Put the motor in SET mode

Note

Motor will NOT move until it is in in USE mode

setUSEMode()

Put the motor in USE mode

setUpdateRequest(val)

Set the motor update request flag based on the STUP (Status Update Request) field from Motor Record

Parameters:

val : integer

The desired value to set for the flag

setValue(v)

Set the desired motor position. See py4syn.epics.IScannable

Parameters:

v : double

The desired value (Absolute Position) to set

setVariableOffset(val)

Set the motor variable offset based on the VOF (Variable Offset) field of Motor Record

Parameters:

val : integer

The desired value to set

setVelocity(velo)

Set the motor velocity up based on the VELO (Velocity, EGU/s) field from Motor Record

Parameters:

velo : double

The desired velocity to set

stop()

Stop the motor

validateLimits()

Verify if motor is in a valid position. In the case it has been reached the HIGH or LOW limit switch, an exception will be raised.

wait()

Wait until the motor movement finishes