2.3.2.1. DAQ Move

This module is used to control any Actuator hardware. An Actuator is, in a general sense, any parameter that one can control and may vary during an experiment. The default actuator is a Mock one (a kind of software based actuator displaying a position and accepting absolute or relative positioning).

2.3.2.1.1. Introduction

This module when used as a standalone application has a UI in the form of a toolbar with several buttons and widgets allowing the actuator type selection and initialization as well as the current value display and some other functionalities described below. Fig. 2.9 shows the minimal interface of the module (in order to take minimal place in the Dashboard)

daq_move_gui_base

Fig. 2.9 Minimal DAQ_Move user interface

Note

In this interface, many general options are available in the menus such as acces to the log, preferences… These are shared with all PyMoDAQ user interfaces and are described in the Shared UI section

2.3.2.1.2. Hardware initialization

  • select: list of available instrument plugins of actuator type, see Fig. 2.10.

  • init: Initialize/Desinitialize the hardware using the current settings

  • quit: De-initialize the hardware and quit the module

daq_move_gui_base

Fig. 2.10 Menu list displaying the available instrument plugin of type DAQ_Move

2.3.2.1.3. Specialized User Interfaces

In fact the UI adapts itself to the peculiarities of the chosen actuator: either able to do absolute positioning or not (relative only) or binary (can only set two different values). The core ui is depicted on Fig. 2.11

daq_move_gui_base_base

Fig. 2.11 The base UI shared by all specialized interfaces

Note

The choice of the UI is done given several options with an order of priorities:

  1. The actuator plugin class defined a particular one (or None)

  2. if (1) is ‘None’ (default) the UI is set according to the Preferences: pymodaq/actuator/ui (see Configuration file)

  3. if (1) is ‘None’ (default) and in DashBoard, the value chosen in the Experiment Manager is used (see Experiment manager)

2.3.2.1.3.1. Default User Interface

The interface depicted on Fig. 2.9 is the default one used for actuators with encoders (or equivalent) able to do absolute value/positioning using dedicated widgets/buttons (see Fig. 2.12).

absolute_positioning

Fig. 2.12 The UI components to perform absolute positioning

2.3.2.1.3.1.1. Setting the Actuator’s value

Once the hardware is initialized, the actuator’s value is displayed on the Current value display (right of the settings button) while the absolute value can be set using one of the top spinbox (respectively green or red) and apply it using respectively the green_arrow or red_arrow button. This double positioning allows to quickly define two values and switch between them.

2.3.2.1.3.1.2. Advanced functionalities

More options can be displayed in order to precisely control the actuator by pressing the plus_button button. The user interface will then look like Fig. 2.13.

daq_move_gui_rel

Fig. 2.13 DAQ_Move user interface with finer controls

The two new displayed spinbox relate to Absolute positioning and Relative one.

  • home: the actuator will try to reach a home position (known position or physical switch limit)

  • abs: the actuator will try to reach the set absolute position

  • move_rel: the actuator will try to reach a relative position (+increment)

  • move_rel_m: the actuator will try to reach a relative position (-increment)

  • where: will update the current actuator’s value display

2.3.2.1.3.1.3. Other actions

Other actions present in the toolbar allow to:

  • stop: stop the current motion (if possible)

  • display: stop the current motion (if possible)

  • refresh: Refresh the current value periodically (period can be set in the settings)

2.3.2.1.3.2. Binary User Interface

For actuators that need only to set two different values (like beam shutters, relays, …), the Binary ui can be used and is displayed on figure Fig. 2.14

daq_move_gui_base_binary

Fig. 2.14 Specialized UI for binary actuators

In this UI the absolute green and red spinboxes have been removed as only two values can be set (one is represented as the green value and the other as the red value). The exact binary values can be set in the actuator settings (see purple rectangle in figure Fig. 2.16)

2.3.2.1.3.3. Relative User Interface

daq_move_gui_base_relative

Fig. 2.15 Specialized UI for relative only actuators

In this UI the absolute green and red spinboxes have been replaced with a relative one while the green/red absolute move buttons have been replaced with the move up and down button allowing increment (relative value set in the spinbox) in the positive or negative direction.

The current value is still displayed but this is the result of an internal encoding mechanism remembering the number and value of previously done increments. This is purely software based and may be incorrect in term of absolute values after a few increments. The reset button allows to reset this encoding to zero!

2.3.2.1.4. Settings

The hardware and module settings can be displayed by pressing the settings button. The user interface will then look like Fig. 2.16.

daq_move_gui_settings

Fig. 2.16 Full DAQ_Move user interface with controls and settings

In the settings tree, there is two sections. The first relates to the Main settings of the actuator while the second relates to the hardware settings (the ones the hardware will need in order to initialize…). There is also specific settings explained below.

2.3.2.1.4.1. Main Settings

  • Actuator type: is recalling the instrument plugin class being selected

  • Actuator name: is the name as defined in the experiment (otherwise it is defaulted to test)

  • UI type: is recalling the chosen UI for the current actuator

  • Refresh value: is the timer duration when grabbing refresh the actuator’s current value.

  • Value Green: default value for the green spinbox (allows the StateManager to configure it)

  • Value Red: default value for the red spinbox (allows the StateManager to configure it)

  • Value Relative: default value for the relative spinbox (allows the StateManager to configure it)

  • LECO: related to communication over the network, see LECO communication.

2.3.2.1.4.2. Multiaxes controller

Sometimes one hardware controller can drive multiple actuators (for instance a XY translation stage). In the simplest use case, one should just initialize the instrument plugin and select (in the settings) which axis to use, see Fig. 2.17 (orange rectangle).

daq_move_gui_settings

Fig. 2.17 Display of the full interface with the advanced controls and the settings.

Then the selected axis can be driven normally and you can switch at any time to another one.

It is more complex when you want to drive two or more of these multi-axes in the DashBoard, for instance to perform a scan. Indeed, each one should be considered in the Dashboard as one actuator. But if no particular care is taken, the Dashboard will try to initialize the controller multiple times, but only one communication channel exists, for instance a COM port. The solution in PyMoDAQ is to identify one actuator (one axis) as Master and the other ones will be referred to as Slave. They will share the same controller address (and actual driver, wrapper, …) represented in the settings tree by the Controller ID entry.

  • Controller Status: Master or Slave

  • Controller ID: unique identifier of the controller driving the stage

  • Axis: Combobox to select the axis this UI should drive (the list of axes is defined by the developer in the actuator plugin class)

These settings are really valid only when the module is used within the Dashboard framework that deals with multiple modules at the same time as configured in the Experiment manager interface.

2.3.2.1.4.3. Bounds

if this section is activated (by clicking the Set Bounds entry) then the actuator values will be software limited between min and max. This can be used to prevent the actuator to reach dangerous values for the experiment or anything else.

2.3.2.1.4.4. Scaling

If this section is activated (by clicking the Use scaling entry) then the set and displayed positions will be scaled as:

new_position=scaling*old_position+offset

This can be useful for instance when one deals with translation stage used to delay a laser pulse with respect to another. In that case it is easier to work with temporal units such as femtoseconds compared to mm or other native controller unit.

2.3.2.1.4.5. Other settings

  • epsilon: -very important feature- the actuator will try to reach the target position with a precision epsilon. So one could use it if one want to be sure the actuator really reached a given position before moving on. However if the set precision is too small, the actuator may never reached it and will issue a timeout

  • Timeout: maximum amount of time the module will wait for the actuator to reach the desired position.

2.3.2.1.5. Configuration file

A dedicated entry is present in the toml main configuration file for the DAQ_Move to tailor the module’s behaviour. The various field are written below together with their meaning

[actuator]
ui = ['Simple', 'Relative', 'Binary'] #other eventual options will be added programmaticaly at startup
epsilon_default = 1
polling_interval_ms = 100  # ms Careful when using TCP/IP connection as you can saturate the connection with too much polling
polling_timeout_s = 20  # s
refresh_timeout_ms = 500  # ms
siprefix = true  # tell if printing of current value use a SI prefix or not (µ, m, k, M...)
siprefix_even_without_units = false
display_units = true # display units in the SpinBoxes
default_value_red = 0.0
default_value_green = 1.0
default_value_relative = 1.0

  • epsilon_default: default value for the actuator precision

  • polling_interval_ms: interval in millisecond for refreshing the actuator’s value

  • polling_timeout_s: Timeout in seconds during which the DAQ_Move tries to reach its target

  • refresh_timeout_ms: interval in millisecond for probing the actuator’s value in continuous mode

  • siprefix: tell if printing of current value use a SI prefix or not (µ, m, k, M…)

  • siprefix_even_without_units: in case the controller is dimensionless (steps, …) it could be misleading to include a SI Prefix (as m could be understood either as meter or milli”nothing”). This boolean is False by default (no SI Prefix when dimensionless) but this behaviour could be changed here

  • display_units: display units in the SpinBoxes

  • default_value_red: initial default value displayed in the red spinbox

  • default_value_green: initial default value displayed in the green spinbox

  • default_value_relative: initial default value displayed in the relative spinbox