Slits configuration¶

This chapter presents a typical usage of BLISS to configure and test standard slits.

The example is based on configuration of secondary slits of ID21.

To ease readability, the configuration of only one pair of blade is described here, but the example can easily be extended to 2 pairs.

Real motors¶

First part of the file is the configuration of real motors. In the case of the slits of ID21, the real motors are driven by Icepap. Icepap configuration gives full details of Icepap motors configuration.

Note the negative sign to fix cabling choice: user convention is to be positive when opening slits

NB: name field is mandatory for Beacon Web Config tool to recognize device as a motor.

-
  controller:
    class: IcePAP
    host: iceid219
    name: secondary_blades
    axes:
        -
            name: ssf
            address: 23
            steps_per_unit: -1000     <--- negative sign.
            velocity: 1
            acceleration: 8
            backlash: 0.05
        -
            name: ssb
            address: 24
            steps_per_unit: -1000
            velocity: 1
            acceleration: 8
            backlash: 0.05

Virtual axes¶

Second part is the configuration of new virtual axes based on real axes.

The role of each blade is defined using the tags keyword
- real means the axis is a real motor, declared elsewhere
- front, back, hgap, hoffset are specifiers for each axis
The plugin is not specified in secondary_slits.yml, because a __init__.yml with plugin: emotion already exists in the directory
slit_type: can be horizontal or vertical or both (default value)

no_offset: can be True or False (default True)

-
  controller:
    class: slits
    name: secondary_slits
    slit_type: horizontal
    no_offset: True # default is True
    axes:
        -
            name: $ssf  <----------  The existing 'ssf' axis,
            tags: real front  <----  has got the role of *real front* axis.
        -
            name: $ssb
            tags: real back
        -
            name: sshg <------------ The (new) virtual axis 'sshg',
            tags: hgap      <------- is the *horizontal gap* axis.
            tolerance: 0.04
        -
            name: ssho <------------ The (new) virtual axis 'ssho',
            tags: hoffset   <------- is the *horizontal offset* axis.
            tolerance: 0.04

Horizontal Slits Example

Stable slits¶

Stable slits have the second (move) motor held by the moving part of the first (support) motor. Hence, moving the offset consist in moving only the first (support) motor.

This improves the stability of the slits: less vibrations and a constant gap.

  Support
   ___
  | 1 |_______________________________
  |___|     |                         |
            |                |        |
           _|_               |        |
          | 2 |______________|
          |___|
           Move
                         ___
                        | 1 | Support
                        |___|
                          |
              ___         |
        Move | 2 |________|
             |___|        |
               |          |
               |          |
               |    ______|
               |
               |
               |
               |_______

NB: Due to cabling conventions, one of the motors must have a negative sign.

Configuration example:

- plugin: emotion
  class: StableSlits
  type: horizontal
  name: edss_horizontal_id24
  axes:
    - name: $edssh
      tags: real move
    - name: $edssr
      tags: real support
    - name: edsshg
      tags: gap
      unit: mm
    - name: edssho
      tags: offset
      unit: mm

- plugin: emotion
  class: StableSlits
  type: vertical
  name: edss_vertical_id24
  axes:
    - name: $edsst
      tags: real support
    - name: $edssb
      tags: real move
    - name: edssvg
      tags: gap
      unit: mm
    - name: edssvo
      tags: offset
      unit: mm