MX sample changers - the Movie

Click on the above animation for a short movie (large file - ~65Mb) showing how to load and unload your baskets from your shipping dewar and also showing the mechanism of loading and unloading crystals from the goniometer.



There is a page dedicated to troubleshooting sample changer problems here.



The Sample Changer Manual

Quick links:




Turning the Sample Changer On

The Sample Changer Touch Screen

Loading/Unloading Baskets

Loading/Unloading Sample using the Touch Screen

The Sample Changer GUI and Device Server

Controlling the Sample Changer through MXCuBe

Sample Changer Status

Changing Sample Holder Length

Scanning the Contents of a Sample Changer




(Table of Contents)

Eight Sample Changers (SCs), the result of a joint collaborative effort between the ESRF, the EMBL Grenoble outstation and BM14 (MRC France), are installed (see below) on the 7 ESRF MX beam- lines (ID14 - EH1, EH2, EH3, EH4; ID23 - EH1, EH2; ID29) and the CRG beam-line BM14.


This manual describes the routine use (loading/unloading of baskets into the SCs, loading/unloading individual samples onto the host goniometer) of these automatic Sample Changers. Details of maintenance procedures for use by qualified personnel are described elsewhere.

Important: The goniometer head that must be used in conjunction with the SCs is equipped with a SmartMagnet. This detects whether a sample is mounted on the goniometer head or not. Each indivudual SmartMagnet is tuned for operation on a particular beam-line and a goniometer head must NOT be taken from one beam-line for use on another.

Smart Magnet

Important: The Sample Changer has been designed for use with SPINE standard sample holders and vials, which are loaded into the SC in baskets specifically designed for the SCs. Under no circumstances should non-standard sample holders and vials be introduced into the SCs.

Important: Before using the Sample Changer it is important to ensure that all vials are in good condition, i.e. that they are not broken or cracked. Using vials in bad condition is very likely to block or damage the Sample Changer and could result in the loss of crystals and/or beam-time.


(Table of Contents)

Warning notices have been fixed to certain components of the SC. For your safety it is important to follow the instructions given on these. They warn of potential risks such as liquid nitrogen burns, getting fingers caught in moving equipment, electric shocks, etc. In addition:

The metal protective covers of the SC should only be removed under the supervision of qualified ESRF/EMBL staff. These protect the SC but also the user from numerous potential risks.

The Plexiglass protective cover has a hinge which allows it to be opened if necessary. When this cover is opened, the speed of movement of the SC elements is reduced to 10% of the normal speed. This eliminates the risk of injury if the cover is opened while SC elements are moving. Nevertheless, this cover must only be opened by external users when they are under the supervision of a suitably qualified member of ESRF/EMBL staff.

In the case of a SERIOUS emergency, pressing the RED emergency stop button on the front of the SC cuts supplies of both power and compressed air to the SC and compressed air to all the experimental setup (backlight, cryo, etc...) but the phi axis. If this button is pressed and you wish to restart the SC simply turn on the electronic rack and press the red button on the box underneath it.

Sample Changer



Turning the Sample Changer on

(Table of Contents)

Under normal circumstances the different components of the SC will already be powered up and running when external users arrive at the beam-lines and the following instructions are designed for use by Local Contacts. The electronics rack (see picture above) host the PMAC electronic cards to drive and control the sample changer, the rack can be called "PMAC controller", "control rack", "PMAC control rack", "SC electronic rack", etc... in some occasions.

1) Before turning the PMAC controller on check the following:

  • The control rack is connected to the 230V ESRF UPS system (blue sockets).
  • The plug on the back of the control rack which allows the rack to be powered is in place as shown opposite.
  • The large black switch at the back of the rack is in the On position.
  • The "Control Electronics" dial switch on the front of the control rack is turned to the I position.



2) Then turn on the PMAC first using the main 220V switch (Main Supply & Heating) then pressing the Green (Motors Power Supply) button both of which are situated at the front of the PMAC control rack. The touch screen will boot and present its "Main Menu" screen.


 If you need to turn the PMAC off, press the red "Motors Supply" button first, then turn of the "Main Heating & Supply“ switch.

3) Make sure the SC PC is running. If not, start it up (as for a normal Windows PC) and log in (opidxx/tonicxx).

4) Start the SC GUI and lock the latter.

5) To control the SC from outside the experimental hutch first ensure that the touch screen is showing the "sample transfer menu", then start the experimental hutch version of SPEC and mxCuBE on the beam-line control PC. To enable control of the SC from inside the experimental hutch make sure that the experimental hutch version of SPEC is running on the beam-line control PC and start mxCuBE_hutch using the icon on the linux PC in the experimental hutch.

The Sample Changer Touch Screen

(Table of Contents)

As well as being used to control the Sample Changer, the touch screen also allows users to discern its working state. When the Sample Changer is moving, reading or performing other operations, the touch screen displays that the Sample Changer is "Busy", hourglass symbols appear and the title of the screen blinks. When not moving, the text bar at the bottom of the touch screen displays "Ready". External Users of the ESRF MX beam-lines should only use the touch screen when loading/unloading baskets into/from the SC or, under the supervision of a Local Contact, for troubleshooting minor problems (i.e. vial jams)

The screens available on the touch screen of the SC are as follows :




The Sample Transfer screen is shown on starting the SC. This screen allows the loading/unloading of individual samples onto/from the host goniometer head.

The Basket Transfer screen is used to load and unload baskets into the SC.

The Setup General screen allows access to screens used for alignment and trouble-shooting

The numbers in the centre of the screens show, where appropriate, either the current basket position, i.e. the basket position which is aligned with the loading chimney or both the basket and sample position of an individual sample to be loaded. It is possible to select a different position for loading/unloading by using the arrows on either side of this number to change incrementally, or by pressing on the number itself and directly selecting the basket number/sample position desired.

Loading/Unloading Baskets

(Table of Contents)

Important: When handling SC baskets, baskets tongs attached to the right side of the sample changer must be used.


The procedure for loading and unloading baskets is essentially identical.

NOTE : When loading a basket, please check that the basket is correctly positioned at the bottom of the Sample Changer before releasing it. When both loading and unloading, you MUST remove the transfer tool from the Sample Changer before choosing the next basket position.

  1. Go to the "Basket Transfer" screen (see above). When this screen is activated, control of the SC through MxCube is disabled and the SC buttons on the mxCuBE GUI are greyed out.
  2. Select the position where you wish to load/unload a basket.
  3. Remove the blue basket port cover and insert/remove the basket using the transfer tool provided. To grab a basket with the transfer tool, press the button on the top of the tool and push down on the basket. Then release the button and the basket should be held. To release a basket, press on the button again.
  4. Replace the blue basket port cover.
  5. Repeat steps 2) to 4) for each basket to be loaded/unloaded.
  6. Check that the blue basket port cover is replaced once all baskets have been loaded/unloaded. This prevents icing and the Sample Changer will not work without this cover in place
  7. Exit the "Basket Transfer" screen by touching the 'sample transfer' button in order to return to the "sample transfer" screen. When this is done the SC buttons in the MxCube GUI are reactivated.




Loading/Unloading Samples using the Touch Screen

(Table of Contents)

This mode of using the SC is reserved for experienced users & Local Contacts.

The procedure for loading and unloading baskets is essentially identical. Step 1 to 3 are not necessary for ID29.

  1. In the experimental hutch SPEC session running on the beam-line control computer in the control cabin, type the following (NB) You only need to do this at the start of any session where you wish to use the touch screen to load/unload samples:
  2. EXP> SCMinidiffGetControl
  3. EXP> SCMoveToLoadingPosition
  4. Select the basket containing the sample you wish to load/unload.
  5. Select the basket containing the sample you wish to load/unload.
  6. Select the sample sample you wish to load/unload.
  7. Press Load/Unload

For ID29: The flip between the use of Touch Screen or SC tab in mxCuBE for loading/unloading samples doesn't required any command in Spec. The transfer mode in microdiff has to be set to 'Use Sample Changer' (Option-Hardware Setup)



The Sample Changer GUI and Device Server

(Table of Contents)

The Sample Changer (SC) User Interface (GUI) run on PCs situated inside the experimental hutches of the beam-lines. The SC GUI must be running on these PCs in order to be able to control the sample changer remotely (i.e via mxCuBE). The computer screens in the experimental hutch link via a KVM box (next to the screen) to 2 computers :

Local mini-diffractometer control PC : KVM port 1, for minidiff control

Windows PC for controlling SC : KVM port 2, for running the SC device server

The names of the PCs on which the SC GUIs and Device Servers run are as follows:


PC Name


ID14-1 pcsc3-eh1
ID14-4 pcsc3-eh4
ID23-1 pcsc3-id231
ID23-2 pcsc3-id232
ID29 pcsc3-id29

If it is not already running, in order to start the Sample Changer device server and GUI, locate "Sample changer" icon on the computer’s desktop and double click on it. The device server will start and the GUI will appear.







  It is possible to access to the sample changer's PC from each experiment control terminal  by single clicking on the icon names 'VNC to sample changer' which lies on the right desktop of the terminals :




Controlling the Sample Changer through mxCuBE

(Table of Contents)

Once the baskets containing samples have been loaded into the sample changer the SCs should be controlled using the mxCuBE beam-line control GUI available on all the ESRF MX Group beam-lines. Important: The experimental hutch session of SPEC must also be running. If it is not then the elements of the mxCuBE GUI will show in red. Samples are loaded/unloaded using the SC buttons found in the sample changer section of the "Collect" tab while they are centered in the X-ray beam using either the '3-click Centring' or the "Autocentring" buttons in the "Hutch" tab. Data collection can then be launched using fields in the "Collect" tab of the GUI or using the EDNA software.

There are 3 ways to select and mount a sample on the goniometer head (see snapshot below showing the 3 zones of interest):

  • by using the sample list : click right on your sample name (coming from IsPyB) and select mount. It will automatically unmount the actual mounted sample and mount the one you have selected.
  • by using the top part of the sample changer brick : choose the relevant basket and sample positions (this must be done sequentially - i.e basket position followed by sample position) using the buttons available. To load a sample click 'load'. To unload a sample click 'unload'! The previous sample will have to unmounted first by pressing the button "Unmount Sample"
  • by using the bottom part of the SC brick : tick the boxes by the baskets you are working on and double click on the position of your choice. It will unmount the previous sample and mount the one you selected.

Note: As mentioned above, the goniometer head that must be used in conjunction with the SCs is equipped with a SmartMagnet. This detects whether a sample is mounted on the goniometer head or not and the Load/Unload button changes accordingly. It is therefore impossible to request a sample load if there is a sample already loaded or to request an unload when there is no sample mounted.




The sample coloring changes in the bottom part of the SC brick to allow you to see quickly what sample was not mounted yet. After SC scanning, samples for which a barcode was found are displayed with a Data matrix symbol while the others are just plain. Samples which have not been mounted are shown in white while the already mounted samples are shown in cyan. The pin symbol shows the sample which lies at that moment on the goniometer axis (i.e. basket 1 sample 3 in the below exemple)



It is also possible to switch from basket loading mode to sample transfer mode from the mxCuBE GUI in case you forgot doing the switch after your basket loadings:




Sample Changer Status

(Table of Contents)

The green rectangle at the top of the SC area in the "Collect" tab of mxCuBE displays the status of the Sample Changer, using both a status message and a colour code. The different colour codes are :

  • GREEN : sample changer is ready to receive a command (i.e. load/unload, move to new basket position, move to new sample position)
  • YELLOW : sample changer is moving (i.e loading/unloading, moving to new basket or sample position)
  • PURPLE : non-fatal alarm - if you are unfamiliar with the operation of the SCs or using the trouble shooting section of this manual does not cure the problem then please call your Local Contact.
  • RED : fatal error - if this occurs you MUST call you local contact as an intervention on the SC will almost certainly be required.

If the sample changer buttons are greyed out and you are not carrying out a data collection the you have forgotten to make sure that the touch screen is showing the "sample transfer window".

Changing Sample Holder Length

(Table of Contents)

The Sample Changer has been designed for use with SPINE standard sample holders which have a "holder length" of 22 mm. This is the default holder length used by mxCuBE when moving minidiffractometer motors to standard positions for the loading/unloading of samples. However, the use of Mitigen or Litho-loops in conjunction with SPINE sample holders will result in different holder lengths. This can be taken into account using the “Holder length” input field in the SC area of the mxCuBE GUI which allows users to specify the holder length of the pin of any sample to be loaded. Once changed the "Holder length" will remain at its new value and be taken into account when moving the minidiffractometer to its loading position for all the samples in the SC until a new holder length is entered.

Important: The holder length is defined as the distance between the bottom of the base of the sample holder to the centre of the loop in which the sample is mounted. It is NOT the length of the pin in which loops are mounted.

Scanning the Contents of a Sample Changer

(Table of Contents)

Once baskets containing samples are loaded into the sample changer it is then possible to scan its contents and display them in mxCuBE. First select the baskets you want to scan (tick boxes in the sample changer GUI) and press on the "Scan selected basket' buttom below the list of baskets in the bottom part of the SC brick. The list of barcodes will also appear in the sample list (top part of the Collect TAB). If you have also declared your samples in ISPYB (shipment created), and that you have selected them in the "prepare your experiment" within IsPyB, they also will appear in this list after pressing on the "Refresh" button (bottom right of the sample list)

It is also possible to erase a previous scan, if you change your baskets in the sample changer for example, by pressing on the "Reset sample changer contents" from the mxCuBE interface.