Sardana provides widgets for plotting scans either online or offline. Currently there are two different widgets for providing these features. These widgets can be used in your GUI or launched from spock.

Showscan online

Showscan online is a simplified Taurus application which provides live scan plots. The number of plots and their configuration depends on the measurement group plotting configuration.

It can be launched from Spock using the showscan command:

LAB-01-D01 [1]: showscan online

or with the console command: showscan.

When started it gets populated with empty plots of the active measurement group. As soon as you start scanning the curves and the legend will start to appear. Even if you change the active measurement group or you change the plotting configuration the plots will not get recreated until you start another scan. The purpose of this behavior is to keep the plotted data available for inspection after the scan execution.


Showscan online plotting one physical counter against the motor’s position.

Another interesting feature of this widget is its multi plot organization when you ask for plotting multiple curves. You can choose between having a separate plot per curve or group curves by the selected x axis


Showscan online plotting three physical counters against the motor’s position on separate plots.

Finally, the scan point and the scan information panels are available and offer online updates on the channel values of the current scan point and some general scan information e.g. scan file, start and end time, etc. respectively.


Showscan online plotting with separate plots and information panels.

Showscan offline

Showscan is basically a simple HDF5 viewer application. It can be launched from Spock using the showscan command. Without arguments, it will show you the result of the last scan in a GUI:


Scan data viewer in action

showscan scan_number will display data for the given scan number.


The showscan application can only read scans saved in the HDF5 format.

The scan files are saved on the Sardana server machine, however showscan is running on the client one. If it’s not the same machine, you will need to share the scan files between machines, for example with NFS.


If the path to the file on the server is different than on the client, you should use DirectoryMap environment variable to map server paths to client paths.

In order to use the showscan widget while scanning, you will need to use the HDF5 write session in the SWMR mode, for example:

LAB-01-D01 [1]: newfile /tmp/scans.h5
ScanDir is      : /tmp
ScanFile set to : scans.h5
Next scan is    : #1

LAB-01-D01 [2]: h5_start_session True
H5 session open for '/tmp/scans.h5'
        SWMR mode: True
        HDF5 version compatibility: ('v110', 'v110')

LAB-01-D01 [3]: showscan
Trying to open local scan file /tmp/scans.h5...

LAB-01-D01 [4]: # now you can execute scans without the need to close the showscan

Otherwise, you will need to close the showscan for every new scan execution.