Tango, Sardana, Attribute as a Counter

An attribute can be made available as a counter by adding an entry to /online_dir/online.xml:

<device>
 <name>double_scalar</name>
 <type>counter</type>
 <module>tangoattributectctrl</module>
 <device>sys/tg_test/1/double_scalar</device>
 <control>tango</control>
 <hostname>hasXXX:10000</hostname>
</device>

The device double_scalar will be created by the next SardanaAIO.py -x.