There is the class AttributeMotor that allows us to treat an arbitrary attribute as a motor. Here is an example for a configuration:
This motor is introduced to Online by these lines (/online_dir/online.xml).
<name>gap</name> <type>type_tango</type> <module>motor_tango</module> <device>p07/attributemotor/gap</device> <control>tango</control> <hostname>hasgksspp07eh2a:10000</hostname> </device>