Sequencer procedure

   # at start of the sequencer
   connect()     -> for all items: get and open a port object to communicate with a device
   initialize()  -> for all items: set all value and configurations to make the device ready for a measurement
   
   
       # if a Root-To-Leaf is started
       configure()  -> changes the configuration of the device
       poweron()    -> switches the device on
   
           # if a leaf of a Root-To-Leaf is reached
           start()       -> for all items of the Root-To-Leaf: prepare something before value is applied
           apply()       -> for all items of the Root-To-Leaf: set the new value to a device if supported 
           sleephold()   -> for all items of the Root-To-Leaf: sleep the hold time while the value is applied to the device
           trigger()     -> for all items of the Root-To-Leaf: make device ready to be triggered
           measure()     -> for all items of the Root-To-Leaf: initiate the measurement or send a trigger
           call()        -> for all items of the Root-To-Leaf: read the results from the port buffer
           process()     -> for all items of the Root-To-Leaf: use the chance to postprocess your data
           finish()      -> for all items of the Root-To-Leaf: clean up before the next measurement starts 
           sleepstop()   -> for all items of the Root-To-Leaf: sleep the stop time while the device is set to its idlevale
     
       # if a Root-To-Leaf is left
       poweroff()      -> for all items: switches the device off
       unconfigure()   -> set value to idlevalue and apply() it
   
   # at end for all items of the sequencer
   deinitialize()   -> for all items: reset the status for any other user of the equipment
   disconnect()     -> for all items: closes the port object