The following preconditions must be fulfilled before external control elements can be used for live control and recording of data:
The input device must be configured in the Media Pool. The input devices in question are listed in topic Using external input devices.
The control elements must be linked up with objects. See Allocating control elements.
Moreover, the values of 
Value-In variables can be recorded in data objects.
When using external control elements, switch and data objects can be put into various modes. Select the mode by right-clicking a switch or data object:
Playback ... is the standard mode of switch and data objects, external control elements are not effective.
Live ...when recording is active, the control element can be used for controlling although no recording takes place. The values or ramps used in the objects are not considered.
Start recording ... after recording has been started the control element can be used for controlling. The values or ramps in the object are overwritten.
Record-> Play ...as above, but after stopping the object is put into mode Playback of recording. For further recording a Record mode must again be activated for the object.
Playback of recording ...marks a data object as recorded.
Record Punch In/Out ...activates recording during playback. This option allows certain object portions to be overwritten during playback. To enable Punch In and Punch Out you need to create the corresponding triggers, which may be linked up with certain keys. Further information can be found here.
And this is how it is done:
Right-click the corresponding data object, select Mode and Live, Start recording, Record->Playback or Record Punch In/Out. The active mode is displayed at the beginning of the info line. If you want to change the mode for several objects simultaneously, you need to highlight them before you can do so.
Move the Locator to a position before the switch or data object or to the position where control is to start.
If the device control has not been enabled yet, click on 
Enable device ports in the function bar below the main menu. Please note that recording is only possible when the data or switch objects are linked up with at least one output channel.
Start recording by enabling 
Record Mode in the tool bar, followed by pressing the space bar. Alternatively, you can press the Record key on the Mackie Control (if applicable). See also Mackie Control Functions. The length of the data object corresponds to the time window that allows remote controlling or recording. In Record Punch In/Out Mode recording only starts with Punch In and finishes with Punch Out.
Now actuate the corresponding control element for input. During recording, the recorded values are immediately displayed in the data object.
Stop recording by pressing the Esc key or the Stop key of connected controllers. When objects were in mode Record-> Play they change to mode Playback of recording.
The ramp bands in the data objects created thus can be edited with the mouse. Usually, they show a high number of nodes which make editing quite impossible. This is why you should remove any superfluous nodes beforehand. See Simplifying ramps and Editing the ramp band.
Important: In order to record data in a switch or data object, at least one control channel must be assigned for output, i.e. a DMX channel or a switch channel, for example.
As an alternative, you can start recording by pressing keys Ctrl and R.
Recording of a certain portion only is very elegantly done via the Punch In/Out function and trigger markers. See Recording via Punch In/Out.
Object modes Play, Live, Start recording, etc. can also be altered for a whole series of objects, by marking them prior to changing their mode. See Marking objects.
Display of node values should be deactivated, otherwise the course of the ramp is not clearly visible. See Displaying values in objects.
You can invert the recorded ramp shape of data objects. See Inverting ramp shapes or switching states.
Any redundant switch points (gray, vertical lines) created by setting switching with the mouse or via data recording can be removed. Right-click the corresponding switch object and select Switch points 
Remove redundant points.
You can remove all switch points by right-clicking the switch object and selecting Switch points Reset.