The controller comprises a computer and amplifier. There are two connections - one to earth, and one for the pipette headstage. In spatch, each pipette requires its own controller. In effect, when there are multiple controllers, they communicate invisibly between themselves to synchronise their recordings.
The signal to the pipette may be either a constant voltage or current set with the mode variable, and the corresponding V_hold or I_hold, or it may be a predefined command profile.
The simplest command is a block based profile. Setting the preferences userLevel to advanced allows you to specify instead a more flexible (but more complicated) stepped profile. If the former is not set it will appy that, then look for the latter, then if neither is set the constant holcing voltage or current will be used.
Recordings are made for the duration of the applied protocol with a sampling interval set in the SampleInterval field, in milliseconds. So for example a value of 0.5 here corresponds to sampling at 2 kHz. Note that this is unrelated to the timestep used in the calculation which, itself, is set in the parameters object.