Dimension Engineering's Sabertooth 2x32 Analog DIP Switch Settings
I shall define the control signal as follows:
The control signal would be an voltage if you chose the analog version. If you chose radio then it would be a pulse of a width of (probably) 1000us (0%) to 2000us (100%) being the extremes, with 1500us being the center (50%).



DIP Switch 6 determines whether the motors are allowed to reverse direction.

DIP Switch 4 is responsible for independent and mixed:

Independent: Each motor has its own control signal. Simple.

Mixed: Both motors SHARE TWO control signals. Conceptually each signal determines the following:


the first control signal (which I will call the throttle) will determine
the average RPM of both motors.
the second control signal (which I will call the differential) determines the difference in RPM between the motors (direction included so -100RPM or +100RPM difference).


In effect, one signal determines how fast you move and the other determines how much you are turning.



I would expect the following:

Independent Unidirectional:
A control signal of 0% to 100% maps to 0% to 100% in only one direction.

Independent Bidirectional:
A control signal of 0% to 100% maps from 100% throttle CCW to 100% throttle CW, which would mean that a control signal of 50% is required to keep the motor at stand still.



Things get interesting when you turn mixing on.

In mixed bidirectional, I would expect a throttle signal of 50% keeps both motors at an average RPM of zero.

In mixed unidirectonal, I would expect a throttle of 0% to keep both motors with an average RPM of zero.

In mixed bidirectional, I would expect a differential signal of 50% to keep both motors turning in the same direction, if they are turning at all.

In mixed unidirectional mode it gets a bit fuzzy how the differential signal behaves. I am unsure whether a motor can actually reverse if you have zero speed on the throttle and change the differential. But it makes the most sense (and the manual seems to imply) that it can reverse allowing for a vehicle that can only go forward but truly turn on the spot.

Otherwise you have a vehicle that tries to spin around one static wheel when you try turn at zero speed. But it's possible the controller enforces the unidirectional setting that strongly.



The auxiliary inputs are on page 18. They are not the control inputs. They just allow you to tune sensitivity and rate of resposne on the control inputs.