The Pro is available in two versions, the standard version and the -RW version. This page explains the differences.
There is, on the input to the standard controller, a noise decoupling circuit – a 100K resistor and a 1µ capacitor, giving a time constant of 100mS. This means that the slew rate (i.e. the accel and decel ramp rates) cannot exceed about 50v/second. With a 36v supply, that would mean about 720mS to reach full speed.
This capacitor was added only for some industrial applications where high noise levels into the controller occasionally caused a problem. In most applications it is simply not required, so it is omitted in the -RW version.
The ramp rate (zero to full speed) is adjustable, on the standard controller from about 330mS to about 7 seconds. This is not fast enough for some robots so the -RW version has ramps adjustable from 33mS to 700mS.
Diode feed ignition
Some roboteers like to hard-wire the ignition circuit. The standard Pro controller does not like that as it requires the main capacitor to be charged up before the ignition switch is made, or activation of the power relay is not certain.
In the -RW option, the relay powering is changed so the ignition may be hard wired. See the page Pro Controllers – ignition options for details.
Reverse dwell timing
In the relay circuit there is a timing capacitor to give a slight dwell at zero speed before reversing. This may safely be removed for robots!