what means "GetRVelocity(Axis axis);"?

wafer

The GetRVelocity(Axis axis) method in the ACS.SPiiPlusNET library is used to retrieve the current velocity of the specified axis in real-world units (e.g. mm/s or m/s).

In motion control systems, the velocity of an axis is the rate of change of its position over time, and is typically measured in distance units per time units. The GetRVelocity() method retrieves the current velocity of the axis in real-world units by converting the internal velocity measurement used by the SPiiPlus motion controller (which is typically in encoder counts per second or motor revolutions per minute) into real-world units using the appropriate conversion factor.

Here is an example code snippet that demonstrates how to use the GetRVelocity() method to retrieve the current velocity of an axis in mm/s: