MPIRatio
Declaration
typedef struct MPIRatio { long numerator; long denominator; } MPIRatio;
Required Header: stdmpi.h
Change History: Added in 04.00.
Description
MPIRatio is used to set a ratio. The ratio is used for feedback scaling. It is programmed into the firmware by using a numerator and a denominator, where numerator/denominator = ratio. All 32bit values are valid, however, the values should be the smallest integers possible that will give the desired ratio. This allows for the highest velocity attainable using a ratioed feedback value.
WARNING!
Do not configure the Numerator x Maximum Actual Velocity (counts per sample) to be greater than +/2,147,483,647 (31 bits). If the motor's Actual Velocity exceeds +/2,147,483,647 (counts per sample) / A, the Actual Velocity value will rollover to a negative value, causing erratic servo motor control. This condition could cause the motor to runaway, potentially resulting in damage to equipment or injury.
To disable the encoder ratio calculation in the controller, set numerator and denominator to zero. If your application does not need an encoder ratio, set numerator and denominator to zero for optimal controller performance.
Notes:
Do not configure the motor encoder ratio while the amp is enabled.

Do not set numerator/denominator = 1 because it is equivalent to disabling this functionality while consuming more controller resources.
For an example of how to configure this parameter, please refer to the encRatio.c sample application.
Controller firmware with the Encoder Ratio build option is required to use this feature. To determine if your controller firmware supports this feature, check the Firmware Features Table.
numerator  The numerator. Default value is zero. 

denominator  The denominator. Default value is zero. 
See Also
MPIAxisGearConfig  MPIMotorFeedback  mpiMotorFeedbackRatio