Delta RMC101 - Manual (Page 585)

Quadrature with Analog Output 6.3
Transducer Interface Modules 6-41
6.3.7 Quadrature Scaling
Defining the Valid 16-bit Position Range
For general scaling information, see the Scaling Overview topic.
Because the RMC uses 16-bit positions, positions must all fit within a range of 65,536 position
units. Because position units are user definable, this range does not limit most applications. See
the section below on defining position units.
For quadrature axes, the Coordinate Limit parameter is used with the Scale parameter to define
the position range. If the Scale parameter is negative, then the position range extends from the
Coordinate Limit value minus 65535 up to the Coordinate Limit value. If the Scale parameter is
non-negative, then the position range extends from the Coordinate Limit value up to the
Coordinate Limit value plus 65535. The following chart summarizes this concept:
Scale Min. Position Max. Position
< 0 Coord. Limit -
65535 Coord. Limit
³ 0 Coord. Limit Coord. Limit +
65535
Other than using the sign of the scale, the Coordinate Limit parameter is independent of the scale
parameter. Therefore, it is recommended that you choose one of the following Coordinate Limit
values to allow you to use standard signed or unsigned position units. Other position ranges are
non-standard and take special treatment in PLCs:
Scale
Coordinate
Limit
Range Standard
< 0 65535 0 to
65535
Unsigned
< 0 32767 -32768
to
32767
Signed
³ 0 0 0 to
65535
Unsigned
³ 0 -32768 -32768
to
32767
Signed
Translating to Position Units
The translation of quadrature counts to position units is done incrementally. That is, the change in
quadrature counts is converted to a change in position units. These quantities are then added to
the current Counts and Actual Position status words. Therefore, only the Scale and the Prescale
Divisor bits are used in the conversion from Counts to Actual Position.
The following formula summarizes the translation from change in quadrature counts to the