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3.5 Diagnostics
3.5.1 Absolute-to-incremental deviation
Note
Display and functions may vary depending on the product key and the connected encoder!
With the function "Comparison of absolute and incremental values" absolute encoders can be
checked for the following defects:
Code transition errors between absolute and incremental values
Scale contamination and resulting signal and position errors
Signal interferences (interference problems with resulting positioning errors)
Internal propagation and calculation times etc. may cause a difference between the absolute and
the incremental position values.
Note
The absolute value is calculated at the scanning point (scanning unit or electronics of rotary
encoder) and is serially transferred to the PWM 20 or IK 215 as absolute data word.
The incremental signals are transferred to the subsequent electronics via the analog
interface and are processed there (interpolated, digitized).
In the test unit the absolute and the incremental position values are compared to each other
and the difference is displayed as deviation span.
The different signal paths (propagation times, calculations, etc.) result in a deviation
between the absolute and the incremental position display; the deviations must not exceed
the specified accuracy ranges.
Deviation span and accuracy (displayed in LSBs) are defined for different velocity ranges.
Attention
The absolute value of the deviation span must not exceed the specified accuracy of the
velocity range.
The deviation span is displayed in red color, if the tolerance is exceeded.
March 2011 Software Description 71