HEIDENHAIN PWM 20 - Manual (Page 50)

November 2014 Software description 51
EnDat 2.2 status
display A yellow "Busy" symbol indicates access to the memory of the encoder EEPROM (12 ms max.)
Otherwise, the "Busy" LED is gray; it is used for forced dynamic sampling and for encoders with
functional safety.
The "Reference mark" LED shows whether the EIB has detected the reference mark signal.
(This function is only used in connection with the EIB interface converters.) If an EIB electronics
is connected and with incremental encoders, the LED is displayed in gray color and turns yellow
as soon as the reference mark has been traversed.
Note
The "Reference mark" LED of absolute encoders is always yellow.
For encoders without incremental signals the incremental status is masked out!
This status display is required for synchronization with the reference mark when using
HEIDENHAIN EIB interface electronics. Only after the reference mark was detected is the
incremental encoder "quasi-absolute".