ACU-RITE 300S READOUTS - Manual (Page 19)

300S 5
I - 1 F
undamentals of P
o
sitioning
Encoder Reference Marks
Encoders normally contain one or more reference marks which the
300S Reference Mark Evaluation feature uses to re-establish datum
positions after a power interruption. There are two main options
available for reference marks; fixed and distance-coded.
Position Trac (Distance-coded reference marks): Encoders that have
marks separated by a specific encryption pattern allows the 300S to
use any two pair of marks along the length of the encoder to re-
establish the prior datums. This configuration means that the operator
only has to travel less than two inches any where along the encoder,
to re-establish the datums when the 300S is turned back on.
Fixed reference marks: Encoders that have one or more marks on
fixed intervals, have to re-establish the datums correctly. It is
necessary to use the same exact reference mark, during the
Reference Mark Evaluation routine, that was used when the datum
was first established.
The established datums’ cannot be restored from one
power cycle to the next if the reference marks were not
crossed before the datums were set