User`s manual

ProScale M150, M250 and all products with General Purpose LCD Digital Displays 8 of 44
Scales
Absolute
An (ABS) Absolute measuring technology system measures its actual position by reading
a pattern which is unique at any given location over a segment length. The maximum
length of a ProScale absolute segment is 430mm (16.932 in.). The segment must then
repeat.
Consider the illustration above to represent a ProScale approximately 50 inches long.
There are three absolute segments joined together. Within each segment the system is
absolute. However, crossing over a segment joint now presents the readhead with
information identical to what it read in the previous segment. At this point the system
must be able to recognize that it has crossed a joint and therefore must add or subtract
the value of 1 segment: 430mm. In fact, each time the readhead passes over a joint it
must keep track of how many segments it has passed, and in which direction. This
action is accomplished by the digital display and is transparent to the operator.
What does all this mean? If the readhead remains on the same absolute segment, it can
have power removed, its position changed and power restored without loss of position
information. However, if power is removed (readhead unplugged from Digital Display or
batteries removed from Digital Display) and the readhead passes over a segment joint,
the transition will not be recognized. When power is restored the system knows its
absolute position on the new segment, but does not know how many segments it has
passed, or in which direction. (Simply turning the digital display off does NOT constitute
removing power. A small amount of power is still supplied to the readhead; only the LCD
is turned off.)
General purpose digital displays provide the operator with a method to adjust the
segment offset so the system displays the correct reading at all times without loss of
accuracy.
See Section 4 for additional information on Segment Offset Adjustment.
All Absolute (ABS) scales have a “zigzag” pattern on a green laminate. Take care to not
damage the green coating. There should also be a pattern “SPLICE” approximately
every 430mm (17in.). To shorten (ABS) scales. Call Accurate Technology for
assistance, or visit: http://www.proscale.com/other/absscalecut.htm
Absolute (ABS) Style Pattern