LINEPULS & LINECOD catalogue 2016 in English

LINEPULS • LINECOD
Sottotitolo Technical information
Linear encoders can be incremental or absolute.
Incremental linear encoders produce square waves signals or sinusoidal signals and can
provide travel, position and displacement information. Positional information is cyclical,
thus relative and ambiguous; this means that you can gather whether the axis is moving
and the direction of the movement; yet you cannot get information about its absolute position.
To compensate for this glitch the homing operation is always required at the beginning
of the process to determine the absolute position of the system (detection of the zero point;
then it requires counting of cycles to maintain absolute position within the travel range).
For such reason most incremental linear encoders can produce Index and/or Reference mark
pulses providing a datum position along the tape for use at power-up or following a loss of
power. For detailed information on incremental linear encoders refer to page 24.
Incremental encoder
An absolute linear encoder is designed to output the absolute position information in
response to motion along a linear path. It relies on a unique code pattern encoded on the
tape, so it can provide a unique and unambiguous position within the travel range without
requiring knowledge of any previous position. The major advantage is that you can always
gather exactly the position of the axis. For instance, in case of power loss or failure, then at
power-up the absolute encoder will be able to output the current position of the axis precisely.
This means that no homing operation is required to determine the current position.
An absolute encoder provides the motion controller with either analogue signals or a digital
code information. The digital information can be in pure Binary or Gray code format.
Customarily the absolute encoder encompasses serial (SSI, BiSS) output circuits, but it can
also afford analogue and fieldbus interfaces.
For detailed information on absolute linear encoders refer to page 34.
Absolute encoder
At a glance: Linear Encoder typical features
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