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BOSCH
Flexible Automation
Description Stage 4 Chapter 2
CC
lOOM
User
Manual
Revolution-coded,
Incremental
rotary
encoder
(Messrs. Stegmann)
Basic mode
of
operation:
The difference
with
respect to a conventional incremental encoder lies
in
the additional absolute
disks which
are
subordinate
to
the incremental
disk..
The counted pulses of
the
disks are supplied
to
a control logic within the encoder.
This control logic,
at
a defined count,
now
inserts an additional pulse (marker) per revolution, in
addition
to
the reference pulse, dependent upon
the
number of revolutions.
This point is offset
by
one more division period each revolution. On the basis
of
the distance
between the
two
markers,
it
is
possible
to
determine the absolute position, referred to
the
encoder zero point The absolute position, referred to a displacement, is determined
by
induding
an
offset which must
be
determined during commissioning. Once the absolute position
has
been
determined, the encoder is handled
in
the same way as an incremental rotary encoder.
No special position is required when installing the rotary encoder. There is
no
need for mechanical
adjustment, as on conventional encoders. Different encoders can
be
connected unrestrictedly to
one system: e.g. incremental encoder for
the X axis, revolution-coded, rotary encoder for the Z
axis.
Umltatlon
by
the
encoder:
The traverse path is limited by the encoder. The maximum path in pulses results from the maximum
number
of
countable revolutions of the encoder
and
the numbers
of
lines on the encoder x factor
4 (see also Machine parameters).
Determining the absolute position:
By
contrast with conventional incremental rotary encoders, traversing
to
a ·reference point
cam-, followed by synchronization, is
not
required when determining the absolute position.
The operating software of the
CC 100 determines the absolute position within one encoder
revolution.
Advantages
of
the revolutlon-coded Incremental encoder:
o Simplification and shortening of the reference pOint approach procedure since the absolute
position can be determined accurate
to the increment after a maximum of 1 encoder revolution.
o Reference point switches are
not
required,
and
neither are wiring, adjustment
or
matching etc.
o Extended measuring system monitoring thanks
to
plausibility check
of
the revolutions
signalled cyclically by the encoder.
o The revolution-coded incremental encoder can take the place of any standard incremental
encoder (same interface, cables etc.).
2-10
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