THe scales are probably distance coded not straight quadrature.
Harko
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On 9/2/06, Jon Elson <elson@...> wrote:
mayfieldtm wrote:
Does anyone happen to know the signal format for Mitutoyo Linear
Scales, series AT715?
I want to interface one to a microcontroller such as a PIC and need
the pinout and signal information.
These scales are intended to be exclusively connected to Mitutoyos KA
Counters.
These scales are Absolute reading units and I'm assuming they spit out
a continuous stream of serial data to indicate current position.
Or they send data upon a request, or???
Probably they are just quadrature incremental encoders with a special
index
track. The way most of these work is that the number of quadrature
counts between
index marks is different between every pair of index marks. So, you
only need to
pass by any two adjacent index marks, and you know where you are. This
is the
simplest form of absolute encoder, and it takes no more electronics than
a standard
encoder with one index mark -- just 3 optical channels. A little bit of
software
in the readout box computes the absolute position. This requires a
small move
of the machine after turn-on before the absolute calibration is set.
Jon
