Re: [CAD_CAM_EDM_DRO] Re: Chinese to Quadrature conversion

Peter Mack wrote:

>Thanks David,
>
>Unfortunately Mitutoyo use their own output which is unlike the common chinese output.
>
>Still looking. I know the process of reading and processing the output of the scales has been well and truly sorted out by many people, it's just the step of converting the numbers out of the Chinese device into quadrature output pulses that needs doing.
>
>To my limited knowledge of electronics and microprocessors this appears a pretty simple extra step. It surprises me it's so hard to find a previous example.
>
>

I think it might be kind of not-so-simple.

As far as I know, the output from the chinese scales is in a serial data
format, and it only gets updated a few times a second (maybe between 10
and 100 times). Each update contains the new position, which could be
many "steps" away from the previous position. So what the
microcontroller sees is position A, then A+delta. It then has to output
enough quadrature pulses to make the DRO display change by "delta". So
a question arises - how fast do you output those pulses?

You would need to have settings for input scaling (how big is a unit
from the sensor scale?), output scaling (how big is one encoder tick?),
and how fast the DRO can accept quadrature state changes.

It's doable for a specific scale/DRO combination, but I imagine a
product to do it would be more complex, since it would need to handle a
range of settings. (and of course I haven't even mentioned the math to
convert between units - it's not too hard, but it's not trivial in a
microcontroller either). And then you would have people who think they
could use this product for servo feedback (they can't). :)

- Steve