Re: Cheap DRO system using digital scales and a PC

That's interesting!! It describes very closely the flow I observed.
You may want to use some 74HC595 or similar shift registers and
a RC clearing circuit after a portion of the dead time between
data bursts. This will greatly ease the software overhead.

I'll keep playing with it, unfortunatly I have a software deadline
and vacation next week, so it may be awhile.

Thanks,
-Lee


--- In CAD_CAM_EDM_DRO@egroups.com, "Wilfried Fedtke"
<wilfried.fedtke@t...> wrote:

> Hello,
>
> i try to connect my digital scale with the computer. My digital

scale

> looks like that of http://www.guanglu.com.cn/Digital%20Height%

20Gage%

> 20&%20Scale%20Unit.htm.
> I have gotten following description to my digital scale:
>
> Working of the interface: synchronus serial
> Data: Binary code, 24 bits, each datum will send twice
> The cycle is 300 ms (or 20 ms in fast reading state)
> transmitting time 0,5 ms
> Pulse range of data: Datum level <=0,2 V , level "1" >= 1,3 V
> Clock pulse: CP 90 kHz, effective for high power level
> wires: negative power, clock pulse, data, positive power.
>
> To be read the data over the serial interface, it is very difficult
> since the data-transfer takes place synchronized.
> I want to try to read the data over the parallel interface.
>
> Another problem is that the signal is very high-ohm-y (correct
> english??). I tried the aticle of Lee
> http://www.users.qwest.net/~indigo_red/files/calip /, thank you,

but

> my digital scale has negative impulses.
> I exchanged the npn transistor with a pnp transitor and I got
> positive impulses. Now I want to try as next to decode the signals
> via parallel interface and visual basic...
>
> Under http://www.guanglu.com.cn/Vernier%20Series.htm you can see a
> plug.
>
>
> Wilfried
>
> http://members.xoom.com/rchobby/fraese/start2.htm