Starrett/ Mitutoyo SPC protocol conversion

"Lee Studley" <indigo_red@...> wrote:

> Doug,
> I think all of the 6 signals are described in the .PDF diagram at the
> link you listed. All you have to do is figure which is which.
> http://www.matronics.com/cncscale/index.htm

Actually, no. That setup is for SPC, some sort of serial ascii/binary
output. The six pins there are 1-GND, 2-Transmit,3-Send(clock?)
4-NC, 5-NC, 6-NC

According to Matt Dralle dralle@...
The Mitutoyo SPC stream is: "thirteen 4-bit digits", and mysteriously
the binary bits are sent in reverse order: 1000 means 1 and 0001 means 8
-d1 = 0xF = 1111
-d2 = 0xF = 1111
-d3 = 0xF = 1111
-d4 = 0xF = 1111
-d5 = sign + is 0 (ie 0000( - is 8 (ie 0001)
-d6-d11 = digits
-d12 = decimal point location 0x2 mean xxxxx.xx etc
-d13 = units mm is 0 (ie 0000) inch is 1: (ie 1000)

Also according to Matt, the Starrett SPC data stream consists of 25
ascii characters (sent at 1200 baud, 8 bits (8th bit masked), no parity,
and 2 stop bits).

1-13 = ascii spaces (0x20)
14 = space if positive, minus sign "-" (0x2D) if negative
15-21 = ascii digits representing current reading, including a floating
point decimal "." (0x2C)
22 - space
23-24 = current unitin ascii inches = "in" millimeters = "mm"
25 = carriage return (0x0D)


Doug Fortune