One way is a USB-I2C adapter wired to the ADC converter and reading
through LinuxCNC HALUI.
Although I haven't investigated further. Need to check the details.
If you'd have the device doing the 0-10V / 4-20 mA output that'd work
although there needs
calibration due to resistor voltage bridge required to drop the Voltage
to that of the ADC.
Jean-François
Le 07/03/2022 à 21:34, Thaddeus Waldner a écrit :
Acuity sells what I need brand new for $1000.
Keyence appears to be a much more common brand, given by the number of eBay
items.
These are not time-of-flight devices; they work instead by measuring the
position of an angled laser spot on the target.
I’m looking at the Keyence IA-065. The working range of 2.17" - 4.13” would work for
my application. I’m a bit puzzled by the “linearity" spec on the data sheet. It
reads as follows:
+- 0.1% of F.S (F.S.=+-10 mm 0.39”, 55 to 75mm 2.17 to 2.95”)
I read that as within the range of 55mm to 75mm, the linearity will be within
0.2% of that range, which comes to 0.04mm or about 0.0016”. Is my logic and
math correct?
Second question, what is the simplest (and cheapest!) way to get this analog
voltage into LinuxCNC. I do have a couple of 24-bit I2C devices on hand
(ADS1220). Is this workable without writing a driver or something like that?
On Mar 7, 2022, at 2:01 PM, gene heskett <ghesk...@shentel.net> wrote:
On Monday, 7 March 2022 12:44:21 EST Thaddeus Waldner wrote:
Hi,
I’m looking for a laser distance sensor with about 1-3 thousandths
resolution and about a 5-10” working range. I wouldn’t mind buying a
used unit.
1. I didn't know they came in that high a resolution w/o needing a quorum
of the US Senate to authorize the payment, then signed by the President.
If you want to know why, calculate the time difference of that 3
thousandths of an inch increment, remembering that it has to travel out,
and back to the measuring device, equal to C/2 in speed. You will I
suspect will come up with a very small fraction of a picosecond.
Interferometry can measure that change, but the mod function to detect
the individual null and count it has to start at zero, or a known micron
sized distance before it can count the nulls passing by as it moves from
zip distance, back to your point of interest at a 12" max range. Moving
slow enough to count, will take a 2048 bit counter and several days.
Technically, we can do it but you'll need a couple of dump trucks full of
gold to finance one neasurement. We can't yet buy a calibrated answer in
10 milliseconds for a $500 bill. Someday? Maybe, but it may take a new
method to be invented.
Does anyone here know of some brands/ models to check out?
Google has pointed me at some Acuity products but I wondered if there
were other options besides that.
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Cheers, Gene Heskett.
--
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author, 1940)
If we desire respect for the law, we must first make the law respectable.
- Louis D. Brandeis
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