Confusion over DMM "4.5 digit resolution" for DMM

[John]

Thanks guys!
It makes a LOT more sense now.

John

 

[David L. Jones]

On Nov 7, 11:03 am, John <jmuc...@SPAMMENOTcamlight.com> wrote:

I'm confused. I thought that a "4.5-digit resolution" DMM meant that
it went up to "19999" (with decimal point appearing somewhere).

But, I've been considering stepping up to the Agilent U1252A DMM and
though it's advertised as "The Agilent U1250A series handheld digital
multimeter gives you 4.5 digit resolution with a 50,000 count full
scale in dual display with high contrast blue backlighting.", it has a
full 5-digit display in the photos and the specs later on in the data
sheet say "Both primary and secondary displays are 5 digit on the LCD
display."

So what is limited to 4.5 digits?

The term "4.5 digit" is a marketing throwback to earlier times, some
people still expect to see the term "4.5 digit resolution" used. The
unit is 50,000 counts, and that's all you need to know. It's better
than an older "20000 count" "4.5 digit" meter.
For readings under 20000 count (say 1.5V), the two meters give you the
same resolution, but if you are measuring something between 20000
count and 50000 count (say 2.5V), then the 50000 count meter gives you
an extra digit of resolution. Likewise, for readings above 50000 count
(say 7.5V), bother meters will give you the same resolution.

There are also meters that can give you 10000 (9999) or 100000 (99999)
count. In this case if you measured say 7.5V you'd get an extra digit
resolution over the 50000 count meter.

Dave.

 

[Phil Allison]

"John"

I'm confused. I thought that a "4.5-digit resolution" DMM meant that
it went up to "19999" (with decimal point appearing somewhere).

But, I've been considering stepping up to the Agilent U1252A DMM and
though it's advertised as "The Agilent U1250A series handheld digital
multimeter gives you 4.5 digit resolution with a 50,000 count full
scale in dual display with high contrast blue backlighting.", it has a
full 5-digit display in the photos and the specs later on in the data
sheet say "Both primary and secondary displays are 5 digit on the LCD
display."

So what is limited to 4.5 digits?

** The "resolution" - which is the smallest increment of change that can
be displayed on a given range.

Eg: If the meter is set to the 5 volt DC range, the resolution is 0.1 mV.

It would still be 0.1mV on a 20,000 count display, when the range is 2
volt DC.



........ Phil

 

[DJ Delorie]

John <jmuchow@SPAMMENOTcamlight.com> writes:

So what is limited to 4.5 digits?

My guess is that you need a full seven segments to display "0" and
"2", but the measurement range is limited to (say) 4.9999 before it
changes to 05.000. My multimeter is like that - it has four full
digits, but only displays up to 3.999 before bumping up the scale.
(it may display 0.xxx hence the full digit)

Hmmm... maybe it makes the meter more "stable" at readings near powers
of 10 (0.1, 1.0, 10.0) as it won't keep trying to change scales due to
tiny variations in the readings?

 

[Anthony Fremont]

John wrote:

I'm confused. I thought that a "4.5-digit resolution" DMM meant that
it went up to "19999" (with decimal point appearing somewhere).

But, I've been considering stepping up to the Agilent U1252A DMM and
though it's advertised as "The Agilent U1250A series handheld digital
multimeter gives you 4.5 digit resolution with a 50,000 count full
scale in dual display with high contrast blue backlighting.", it has a
full 5-digit display in the photos and the specs later on in the data
sheet say "Both primary and secondary displays are 5 digit on the LCD
display."

So what is limited to 4.5 digits?

You said "the count" was 50,000. That usually means you will see numbers up
to 49999 in the display.

 

[Jamie]

John wrote:

I'm confused. I thought that a "4.5-digit resolution" DMM meant that
it went up to "19999" (with decimal point appearing somewhere).

But, I've been considering stepping up to the Agilent U1252A DMM and
though it's advertised as "The Agilent U1250A series handheld digital
multimeter gives you 4.5 digit resolution with a 50,000 count full
scale in dual display with high contrast blue backlighting.", it has a
full 5-digit display in the photos and the specs later on in the data
sheet say "Both primary and secondary displays are 5 digit on the LCD
display."

So what is limited to 4.5 digits?
Thanks!

John
I would guess it might be the +/- symbols on the left.

--
"I'm never wrong, once i thought i was, but was mistaken"
Real Programmers Do things like this.
http://webpages.charter.net/jamie_5

 

[John]

I'm confused. I thought that a "4.5-digit resolution" DMM meant that
it went up to "19999" (with decimal point appearing somewhere).

But, I've been considering stepping up to the Agilent U1252A DMM and
though it's advertised as "The Agilent U1250A series handheld digital
multimeter gives you 4.5 digit resolution with a 50,000 count full
scale in dual display with high contrast blue backlighting.", it has a
full 5-digit display in the photos and the specs later on in the data
sheet say "Both primary and secondary displays are 5 digit on the LCD
display."

So what is limited to 4.5 digits?
Thanks!

John