How are digit values interpreted in an accuracy specification? i.e. "0.5% + 30d"

[cedd]

I'm comparing the accuracy specifications of various types of electrical readings for the Fluke 117 and the BM789. Fluke uses "counts" for its constant term while Brymen uses "digits". The specs are in the form of "Accuracy = ± ([% of Reading] + [Counts OR Digits])"

For example, when measuring millivolts in the 600mV range @ 45-500Hz, Fluke claims a "1% + 3 (counts)" accuracy. I interpret this to mean that for a voltage of 500mV, Fluke will show a reading of 494.7-505.3mV. Brymen on the other hand, when measuring 600mV @ 50-60Hz claims an accuracy of "0.5% + 30d". I don't know how to interpret the "30d" part and I haven't been able to find an explanation.

The specifications used in these examples can be found here:

Fluke 117 manual, page 20: https://www.instrumart.com/assets/fluke115_116_117_manual.pdf
Brymen BM789 manual, page 26: https://static.eleshop.nl/mage/media/downloads/BM789-5-manual-print1-r7.pdf

[PGPG]

For me digits and counts means here the same.
Fluke has 4 digits display while Brymen has 5 digits. So Brymen 30d practically means the same as Fluke 3 counts.

[cedd]

For me digits and counts means here the same.
Fluke has 4 digits display while Brymen has 5 digits. So Brymen 30d practically means the same as Fluke 3 counts.

Let's plug it into the example. Do you mean that a 500mV @ 50-60Hz input on the BM789, with +-(0.5% + 30d) accuracy, would give a reading of 494.5-505.5mV?

This is possible but what are you basing this opinion on that "counts" and "digits" are the same in this context?

[xrunner]

So Brymen 30d practically means the same as Fluke 3 counts.

At the top of the Brymen specs they say this -

General Specification
Display: 4-5/6 digits 60,000 counts.

So they use the term "counts" purposely. Not sure why they would later switch to using "d" in the accuracy specs.

[showman]

This is possible but what are you basing this opinion on that "counts" and "digits" are the same in this context?

Not an opinion. This is how all multimeter accuracy specs work. But if you don't believe us, here's an app note straight from the horse's mouth https://s3.amazonaws.com/download.flukecal.com/pub/literature/2547797_6203_ENG_B_W.PDF

[PGPG]

For me digits and counts means here the same.
Fluke has 4 digits display while Brymen has 5 digits. So Brymen 30d practically means the same as Fluke 3 counts.

Let's plug it into the example. Do you mean that a 500mV @ 50-60Hz input on the BM789, with +-(0.5% + 30d) accuracy, would give a reading of 494.5-505.5mV?

No!
You calculated it like specification would be saying 300d while it says only 30d.
Did you noticed in linked by you datasheet and in what I have written that Brymen has 5 digits (while Fuke has 4)?
Did you noticed what I have written that from that (5 digits display compared to 4 digits display) 30d is like 3c for Fluke (means is practically the same error value)?
So for 500mV:
- ideal reading is 500.00
- with 0.5% is 502.50
- with 30d is 502.80

This is possible but what are you basing this opinion on that "counts" and "digits" are the same in this context?

I just can't imagine different interpretation so I use the only one that fits in my head