Further to my ask above, look up SI0, scan time, when online. You will likely find that it will indicate that the 190 can relate to the input being counted every scan. ie scan time might be 5ms, say. On 5ms that's 200 scans/sec, but SI0 rounds things a bit, so you can see my point re 190.
But Joe, you would not believe the huge price difference in Aus on those things. Greed coupled with hopeless service can be a nasty/frustrating thing to deal with. I often whinge that I can get the same components from a quicker responding, more diligent overseas supplier at way less price than I can get locally, including the high shipping cost from o/s, and they often arrive quicker as well.
"Use our online form to do an order" Ring to check on no response a day later. "Ohhh, that doesn't work properly, send me your stuff to my direct email" is what I hear a lot locally. It can take a week just to arrive at a final invoice. All under the guise of "our prices are higher because we have so many overheads". Bollocks. More like "money for nothing", and useless at that.
I know I've gone a bit off topic. End of rant.
I think the clue about the span of values is here:
15 bits : 0.61uA/Bit(0~20mA), 0.49uA/Bit(4~20mA)
The uA per bit is different depending on the range.
I think that the mention of the sign bit is superfluous (and therefore confusing) as the module only has unipolar inputs.
I think experienced Unitronics users are conditioned to expect a 4...20mA analogue range to not use the full span of the digtal word, based on experience with other Unitronics families. But as Flex has commented some Vision modules (mainly outputs) will use the full digital scale regardless of whether they are 0...20mA or 4...20mA.