HMO scopes: "maximum of 24,000 measured value points can only be read out"

[pxl]

Hi,

I am digging into the HMO manuals (HMO3000 series, HMO Series 72x...202x) and there is something I don't really understand. Under the "Documentation, Storage and Recall" part:

"10 .3 Curves In addition to references, you can also store A/D converter data. A maximum of 24,000 measured samples (expanded display memory) can be stored on a USB stick. Curves can only be stored to externally connected USB sticks (not internally).

The maximum of 24,000 measured value points can only be read out with the maximum sampling rate (ACQUIRE menu). For the AUTOMATIC setting (repeat rate), the maximum amount of measured value points is limited to 6,000 (default setting)."

Does it mean that only 24000 points of data can be saved only from the 2 MPts of memory? Or with the mentioned reference data, is it possible to save the full memory? If so, what is the saving Traces/Curves for?

[0xdeadbeef]

Yeah, I fear that is really a somewhat crippling limitation. It's hard to understand where this limitation comes from, maybe slow write speed?
Anyway, I understand that you need to use the USB connection to read out the complete buffer, but due to the limitation to 115200 Bits/s (VCOM), this also takes quite a while.

[gsocker]

Does it mean that only 24000 points of data can be saved only from the 2 MPts of memory? Or with the mentioned reference data, is it possible to save the full memory? If so, what is the saving Traces/Curves for?

I just gave this a try with my HMO3054 scope. There is an option in the trace save menu for display or acquisition memory - see the attached screenshot. At least when set to acquisition, it outputs the entire contents of the trace memory - 4MB with one channel active, or 2MB if both channels sharing the same interlaced pair of A-D converters are active.
With a single channel, the resulting CSV is ~104MB, and has 4,194,288 lines of values. The text/float/binary options are smaller.

Anyway, I understand that you need to use the USB connection to read out the complete buffer, but due to the limitation to 115200 Bits/s (VCOM), this also takes quite a while.

Mine supports USBTMC or VCP(VCOM), though I think this may depend on the interface card in the scope.

[pxl]

Ah, nice! Thank you, that's make more sense.

[0xdeadbeef]

Well, I fear this is different in the smaller models. At least in my HMO2024 the above menu looks different and there is no "Points" entry.
Actually I think these smaller models can't save their full memory to an USB stick and the 24000Pts limitation described in the manual is correct.