Points count on device - depend from device memory limits

Points count device can send to CPU on V2Plus4 not have limits (65536 only as uint16 value in settings) you can set any points count

V2 protocol (original) not allow get more then 255 measured points in one ask. So for get 1023 points need ask 255 + 255 + 255 + 255 + 3

In my firmware I allow write 0 at this register - and device return all points in one ask.

Thanks for the answer but I'm still confused.

Again, according to the manual ( https://nanorfe.com/nanovna-v2-user-manual.html ) the read command is 18-(AA)-(NN) where NN is a byte -- not uint16. Is this information out-of-date for V2Plus4?

What do you mean by "your firmware"? I'm using FW version 20220814, as listed in https://nanorfe.com/nanovna-versions.html.

Fefore read FIFO data, need set start freq, step, points by write in registers
00 - (qword) start frequency
10 - (qword) frequency step
20 - (word) points count
22 - (word) values pre frequency (need set to 1,

As can see points count is uint16_t value
After need read FIFO
0x18 0x30 NN

NN - read points count, yes this value is 8 bit

So if you set *1024* points before, need ask several times
0x18 0x30 *0xFF* read *255* points
0x18 0x30 *0xFF* read *255* points
0x18 0x30 *0xFF* read *255* points
0x18 0x30 *0x04* read *4* points
(255 + 255 + 255 + 4 = 1024)
This actual for your firmware version