Will have the results in a few minutes. In the meantime, the one you posted in #8 is not working. The bps is OK, but the rest is the same. Have tried with minimum rpm 1000 and also 8000, just in case... but the results are as before.
Edit:
OK, now tested this one as well. Sorry, but no champagne yet...
Multiple register writing mode:
Now it seems that polling starts and is going on normally as in the single register mode before, but the spindle speed sent remains zero, even though I configured the minimum to 1000 and also tested with 8000.
Single register writing mode:
Now even the frequency is sent, but only four zeros, so even here we still have a problem, probably the same.
BTW, I am using UCCNC 1.2032 but I should not think this is a problem.