The first two RS232-to-USB cables that I bought didn't communicate very well, which was not a big problem since I could program the Fuji PXG4 by hand and use the Amprobe for measurements and logging with Artisan.
Marko Luther from Artisan advised me to look for a cable with a more modern chipset, like the FTDI. Yesterday I found what looked to be the right cable at Farnell and today UPS delivered it:
|Red line: target (=PID SV), black line: bean temp, bottom right LCD: percentage of heater power used by PID|
|The full graph, note the black line mostly overlapping the target line|
|Resulting roast, two different origins, some color difference too|