Also, use QGNSS and its ‘advance’ button to calculate the NMEA checksum. Then just enter commands complete with a * at the end. I have a running scratch pad of commands in a doc that help me do some low level config tests. Also, remember that you often have the do a save and unit reset for any given command to take effect (it’s annoyingly about 50% of the time, NMEA message enable no, RTCM message enable yes).
