Type the onpload -f flags

When you combine -f flags into one group, do not put spaces between the flags. For example, use -f acq.

If you prefer, you can use multiple occurrences of the -f option instead of combining all of the possible -f flags into one group. For example, the following two command lines are equivalent:
onpload -m mymap -d mydev -flnc

onpload -m mymap -d mydev -fl -fn -fc