BNC 577 - Manual (Page 30)

Model 577 Operating Manual 24
8.5.8 Error Codes
The 577 responds to all commands with either:
ok or ?n
Where "n" is one of the following error codes:
1 Incorrect prefix, i.e. no colon or * to start command.
2 Missing command keyword.
3 Invalid command keyword.
4 Missing parameter.
5 Invalid parameter.
6 Query only, command needs a question mark.
7 Invalid query, command does not have a query form.
8 Command unavailable in current system state.
9 Parameter out of bounds for the given module.