4 System
4.7 Licensing
4.7.4.1 Application Licenses
Application Licenses (like N9077EM0E-1NP) are automatically checked out when
entering the Mode that uses them, and they are automatically checked-in when
leaving that Mode. Because the server may have already checked out the last
license for the application to another instrument, there is now the possibility that a
mode switch will fail because a required license could not be checked out from the
server. If the server has a limited number of licenses compared to the number of
users desiring to use that license, this may mean that switching from Mode A to
Mode B then back to Mode A may fail when returning to Mode A because another
instrument checked out the last available license while the user was in Mode B.
Also, for Modes with multiple licenses for different features (like Multi-Standard
Radio), the features available may also change when switching out of the Mode and
back into it.
So, when using network licenses, it is necessary to check :SYST:ERR? after every
Mode switch, to verify that it successfully switched. If the Mode’s required licenses
were not successfully checked out, the instrument posts the error:
-310,"System error; feature not licensed"
There is also a potential performance issue when using network licenses, because
the instrument must communicate with the server on each license check-out and
check-in. This operation is usually fast (a few milliseconds), but it depends on the
network communication lag between the instrument and server. For remote servers
on slow or congested networks, this could be significantly slower than that.
4.7.4.2 Instrument Software Options
Instrument software licenses are those that are reported via *OPT? the same as HW
options. For example, N9040RT1B-1NP is an instrument software option, and is
reported via *OPT? as RT1. Note that the license is composed of the model number
(in this case N9040B) combined with the option code (RT1).
When instrument software options are available from a network server, the
instrument automatically checks them out at start-up, and only checks them in
when shutting down.
4.7.4.3 License Checked Out Query (Remote Query Only)
Shows whether the specified license is checked out from a server. Since network
served licenses may not always be available when there are limited licenses
available compared to the desired number of users, the features available on an
instrument can vary. Use this query to see whether the feature is currently checked-
out to the instrument. The return value is boolean (0 or 1), returning 1 if the feature
Spectrum Analyzer Mode User's &Programmer's Reference 2180
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