Keysight Technologies M9300A Startup Manual page 21

While the M9300A module is being shared, any of the configurations that share this reference can control it
fully, including setting the reference to use an external frequency reference source. If the external frequency
reference setting does not match that of the supplied frequency, the reference will be unlocked, as expected.
However, only the instance of the SFP that creates the reference unlock condition can correct the problem.
This is done by either correcting the frequency or by setting the reference back to internal, so that a sub-
sequent instance will not take control of the reference module unintentionally.
The Reference module can also be shared among multiple measurement applications, such as the Keysight
89600 VSA software. The Reference module must be initialized before use, so including it in all configurations
allows applications to be started in any order. However, when sharing a module the user interface of some
applications may not reflect M9300A settings made by other applications. For example, the Keysight 89600
software can control the Reference module internal/external setting, but the changes made by other applic-
ations will not be reflected in the Keysight 89600.
FPGA updates are not allowed on a Keysight M9300A PXIe Frequency Reference while it is being shared. To per-
form M9300A FPGA updates, reserve the Reference.
Reserving the Reference for a Configuration
If you are running a test in the background with a certain M9300A setting and then connect a hardware con-
figuration that also contains the same M9300A, you may alter the test setup that is already running.
If you would prefer to be keep the reference control with the first instance of
the hardware configuration so that a subsequent instance will not take con-
trol of the reference module unintentionally:
1. On the SFP Connect to Instrument screen, click the Advanced control to open the
Options: dialog.
2. Type the following string: ShareReferenceVisaSession=0
This configuration will retain control of the M9300A if you try to open a new configuration. If you con-
nect a new configuration, that includes the same M9300A, you will see the following error:
If an existing instance of the SFP is connected to the reference module in a shared (default) mode, and you
try to connect a second instance of the SFP to the same reference with ShareRe-
ferenceVisaSession=0 Advanced Option, you will get the resource locked error shown above.
Keysight M9300A PXIe Frequency Reference Startup Guide
Step 4: Install the Module
21