It is not recommended that the GPIB address of the GSS4765 / GSS7765 ISG is changed as this will cause conflict with the hardware configuration file (sig_gen.txt) used by PosApp to determine which units should be available for testing and on which address. If you have a specific need to modify the GPIB address in order to use the ISG with the overall Spirent simulation system then please contact Spirent Applications Support with a copy of your sig_gen.txt file (found in the PosApp root directory = C:\Program Files\Spirent Communications\Positioning Application) and a brief explanation of your test requirements.
However, you may wish to change the GPIB address in order to temporarily use the ISG for other purposes. Since the ISG is an Agilent COTS unit, this is perfectly acceptable and can be done as follows (always change the address back before using the ISG with your simulation system once again):