Activate the rear-panel TRANS-Z INPUT connector.
10 OUTPUT 723;"XAMPSW ON;"
The XAMPSW command allows input via the rear-panel TRANS-Z INPUT connector. Normally, the output of the optical spectrum analyzer's internal photodetector connects to a transimpedance amplier. Using the ON argument switches the amplier's input from the photodetector to the rear-panel TRANS-Z INPUT connector.
The maximum current allowed at the rear-panel TRANS-Z INPUT connector is 610 mA and the maximum input voltage is 610V.