Thank You for library, I use it with my Siglent scope and signal generator devices. Found that sometime on openDefaultRM VISA can return not only VI_SUCCESS, but VI_WARN_CONFIG_NLOADED which is not error, just warning. After this visaResourceManagerHandle is zero and openInstrument don't work correctly. Proposed fix: public long openDefaultResourceManager() { try { LOGGER.info("Open resource manager."); pViSession = new NativeLongByReference(); VisaLibrary.ViStatus visaStatus = visaLib.viOpenDefaultRM(pViSession);...