A few of our target systems returns absolute rubbish when performing a scan for instruments with viFindRsrs. The VISA version of one of them is 19.5.0f0.
I am using Pyvisa, which uses the search string '?*::INSTR' by default.
The returned list from viFindRsrs contains 38 hits, where only the first 6 are existing VISA addresses on the system:
('USB0::0x2A8D::0x9001::MY53240120::INSTR', 'ASRL1::INSTR', 'ASRL3::INSTR', 'GPIB0::8::INSTR', 'GPIB0::20::INSTR', 'GPIB0::26::INSTR', 'GPIB0::11::0::INSTR', 'GPIB0::13::0::INSTR', 'GPIB0::13::24::INSTR', 'GPIB0::14::INSTR', 'GPIB0::15::0::INSTR', 'GPIB0::17::0::INSTR', 'GPIB0::17::1::INSTR', 'GPIB0::17::INSTR', 'GPIB0::18::INSTR', 'GPIB0::19::0::INSTR', 'GPIB0::19::13::INSTR', 'GPIB0::19::23::INSTR', 'GPIB0::19::26::INSTR', 'GPIB0::1::0::INSTR', 'GPIB0::1::13::INSTR', 'GPIB0::1::17::INSTR', 'GPIB0::21::INSTR', 'GPIB0::25::0::INSTR', 'GPIB0::25::27::INSTR', 'GPIB0::25::30::INSTR', 'GPIB0::27::INSTR', 'GPIB0::2::26::INSTR', 'GPIB0::2::29::INSTR', 'GPIB0::2::30::INSTR', 'GPIB0::30::0::INSTR', 'GPIB0::30::13::INSTR', 'GPIB0::30::3::INSTR', 'GPIB0::30::8::INSTR', 'GPIB0::6::INSTR', 'USB0::0x05E6::0x2612::4041581::0::INSTR', 'USB0::0x0957::0x9002::MY50524003::0::INSTR', 'USB0::0x2A8D::0x9201::MY60440251::0::INSTR')
Interestingly, an IO-Trace of the scan looks perfectly normal, with only 6 found addresses, as expected.
I found a workaround by using the search string '/?*', which solves the issue (IO-Trace looks identical).
It seems this is a bug in the VISA drivers.