For some reason, my Siglent SDG1025 was once found by pyvisa, but now is not being found by pyvisa using rm.list_resources(). AHA. It looks like it just takes awhile to boot up. I now see the instrument listed as USB0::0xF4ED::0xEE3A::SDG10GA3163315::INSTR The read termination appears to be rn and the write termination is just n. It is now responding to my queries.