Hi Didier, Sending ++addr 23 (the address of my 3478A), locks up my prologix until it is disconnected from the 3478A. Here is how I tell: ++ver [Prologix GPIB <-> USB Converter Version 5.0] ++addr 23 ++ver [the silence is deafening!] ++read 10 [the slience is deafening!] ... pull the prologix off of the bus... ++ver [Prologix GPIB <-> USB Converter Version 5.0] ... we're back! ... -Chuck Harris Didier Juges wrote: > Chuck, > > Sending > ++addr 09; > ++read 10; > with my Prologix to the HP 3478A returns a single reading just fine. > > Didier KO4BB