That's what I did and it works fine but I want to start and stop the instruments from another instrument. I can' seem to be able to do this. You made the point off list that I can use pvsbuffer for this type of thing and it works well too. The main problem now is that if I start more than 10 or so pvs instruments I get drop outs due to the relatively slow machine I'm using! I'll have to wait till I get to work on Monday to try it out on something more powerful. Rory. 2008/12/6 victor : > This example shows what is possible... > > > > instr 1 >