How can I control two instruments simultaneously

[G]

Hi, I want to control two instruments ( 2400 and a 6487 ) at the same time. I have them both sourcing and measuring voltage/currents in a sequence but they follow each other. What I really need to do is i.e. set the 6487 at a constant bias 2V, then the 2400 to do a IV sweep, then move onto a bias of 3v in the next sequence. Any help on this topic would be great,

Thanks Gethin

[Dennis_Knutson]

Communication of GPIB is sequential in nature. You address one instrument, send a command, address a different instrument, send a different command, etc. To make simultaneous measurements, you need instruments that support triggering. This could be either an external signal that will tell each device to take a measurement when the signal is detected, or a GPIB bus trigger. This is usually done by commanding a GET (Group Execute Trigger) command. In either case, the instruments are sequentially armed for the specific trigger type and then they wait for the trigger to arrive before taking the measurement. You would then sequentially query each instrument for the measured value. I used a 2400 a long time ago and I think it supported both types of triggers. I've never used a 6487 so you'll have to check the instrument manual to what support it has.