hp53131A frequency from both channels

[John_Y1]

I am measuring 2 frequencies, using both channels of an HP 53131A, connected via GPIB / USB to LabView 7.  I need to control trigger level, filter on one channel, gate time etc
I can do this and get both numbers by using a while loop to set up channel 1, read frequency, set up channel 2, read frequency, set up channel 1 etc etc.  This is a bit slow, approc 3 to 4 seconds per cycle, with a gate time of 0.8 seconds.  It seems that there must be a way of setting up the channels once and then putting the read commands only in a loop. 
I have tried READ (@1) , READ (@2) but it doesn't work, READ only reads the most recently set up channel.  Any ideas?

Yes, I have also tried two separate counters, with two VISA/GPIB addresses through the same interface - gives cycle time of ~1 second ie only slightly longer than the gate time.
Just slightly overkill though!

[Dennis_Knutson]

The setups for both channels only need to be done once but there is still going be be some time required to switch back and forth between two channels. I'm going from memory here as I don't have the manual but you can do it manually by using the CONF command to select channel 1, then doing an INITiate, and then a fetch. Repeat for channel 2. Or, the MEAS:whatever? @1 followed by a MEAS:whatever? @2 will work as well. As far as I know, you cannot setup the instrument to be continually measuring on two separate channels. You have to do the switch and when you do the switch, you have to start it counting with the INIT.

p.s. Even though you have a counter, the Counter/Timer forum is supposed to be for NI's Counter/Timer product line. Next time, post in the instrument control forum, please.

Message Edited by Dennis Knutson on 04-02-2007 07:50 PM