Timing/ data retrieval issues with USB-GPIB controlled instrument, HELP!

[Khume]

Hi, I am trying to operate an SRS SR400 photon counter using LabView 7. I have an optical chopper as the external trigger and I am using both channels A and B in a gated way.
Basically I can get the photon counter to operate perfectly being controlled by LabView, but if I collect only one data point at a time in Labview, the data displayed is that recorded on the photon counter 7 counts previously. If I ask LabView to record say ten counts, I generally get 9 of the same number repeated (the same number which appeared on the SR400 7 counts previously) and then a random 0 or 6, like it is trying to pull data from an empty buffer, or when there is no data being sent. I am using a new NI USB-GPIB card to interface the PC and SR400, which I have not used before, we have always used the PCI cards, so I do not know if it is due to the USB interface or my code. Ultimately I would really like LabView to display the most recent value recorded in the photon counter, and be able to do that for as many counts as I want. I am sure the problem lies in some buffering or handhsaking issue, but I'm relatively new to LabView and can't figure it out. Any help will be greatly appreciated! The code I'm using is attached
Thanks!

	AllThatStuff.vi (76 kb)
	SR400 Read_e2.vi (130 kb)

Message Edited by Khume on 05-01-2008 12:22 PM

[MXI Master]

Duplicate post

Please only post in one forum. We monitor all the forums so their is no need to post in different threads. All are monitored very frequently. If you are unsure of which thread to post in, don't worry we will find it no matter where you post. In this instance the appropriate board is the  Instrument Control (GPIB, Serial, VISA, IVI) board, where I answered your question.


Message Edited by MXI Master on 05-02-2008 10:36 AM