you can do one thing you control the time at which you are writing,what i mean by this is say you want to write data every 2 min or when there is change in the output data,what you have to do is use a case structure over the write labview meas file.vi,start checking for the time change of 2 min or change in the output data using shift registers ,use a or gate so out put of the OR gate you can use with the case structure by this you willl have a control of the rate you are writing.
Hope it help else i shall post a example for you
vicky