problems on periodic instruments controlling

[oahchao]

hi, all, I'm new to Labview. I'm now facing some problems on instruments control.

Now I'm doing a project need to control 2 instruments automatically. one of the instruments(Instrument 1) need to be ON for 65 mins and OFF/Reset for 35 mins. the other instrument(instrument 2) need to be reconfigured every minute based on its own output, for example, one of the cases is i need constant power, so every minute, i use DAQ to get its output voltage, and then reconfig its current settings. and the problems I'm facing are:

1. I can use a while loop to control instrument 2 for a short period of time, but after some time, there will be an error message" the data which is previous avilable now has been overwritten." and suggest me to increase the buffer size. but basically i dunt need any buffer, i just using dynamic data to reconfig the instrument every minute, where could cause this problem?

2. can anyone give me some suggestions on how to control instrument 1? i tried use square wave signal to control, but it not works.

any help will be appreciated. Thanks a lot.