what's wrong to make program terminated after long term run?

[hrwang]

I wrote a program to control 2 pumps, read one flowmeter, control a valve, and most importantly, turn on a heater by control how long a relay is on. Most of the controls were done in a while loop, and I set the loop time for 10s. I have tested the program for ~20hrs and the temperatures were monitored. It appears the program runs good in first 12hrs. The temperature reaches a steady state within probably 5hrs. Then there is a temperature drop after ~12hrs, apparently, something was wrong, either the heater was not working or the pump was not working (I set pump1 to work under a certain speed, pump2 at zero speed, valve was not open, flowmeter and pressure just reads a number). But the program still kept running for another hour, and next morning I saw a error message:

Error -50405 occurred at Heater PropContrl-sub.vi:Instance:3:1
Possible reason(s):

NI Platform Services: No transfer is in progress because the transfer was aborted by the client. The operation could not be completed as specified.

Task Name: _unnamedTask<59>

What could be wrong? Code is attached. It looks like the heater sub vi made the error. I also saw DAQ that reads the pressure was flashing after I stoped the program by closing the error message box, although I am not sure it was not performed properly or I have clicked by accident. Could be the memory was overwhelmed by the data? If so, how to clean the data? 

Thanks,

Haorong

[Tunde_S]

Hi hrwang,

What is the form factor for your DAQ hardware? If you are using a USB device, the explanation and solution that you need could be found here.