LabVIEW
get date time string in RT
The two clocks are unrelated. Windows synchronises with the web, but the RT system does not.
You'll have to make your own time synchronisation, or use SNTP, or GPS.
To do it yourself, first you need to get the time from the PC, then you can set the clock (Set Time.vi). You can also set the time from MAX (to ensure that that is the problem). But the clock will drift, since the CPU's clock speed is never exactly as specified. So if the system is on for long periods, you need to synchronise clocks.
I'd prefer SNTP, since it is a provem method, and involves less work.
Search LabVIEW like a graph! 
I also recommended SNTP, and not doing it yourself.
The nice thing about SNTP is that it's handling the time syncronisation problem at the core. It adjusts CPU speed, and you'll never come close to the results if you do the corrections from LabVIEW. I'm not sure if NI-Timesync does that, I've not used it.
I have set my PC time zone to UTC 5:30 but still dint catch the fault.
That is because the cRIO clock does not synchronise with the PC clock.
Matt's point is (or implies) that even if the clocks are synchronised (with SNTP, NI-Timesync, or manually in MAX), the time you read will still be off when the time zone of the PC and the cRIO are different. The synchronisation will synchronise UTC, and the time you read will (unless you set UTC flag) give you the time zone corrected time. I'd try to work with UTC in all code, and only correct when absolutelly needed. Over here we have automatic daylight correction, and that makes non-UTC even harder.
So you need to fix both problems.
