What Happens When the CompactRIO CMOS Battery Dies?

Updated Oct 21, 2020

Issue Details

If I reboot my cRIO after the CMOS battery has failed, what would happen to my cRIO?
  • Does it reset all the information and configurations?

Solution

Once the CMOS battery is dead, the cRIO will lose track of its current time, including the date. It will revert to 12:00:00 AM, Jan 1, 1970 and will start counting seconds from there.
The date/time can be updated on the cRIO through NI-MAX or through application software, but it will again be lost once power is cut off.

Additional Information

The CMOS battery only powers the real-time clock on the cRIO and it does it only when the cRIO is not under power. When the cRIO is powered, the real-time clock gets its power from the external source rather than the battery. Nevertheless, there is some leakage current so eventually the battery will drain even when powered externally.
No other subsystems of the cRIO are powered by the CMOS battery, so no other functions will be affected in the event of a dead battery.

There is no way to check the remaining battery life. The only indicator is when it fully drains and time is lost on reboot.

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