Introduction
If the duration of the outage is shorter than the power supply filtering time, it has no effect on the program which continues to run normally.
If the duration of the outage is longer than the power supply filtering time, the program is interrupted and power restoration processing is activated. The CPU then restarts in warm restart or cold start as described in the following diagram.
Illustration
Power cycle phases:
Power Supply Filtering Times
The BMX CPS 2000, BMX CPS 3500, and BMX CPS 3540T power supplies, which provide Vac power, have a filtering time of 10 ms.
The BMX CPS 2010 and BMX CPS 3020 power supplies, which provide Vdc power, have a filtering time of 1 ms.
Power Outage Processing Phases
When power to the system is lost, it recovers in 3 phases:
Phase |
Description |
|---|---|
1 |
On power outage, the system saves the application context, the values of application variables, and the state of the system on internal flash memory. |
2 |
The system sets all the outputs into fallback state (state defined in configuration). |
3 |
On power restoral, some actions and checks are done to verify if warm restart is available:
If all checks are correct a warm restart is performed, otherwise a cold start is carried out. |