Switch doesn't show any log when AC is put in back.

Question

I'm using two kind of switches i.e Cat2960S-24TD-L and Cat2960S-48TS-L with RPS2300 for backup power.
One question was raising in my head during the power redundancy test on the switches.
My question is how NMS can recognize that AC power is put in back as normal status without any log.
Each switch has two power sources. One from AC built-in power and the other from RPS2300 as below.
Access_SW#show env all
FAN is OK
TEMPERATURE is OK
Temperature Value: 39 Degree Celsius
Temperature State: GREEN
Yellow Threshold : 50 Degree Celsius
Red Threshold    : 60 Degree Celsius
SW  PID                 Serial#     Status           Sys Pwr  PoE Pwr  Watts
1  Built-in                                         Good
2  Built-in                                         Good
SW  Status          RPS Name          RPS Serial#  RPS Port#
1   Active          RPS1              FDO1447YGT3  3
2   Active          RPS1              FDO1447YGT3  6
~snipped~
DCOut  State   Connected  Priority  BackingUp  WillBackup  Portname        SW#
    1       Active  No                6            No         Yes         <>                -
    2       Active  No                6            No         Yes         <>                -
    3       Active  Yes               6            No         Yes         Access_SW         1
    4       Active  No                6            No         Yes         <>                -
    5       Active  No                6            No         Yes         <>                -
    6       Active  Yes               6            No         Yes         Access_SW         2
When I pull out the AC power cable out from the switch, it shows the proper log saying as below.
Access_SW#
Jul  8 17:15:46 UTC: %PLATFORM_ENV-1-PWR: Internal power supply not supplying power (Access_SW-2)
Access_SW#show env all 
FAN is OK
TEMPERATURE is OK
Temperature Value: 39 Degree Celsius
Temperature State: GREEN
Yellow Threshold : 50 Degree Celsius
Red Threshold    : 60 Degree Celsius
SW  PID                 Serial#     Status           Sys Pwr  PoE Pwr  Watts
1  Built-in                                         Good
2  Built-in                                         Unavail
SW  Status          RPS Name          RPS Serial#  RPS Port#
1   Active          RPS1             FDO1447YGT3  3
2   Active          RPS1              FDO1447YGT3  6
~snipped~
DCOut  State   Connected  Priority  BackingUp  WillBackup  Portname        SW#
    1       Active  No                6            No         Yes         <>                -
    2       Active  No                6            No         Yes         <>                -
    3       Active  Yes               6            No         Yes         Access_SW         1
    4       Active  No                6            No         Yes         <>                -
    5       Active  No                6            No         Yes         <>                -
    6       Active  Yes               6            Yes        Yes         Access_SW         2
But I put AC power cable back into the switch, it doesn't show any log and any change to me. It still shows 'Built-in is Unavail' as below.
Access_SW#show env all
~snipped~
SW  PID                 Serial#     Status           Sys Pwr  PoE Pwr  Watts
1  Built-in                                         Good
2  Built-in                                         Unavail
SW  Status          RPS Name          RPS Serial#  RPS Port#
1   Active          RPS1              FDO1447YGT3  3
2   Active          RPS1              FDO1447YGT3  6
~snipped~
DCOut  State   Connected  Priority  BackingUp  WillBackup  Portname        SW#
    1  Active  No                6  No         Yes         <>                -
    2  Active  No                6  No         Yes         <>                -
    3  Active  Yes               6  No         Yes         Access_SW         1
    4  Active  No                6  No         Yes         <>                -
    5  Active  No                6  No         Yes         <>                -
    6  Active  Yes               6  Yes        Yes         Access_SW         2
The problem is how the operator can decide 'Now AC power is okay so I will push the button on RPS to make it backup again' without getting any information from the switch.

Answer 1

Hi innetee9228:
If the output of "show env all" doesn't change when you put the AC power back in, that's indicating a bigger problem.  You see the %PLATFORM_ENV-1-PWR: message go when the power comes out, so there should be one when the power goes back.  That's more indicative of an IOS problem where the status isn't getting updated as it should. 
The SNMP agent rides along side the guts of the IOS that feed the SHOW commands.  If the hardware isn't reporting correctly or whatever and "show env all" doesn't tell the truth, it's not likely that the SNMP agent is going to be receiving truth, either. 
Once you have that addressed, you should be able to turn up power supply event traps and send them to whatever SNMP Manager you'd like, and have that alert your operator.
nms-6506-e(config)#snmp-server enable traps envmon supply ?
  fan          Enable SNMP envmon fan traps
  shutdown     Enable SNMP environmental monitor shutdown traps
  status       Enable SNMP environmental status change traps
  temperature  Enable SNMP environmental monitor temperature traps
nms-6506-e(config)#