Both run and stop LEDs blinking together.

Hi Everyone,

I am working on siemens s7-412-5h Redundant system. problem is that, sometimes when i download my modified program then master cpu comes in run mode as usual but standby cpu is not coming in run mode and starts blinking both run and stop LED together.

Hello paresh_ramdya,

please be so kind and don't post twice or more for the same problem.
Thanks.

You post also here (second reply):

https://support.industry.siemens.com/tf/ww/en/posts/steps-to-indicate-the-led-status-of-cpu-412-5h/131922/?page=0&pageSize=10

Dear paresh_ramdya,

Are you able to open the module information of the PLC? the Rack 1 PLC. Look for the "Stack" tab. It can show you what is stopping the plc from booting up. 

But i guess you cant open the module information. Normally I caused by something wrong with programming. Memory reset the second CPU, (PLC->Clear/reset, or manually force reset at local) , then turn on the CPU again and download the CPU again. 

Check your modified program, any special DB/FB/SFB you have override, you can also restore back the previous working one to study the behaviour. 

Hope it is helpful for you