I am using Siemens 414-3 CPU. One time CPU goes to stop and all LEDs were blinking. I reset it but still all LEDs were blinking. I looked to the documentation, it says "CPU Defective". What kind of reason is there for it? Is there any idea?

After I changed CPU with new one, I get out the defective CPU from rack (program deleted), and I gave energy in my lab. CPU was looking good.

I could not understand what happened.

 

Hello ykirca;

Just from my experience:
S7-400 CPUs flash all LEDs to induicate a major fault, either a CPU or memory malfunction, or a shortcircuit on the backplane (power or data buses).

The S7-400 rack uses a top-pivot insertion method for the modules, that is you start by "hanging" the module at the top of the rack and then push it in to the backplane in an down-arcing motion. I have had occasions when if this is not done with care, some backplane pins are forced out of position by the incoming module, causing short-circuits in the backplane and forcing the CPU to flash all LEDs.

I have saved myself a few (very long) troubleshooting trips by requesting that the local techician remove the modules one by one (starting with the power supply module, then the CPU...), check all backplane pins on the rack with a flashlight to look for bent or touching pins; generally it solved the problem. Of course the technician always found it strange that any pin shoud be bent, as they NEVER(!) remove and reset any module by themselves, while under power...

If your CPU is now working well outside of the original rack, this might be one cause of your problems.

Hope this helps,
Daniel Chartier

 

Something if the hardware configuration is wrong, it would stop the CPU. When getting modules from the Hardware Catalog, make sure the part no. is correct.

 

Here also same problem faced.

all LED are blinking 2 times in a second on S7 416- 2PN CPU.

Any have diagnosis or fault identification manual for S7 400 CPU then inform me? then send me a need to know how and with which reason same problem occur. as because of that problem my whole process got down and really get unsafe conditions of process.