I have a problem with the behaviour of a CPU 416-3 PN/DP.

INTRODUCTION :

After START-UP, CPU S7-400 does not reestablish automatically communication with Profinet Slave ( ET200M) because it has lost the SYSTEM DATA.

PROBLEM:

Let me explain the particular problem I have,

I have 2 simple configurations:

1.     1.

S7-S7-300 with one Profinet SLAVE ET200M and I/O Modules associated.

All configured with the default values.

Download of the project standard.

Communication between S7-300 and Profinet Slave ET200M is working perfectly

Now , I power off the S7-300.

The BF led of ET200M starts blinking; obviously, it has lost the communication with the master.

Then, I power on the S7-300.

The BF stops blinking immediately. Communication works without problems.

 2.

2.       S7-400 with one Profinet SLAVE ET200M and I/O Modules associated.

(exactly the same than before but the CPU is S7-400 instead of S7-300).

All configured with the default values.

Download of the project standard.

Now , I power off the S7-400.

The BF led of ET200M starts blinking; obviously, it has lost the communication with the master.

Then, I power on the S7-400.

The BF does not stop blinking.

In the Hardware Configuration I go online appears a prompt telling me:

-          Differences ONLINE/Offline

Cause : System Data Differs.

The only solution to put this ET200 Slave back online is reloading the SYSTEM DATA, and to do that I must download the project again.

Once the CPU gets  ‘system Data’ again the communication starts.

Why the ‘416-3 PN/DP’ is losing the system data during the POWER OFF ?

How to solve it ?

As always , thanks in advance.

Sorry Folks,

It was a simple problem of batteries.

I replaced the batteries from the PS and now it works fine

The System Data lost in two ways 

 if the batteries died or the power supply damaged.

As I understand from your problem you do not have problem in batteries....

You should check the communication nodes which you have in your application 

The problem will be obvious more if you make a print screen of your Topology 

Hi Jordi,

a question: was there any entry in the diagnostic buffer?

For checking the battery and generate an alarm I do like the following FAQ´s - I think this could help you.

https://support.industry.siemens.com/cs/de/en/view/42002283

and

https://support.industry.siemens.com/cs/de/en/view/11499205

Regards,

Towome