S7-400H redundacy flow of data

Hello,

I have an issue with one S7-400H redundancy configuration. The redundant CPUs are connected via PROFIBUS DP to a redundant ET200M racks. The master CPU is connected with the left IM153-2 module of the ET200M rack and the slave is connected to the right IM153-2 of the same ET200M rack. The left IM153-2 seems to have some problem because the system detects that it cannot connect to it and transfered the active module to the right one. Although there isn't any error on the left IM153-2 module. My question is: How does the master CPU gets the information from the ET200M rack. Is it through the slave CPU or through the IM153-2 card. I am sending an attachment for better understanding of the problem.

Hi,

Option A

Hello,

Option B.

As  the active IM only come in action for data communication.

We mange to test it, so it is option B.

Regards,

Mehandzhiev

mehandzhiev

Hello,

I have an issue with one S7-400H redundancy configuration. The redundant CPUs are connected via PROFIBUS DP to a redundant ET200M racks. The master CPU is connected with the left IM153-2 module of the ET200M rack and the slave is connected to the right IM153-2 of the same ET200M rack. The left IM153-2 seems to have some problem because the system detects that it cannot connect to it and transfered the active module to the right one. Although there isn't any error on the left IM153-2 module. My question is: How does the master CPU gets the information from the ET200M rack. Is it through the slave CPU or through the IM153-2 card. I am sending an attachment for better understanding of the problem.

 Hello,

Siemens call your configuration a "Single-Channel Switched I/O configuration".

In your case, the CPUs are running in redundnat mode, and one of the slave is down. The I/O modules beside this slave can be reached to both CPUs through only One IM. The master CPU will remain master as nothong wrong happen in the master CPU will make it change its situation to slave or stop.

The master CPU will address the I/O modules through communication between the working slave IM and lisnk between both CPUs.

You can check my above explanation by check what will happen when power off or remove one IM from its rack. The second IM will be active and the I/O modules will be addressed by both CPUs.

Hope this helps.