Please help identify this PLC setup

Hi there!

Im relatively new to the PLC world, I have some training in a  S7 1200 system and now I may have to deal with a new factory and their current setup

I visited it today.

They have 2 lines of PLC and modules.

Im attaching the pics I took. Please note that there are only 2 rails, some pictures are repeated with more detail in one side or the other.

I am able to identify:

Rail 1: 1-2= Power Supply. 3=CPU S400 414-2, 4=Profinet Interface 443-1, Rest= Digital In and Digital Out modules

Rail 2: 1,2=Power Supply; 3=ET200 IM153-1 Profbus Interface; 4=2 weighting modules Siwarex U; rest= Digital and Analog In/Out modules

Is all this right?Is there anything else you can find out from these pictures?

This factory is an animal food processing plant. They get different cereals (wheat, barley...), other nutrients and medicines, and prepare different mixes of flours to feed the animals at different stages. They have several motors to push the grain from silo to silo. Actuators to open and close gates, weighting scales to measure the amount of grain, etc

Can you guess what's the point of the profibus cable? Connecting rail 1 to rail 2? I see its going somewhere else, not sure where

Also to the right of this cabinet, there was a large cabinet full of relays, from the floor to the ceiling, probably 150 or more relays. Why wouldn't they use relay output modules and use external relays?

And the HMI you see in the other picture too.

Any help you could provide will help me understand the current setup in this factory

Thanks in advance!

Rail 1 is a S7-400:

The article number is under the top screw. You have to put "6ES7" in front.
Example: The CPU on place 3 (CPU 414-2) is 6ES7414-2XG03-0AB0

Rail 2 ia a S7-300 ET200M:
The article number is on the bottom. You have to put "6ES7" in front.

Enter the article number in the online support and select manual to find the manual of this modules.

You can see the PROFIBUS calbe and the ET200M modul just as an extention of rail1
For the CPU program it makes no difference if a io-card is located central (rail1) or decentral.(rail2)

I saw only 32 DOs in your pictures. With this DOs you can't control 150 relais.

Why they use relais?

• The current a DO cord can switch maybe too small?
• Maybe th DO card and an external relay is cheaper then a RO card?
• "protection" of the PLC?

So is there a CPU in the rail 2? My understanding is that only rail 1 has a CPU (S7-400) and rail 2 is like a slave chain of inputs and outputs connected by profibus, isn't this the case?

Putting together all the outputs in both rails (maybe not all were shown in the pictures) there should be above 100-150 individual bit outputs, my guess is they all go to the external relays to drive them

If I were to design this circuit I would have used relayed outputs instead of 24V outputs + external relays but Im not an expert on this.

Thanks

Ok now this is more alike to what I was expecting, thanks a lot

If I am ever requested to modify the programming on this PLC, my guess is that the old provider has the sources for the current program and he may not want to share it with me. Will I be able to recover the source code from the PLC itself?

Thanks