Connecting I/O modules on 2 racks

Hello everyone,

i would like to know if there is any way to connect 2 different racks, without adding any special module. The problem is bcus of cabinet's wideness, ET200S (IM151) CPU can accept up to 63 modules including power. I am talking about Siemens. On 1st rack i can add only 27 I/O modules and need to continue on 2nd rack which is below the 1st one. So my question is if it is possible to connect last I/O module to 1st module of 2nd rack? If is, please lead me to right way how to do it. Plus if I need to add additional module to connect them, which one should i choose?

Thanks a lot.

I am guessing you are meaning the IM151-8 CPU.
No you cannot extend an ET200S rack from the "end".
The IM151-8 has Profinet on board, so you setup the next rack as a Profinet IO Device.
The next rack should start with an IM151-3 Profinet IM, and then you add ET200S PM and i/o modules as in the 1st rack.
You connect the expansion rack to one of the PN ports in the IM151-8 CPU.

CPU is IM151-7, thanks for answer. I wasnt sure if is possible w/o module, thought there is some kind of cable bcus distance between last io module and beggining of next rail is 20cm...

btw. i have cpu 315 DP as master, and now I need to extend i/o modules but dont have enough space to add them in series, so its in need to add additional rail, thats why i asked for help. i was sure that is possible the way u wrote.

Thanks.

Errr...

I am not sure what you want to do.
Add another ET200S rack as an expansion to the Im151-7 (this is impossible).
Or keep the IM151-7 and its ET200S IO and add another ET200S rack as an expansion to the 315-2DP.
Or replace the IM151-7 as CPU by the 315-2 DP, and then have the original ET200S rack plus another ET200S rack as expansion racks for the 315-2DP.

I would replace the IM151-7 for an IM151-8 and add the expansion racks via IM151-3.
The big advantage is that you get Profinet.

Well I have already CPU 315-2DP as master in main cabinet. In other cabinet I have IM151-7 connected to master CPU via profibus. I need to add 54 I/O modules on IM151-7, but on 1st rail I have free slot for only 27. So I need to put other 27 I/O on additional rail. How should I connect them?

I used wrong word up there, sorry. its rail not rack xD

An IM151-7 is a PLC with its own program. If you need the functionality of a distributed PLC with its own program, but connected to a master PLC, and the available space is already used up, and it must be expanded, then with the current hardware you have an impossible situation.
The IM151-7 is only intended to be used as an "intelligent" distibuted IO station. It cannot be expanded.

The only solution I see is to replace the IM151-8, and then you also have to replace the 315-2DP for a 315-2PN/DP.
That, or something else in the preconditions described above have to change.

A maybe unwanted comment:
If this is a new installation (less than 10 years old), then it is poor decision to base it on Profibus. The limitations are as you have found. And Profibus is generally slowly becoming osolete.

The only way I know how to do it would involve a special module.

You can add a DP Master interface (6ES7 138-4HA00-0AB0) to your IM151-7, and then add a second ET200S rack with a profibus interface module IM151-1. This creates a second DP network. Your IM151-7 would be a slave to the 315, and then the second IO rack would be a slave to the IM151-7.

mk42, you are entirely right.
I was too early when I said it was impossible with the current hardware.
The only thing is that the DP master module costs around 40 mm extra width in the existing ET200S rack.

JesperMP said:

The only thing is that the DP master module costs around 40 mm extra width in the existing ET200S rack.

Click to expand...

Agreed, he may need to shift a couple modules into the new rack. Hopefully he left enough slack on the wires....