Networking S7-200s

Hi, im a Uni student currently on work placement and have just started learning about PLCs.

I have been given the task to update a machine using an Allen Bradley PLC to a Siemens S7 200 system. With over 340 inputs and almost 200 outputs, it looks as though I will need to network some of the PLCs together - possibly 3 S7-226s with appropriate expansion cards.

From what I've read here and other places, I think what I need will be one master 226, the other 2 will be slaves. Using NETR i'll take all the inputs from the 2 slaves into the master and vice versa for the outputs.

What I'm not sure about is the network type I'll need - should I use Ethernet connection, thus requiring the adaptor, or is it possible to connect them together using the MPI/PPI interface?

Atm the Allen Bradley uses some interface (I cant remember which, sorry) for human interaction. I guess i'll also need to get a siemens HMI and program that instead of the old one?

I've been researching all this for the last few days, I think I am getting to grips with the whole concept eventually, I just need to know if I'm going about this the correct way.

Thankyou for your time.

Hello

I don´t know the Machine that you are talking, for me
it is esay for you used a S7-300 (S7-315-2DP)From siemens with DP Port
And used the Distribuid I/O technologie for example ET 200 S with a profibus network to pickup the signal from the machine.
I thing you have lot of I/o´s to used the s7-200.
Regards
Jose

hi Data..

I dont think you need any thing but the cable to communicate..or to establish a connec tion between all three of your PLCs...of course one plc(or two..you can have more than one master on the network) will be the master and use NETR/NETW instructions to exchange data...I reckon you will be reading the "I" and write to the "Q" memory locations..I am not sure what your application is...give more details..if you wanna get real help...

if you can show us what you have tried so far...we all can help.

hope this help.

regards.Khalil