[?]: Opinion for S7-300 or S7-400H

[Galli]

Dear friend.
I need opinion to do network PLC with Simplex or Redundant System.
The distance of the Remote I.O network is approximately 1.5 km to 2km to Central CPU ( S7-300 or S7-400, I have to decide ).
I have 5 Remote I.O Station ( I planned for ET200M ), each is 1.5km - 2.0km away from Central CPU.
Only simple Logix of Digital I.O and Analog I.O.
Any opinion for the best performance, and second reasonable price is very much appreciated.
Thank you in advance.

[CoMod]

in your case is more important than the type of processor, is a type of Network - an electrical or optical cable.
I recommend using an optical rings with OLM/G
http://support.automation.siemens.com/W ... n/19758281