PLC Ethernet Integration

My question is: How to integrate Siemens S7 and an A&B SLC 500 over Ethernet TCP/IP ? Is it necessary to use a software driver on each device in order a TCP message (Industrial Ethernet x Ethernet/IP) be recognized by both devices ?

Yes the two PLC's both connect on Ethernet, but no, they do not share the same higher level protocols.

The simplest analogy is with a telephone, it is possible for both PLC's to establish a connection, but one is speaking English, the other German.

If you really need to do this then look around for a protocol bridge like the kind of thing ProSoft do:

A less expensive solution, but also less reliable and probably more complicated to get going:
Have A PC act as a gateway. You need:
RSLinx OEM OPC server.
Simatic NET OPC server.
OPC client middleware to act as gateway.

As explained by others, just having PLC's that can be connected to "ethernet" is not enough to have them talking to each other. A trend now is to use OPC, which is usually available for all new-ish PLC type devices. As mentioned, OPC is a PC standard which means you'll need to have a PC running this "bridge", and it naturally comes with the issues of PC (stability, Windoze itself, security, etc).

So the first question you need to ask yourself is: what do I want the PLC's to talk about?

If you are just relaying values from one to another that is not time dependent, or relaying commands/IO states that are not time dependent, bridging them via OPC is quite simple. But as soon as you want to do any time-dependent thing, like PID or real-time controls, you'll find it's starting to get sticky. Unless of course, you don't mind reaction times measuring in seconds (or ~0.5s).

If you can tell us what do you intend to do with the communication we may be able to offer more advice.