Remote I/O v Distributed I/O
I don't have time to get into great detail right now on the subject matter, but I'd just like to make a passing comment or two on what I've read so far.
Bit_Bucket_07 is quite correct, if the OP is asking what they appear to be asking.
The OP referred to Local v Remote I/O for a ControlLogix. So we would be talking 1756-RIO or 1756-DHRIO modules. Remote I/O is quite slow by today's standards. It is most definitely slower at communicating with the controller than Local I/O in the chassis. These modules are primarily used for applications where it is necessary to communicate with older equipment and so they are chosen more out of necessity than for their throughput.
The references to "todays" or "newer" communications networking transport methods, such as Ethernet, or the like, are not relevant here, if indeed the OP meant Remote I/O proper, and not the category which Ethernet, or the like, do fall under - namely Distributed I/O.
So either the OP and some of you guys are mixing these two terms up, or the OP knows what they are asking, and it's just some of you guys that are mixing them up?
If it's a case of the former, then proceed to discuss Distributed I/O as you were.
If the latter, then it's a much narrower discussion.
Either way, I thought it important to make that distinction.
Regards,
George