Adding Control Logix I/O rack

Probably a rather basic question, I'm just getting started in my transition to ControlLogix from PLC5s and SLC/500s....

We have a project coming up to do modifications to an existing system which consists of a 1756-L61 Processor in a completely full 17 slot I/O rack. We're going to need to add another rack in a new panel located about 20 feet away from the existing one.

What's going to be the easiest way to add the additional I/O? What hardware is it going to take? The existing rack has a Devicenet module (1756-DNB) which is talking to several VFDs - is that going to be of use?

Have you already got an Ethernet module in the rack?

Can you change it for an 1756-EN2T?

If not, assuming that remote racks will be on Ethernet, and not ControlNet, then an Ethernet card will need to be added and another card taken out...

Main thing is that the remote racks should be in a different network from your PLC-PLC-SCADA communication network.

PLC5s had the Ethernet port plus the RIO port and DH+ port.

Apparently the "new" 8 series ControlLogix processors will have built in Ethernet port(s)

John, I think I was updating my post to indicate that the existing rack has a Devicenet module at the same time you were typing.

Anyway, there's a 1756-ENBT ethernet module, but that's used to talk to the HMI and is also connected to the building network. I'm not sure I want to put I/O on that card.

Also, if we need to add another card we'll be able to consolidate some I/O onto existing cards and free up one slot.

How much additional IO do you need?
That is the first question.

I'd just go ahead and drop a PointI/O rack on Devicenet personally, additional racks as needed.

Yes, I am about to start planning some PLC5 upgrades and will need to look at the communication detail.
We have devicenet scanners on some 1771 racks and controlnet PLC5 in some cases.

I know that there are different Ethernet cards for ControlLogix, but have not yet used the dual port nor redundant ones..

Aye, catching up with posts here, devicenet can be used for Point I/O, Flex I/O maybe even ControlLogix I/O...depending on your needs.