Both Pro and Con
I've commissioned hundreds of AC drives on Ethernet, and many hundreds on DeviceNet. A few dozen on ControlNet. Maybe ten on Profibus DP.
I agree that the Logix 5000 v16 interface with EtherNet/IP and AC drives is top-notch, and by far the easiest interface to use on any platform. I generally default to using EtherNet/IP for I/O chassis and operator interfaces.
DeviceNet is still my strong preference for power controls.
DNet's cheaper per adapter than higher-level networks. It's predictable. It's nearly noiseproof. It's easy to install, especially in MCCs, if you're not an absolute hollering moron.
With PowerFlex 7-series drives, whose interfaces support Change-Of-State I/O connections, DeviceNet is pretty fast (about a millisecond per node). Less so with drives that only support Polled I/O, which is most third party stuff.
The 1756-DNB gives you a strong suite of diagnostic tags, provides simple messaging from the controller to the drive, and supports runtime editing of the scanlist. The new DNet Tag Generator Utility makes usage of UDTs much easier than in the past.
EtherNet/IP has, in my opinion, three major things going for it.
It's a powerful and easy interface in RSLogix 5000. Very powerful. Very, very easy. I/O chassis, PanelView terminals, and AC drives are easier to use with RSLogix 5000 on Ethernet than any other network.
Getting online with drives is faster than any other network, for uploading and downloading and monitoring.
The built-in HTTP server in most devices is useful for quick-and-dirty monitoring.
But EtherNet/IP has some downsides, and believe me I've seen them all.
The first is that there's a pervasive idea that Ethernet should be cheap. Switches cost eighty bucks at Fry's.... why would I buy an expensive managed one ?
It's just not the case. Properly installed, Ethernet costs as much as ControlNet or Profibus, and more than DeviceNet. If you buy unmanaged switches you are intentionally putting an undiagnosable weak spot at the heart of your control system.
And you're going to need those diagnostics if you build anything serious. During your time with the system you absolutely are going to have a miswired cable or a loose connector or a noisy link and you're going to have a hell of a time tracking it down because you don't know where to look, and it generally repairs itself so fast you can't tell when it's broken unless you aggressively monitor the I/O connections in Logix.
I have a customer fighting his third-year campaign against a big system with non-RA drives on Ethernet. He's got noise problems, no doubt. But he put in an architecture of cheap switches with no management or diagnostics and I just can't help him solve the problem without going out there myself with a hub and an analyzer and a thousand dollars a day purchase order. He swore at RA for the first year, then at his drive vendor the second year (four firmware upgrades) and then at Fate the third year. I think they're just living with the nuisance trips now.
If you ever get your installation contractor telling you that they have "never had noise problems" with Cat5e cable, keep shopping for a more experienced installation contractor. We've seen about everything: installations with Cat5e cables run parallel or wrapped around 120/240/480 VAC lines or in the conduit with drive output cables or five hundred feet tied to the rafters of a steel mill, or split into two half-duplex circuits to use existing cables.
The two devices that come with me on every sales call that involves networking are the 1788-EN2DN network bridge, and my NTron 7014TX heavy-caliber managed switch.
