Differences between DeltaV (Emerson) & ControlLogix (Rockwell)

I have to choose one of mentioned systems for my project (linear station of a pipeline) which has almost 400 physical I/Os. can you please help me comparing these two systems in terms of realibility, robustness, applications, performance, cost, after sales services, etc.?
DeltaV is a DCS, ControlLogix is a PLC.

ARC Advisory Group is surveying readers on LinkedIN at this link:
and appropriately, DeltaV appears in the list, ControlLogix does not, but A-B's PlantPAx does appear in the list.

There are distinct hardware/software architectural differences between a high end PLC and a DCS.

In my opinion, you left out a critical criterion - support, short and long term, which tends to be VERY local to your area.

And when you ask such a broad question, I'll assume you (your company) is not implementing it, which means the systems integration is as important as the capital purchase of hardware/software.

Interview integrators and ask what they'd recommend and why. Yes, they have their favorites, but I suspect they'll be the ones doing the programming and commissioning.
Thanks a bunch David_2 for your reply...

Actually I didn't get the right point out of it. Although you are right about DCS & PLC systems, at the first layer they can be assumed both as PLCs since they include controllers, I/O modules, etc. to control a small station. Besides, they will be connected to a central SCADA point in the future.

I'm looking for your kind reply on that again.

David Ferguson

I have used both.......first comments have said one is a dcs one a Plc....first of all I laugh at this ignorance (no slam meant, if you don't know you don't know).

I have done this for 30 years and have witnessed the snobbish DCS is better than Plc debate for years.......neither Delta V not Rockwell PAx (with Controllogix) are Plcs not DCSs.......they are the modern transition of control systems commonly referred to as a PAC.......Emerson bought a controller and Intelution HMI and tied it to (at the time) PI for a historian.......Rockwell took Controllogix, FT View, RSlinx, Pi and their marketing dept came up with a name PAx and built blocks for functions etc of a control system.

My opinion of the two..........Emerson carried over their DCS model from Provox and kept the license model.......we paid a ton in license fees and the software worked great but customization took a deeper level.

Rockwell could do all of the things I had ever done with a DCS......my DCS experience was with Provox and Foxboro and I have done Rockwell PLC code and HMI for 30 years....

My Opinion is Rockwell for the following reasons.

1. Backward compatibility, Rockwell has always maintained backward compatibility so I can connect to old 1771 IO and old devices still today......now that doesn't mean they won't kill that. But in my 30 year career, they haven't so assumption is you won't. A lot of Emerson stuff and others......you throw out everything and start over when moving.....while they provide steps to move from Provox to DeltaV, Rockwell does a better job.

2. With the lack of personnel......it is easier in most industries to find Rockwell expertise than DeltaV although in the oil industry Emerson has a leg up....although Control magazines category winner for the top 50 different categories has been Rockwell for years.....has this means is a broader compatibility. I can teach shift electricians to use Rockwell easier than DeltaV for the most part.

If I need to add drives......or motion control, or simple bang bang (PLC code) it's all there because they cover so many industries.

I have also found that the "openness" of the Rockwell PAx blocks lets me add any strange functionality I may run into.

Both are very good, Emerson has been in the "process" game longer, but generally has bought their technology lately. Rockwell has set its sights on being large in this sector and is making huge strides, has always been a major hardware maker, is in a lot of other sectors, drives motion etc.....I think generally Emerson's support is better, Rockwell's is ok.

I could go on for a long time......again the two major systems I had at my job before retiring and worked with every day were these two.....I still consult on the side and will only do Rockwell work at this stage, because I find a better toolset and better flexibility but everyone is different.

This is only my opinion.....

Dave Ferguson
Senior Control Systems Engineer, CAP, CCST
Although modern DCS and PLC controllers, I/O and front end hardware have the same price point, the DCS has proprietary software, server and point licensing requirements.

So depending on what HMI, SCADA and historian you use and want to integrate this new pump station into; that will determine your PLC vs DCS decision.

I suspect that a Rockwell ControlLogix system will integrate with less additional hardware and software costs.

good luck
I have to choose one of mentioned systems for my project (linear station of a pipeline) which has almost 400 physical I/Os. can you please help me comparing these two systems in terms of realibility, robustness, applications, performance, cost, after sales services, etc.?
Almost entirely dependent on the application. One is not better than the other, but one may be better than the other for your application. Even then, there is functionality overlap between the two. I did a LARGE project that, when first designed, was almost all discrete control. My personal preference for discrete control is Rockwell. As the project went on, a lot of analog was added. If I knew that ahead of time, I might have chosen DeltaV but the project was already about 25% coded. Rockwell handled the change in controls just fine, but DeltaV might have been a better solution (easier).
Now that almost all communication is done with ethernet rather than proprietary protocols and with Rockwell's PlantPax systems, it makes less of a difference in choosing in my opinion.