DeviceNet verse Profibus


Thread Starter


A project is looking at using serial comms for interconnection between the control system and the MCC control gear. There are 33 MCC rooms with approximalty 1300 drives of which about 300 are to have VSD's, max 200 drives in an MCC. Which is the best solution DN or PB ??



On a project that apparently involves at least $500K (probably a lot more) in MCCs and their contents, I'd open up my options and pay a consultant for an architecture, not a network recommendation.

I would not confabulate serial and networked comms, then confabulate 1300 of something (drives) and 300 of apparently the same thing (VSDs), in a post to an Internet list.

For the record, to the extent I understand your problem at all, I would use one or more Ethernets, and might use DeviceNet or ProfiBus or something else for subsystems, depending on a lot of factors not given in your post.

Hope this helps!

Larry Lawver
Rexel / Central Florida

Yosef Feigenbaum

The major issue that you'll have with your installation is the number of devices that you'll have to connect to each network. Device net is limited to 64 (actually 63) Profibus has more than 100, if I'm not mistaking (124?, someone correct me if I'm wrong). This means that you'll have fewer networks to handle.

If you are doing control over these networks then you should stick with the DN/Profibus solution. If the networks are monitoring, I'd consider Modbus which allows 247 nodes.

Good Luck,

(8{)} ( .)
[email protected]

The most important factor is "what protocol is supported by your VSD and Contactor supplier." In my recent book, "Automation Network Selection" (ISA Press), I point out the decision for the network is usually dependent upon
the network supported by your major electrical supplier. It is rare to select the network first. In this case, Profibus/PROFInet and the combination of DeviceNet/EtherNet/IP would be equivalent in functionality
and cost. Modbus/Modbus/TCP is also an available solution.

Dick Caro
Richard H. Caro, CEO
CMC Associates
2 Beth Circle, Acton, MA 01720
Tel: +1.978.635.9449 Mobile: +1.978.764.4728
Fax: +1.978.246.1270
E-mail: [email protected]
Buy my new book Automation Network Selection

James Ingraham

That depends on who you ask. Allen-Bradley has a very nice system for MCCs using DeviceNet. Siemens, of course, wants you to use Profibus. Are you ordering the MCC panels pre-built, or are you building it from components? If they're pre-built, your vendor probably has a preference and you might as well just go with it.

Of course, Profibus will only do 127 nodes on a network, and DeviceNet does a mere 64. So this is gonna be a big system by any standard. Leverage the expertise of the people involved in the project. What do your vendors like? Do you have an in-house guy who knows one or the other? What's in the rest of the plant?

The technical merits of the two aren't really that important; six of one, half a dozen of the other.

-James Ingraham
Sage Automation, Inc.
That depends on your controller, Paul. If you're using Siemens, go Profibus. If you're using Rockwell, go DeviceNet.

I've commissioned a lot of DeviceNet MCCs, usually with some sort of ControlNet or Ethernet/DNet bridge in an MCC bucket as the scanner.

I like DeviceNet on drives; it's easy to upload and download parameters, and having the reference signal be digital is a huge wiring and troubleshooting benefit.

You're going to have to segment up your system, anyhow; DeviceNet only supports 64 nodes, and Profibus 127 per network. The practical limit is about half that in each case.
There are a lot of ifs in this question, but to open the door.

The drives you are talking about are contactors right, so here you probably want to turn the contactors on/off and read the overload and or circuit breakers here you use about 1000 to 2000 digital inputs and 1000 outputs without any bells and whistles.

The VSDrives need based on the brand and type either a adapter witch may determine the network you want to use, or analog and digital I/O.

Both networks have their pros. and cons. And it all depends on the distance, data update speed, etc. You might even want to look at Ethernet/IP because you can handle 254 nodes or more on 100Mbs and the distance is no problem because you can use standard fiber optic and components.

I really need a little more info to give you a reasonable answer. If you want to you can contact me because I used a lot of different networks and all of them have their good and bad sides.

Carel Colpa
[email protected]

Bob Peterson

I would tend to agree that if you are stuck going one way or the other, it does not really matter much which one you choose. I am a bit nervous about the AB Devicenet starters having heard so many horror stories about them.

My inclination is that drives are a good choice for such bus control and motor starters are not.

Bob Peterson
If this is true, then it should be possible to use AS-i in combination with profibus or devicenet according to the documentation i've been reading an AS-I network master should be able to connect 124 inputs and 124 outputs. devices each capable of supporting. an AS-I gateway uses only one node from an profibus or devicenet.the choice between profibus and devicenet is then simplyfied by looking at what the best choice is for the VSDrives.

i must admit that most of my knowledge is based on documentation, so if i'm interpretating this documentation wrong, please tell me


Bart Visser

Steve Myres, PE

> That depends on your controller, Paul. If you're using Siemens, go Profibus. If you're using Rockwell, go DeviceNet.

I'll concur with Ken except to say that if you're using Siemens, go Profibus, but if you're using AB, go Profibus (SST Modules)! ;-)

I did an application with a SLC-5/05 with a SST Profibus scanner using Automation Direct DL205 series I/O with a Profibus comms adaptor, and the speed was phenomenal.

Steve Myres, PE
Automation Solutions
(480) 813-1145