Control.com - Nerds in Control

I am implementing motor controls in a new treatment plant that consists of a variety of VFDs, soft starters, and across the line starters. Since this is a new plant, I am considering using ethernet to communicate with my VFDs and soft starters, rather than the digital and analog PLC I/O that I typically incorporate.

I am concerned about the reliability and the operation using Ethernet for motor control I/O, as it seems to me that I have heard of drives dumping gobs of data onto the network, and causing problems.

Can anyone direct me to a web site that reviews and/or compares the VFDs of different manufactures, with particular interest in the Ethernet communication feature?

Any opinions on this topic is appreciated.

Thanks for your input.
Paul

Are you planning on getting new drives and soft starters or using the existing ones in your plant (if they have ethernet capability)? I don't know of comparisons between VFDs on the net. If I were you, I would go to the major brands' web site and download the technical PDF files for their VFDs and compare.

The problem here is that there is not one kind of Industrial Ethernet.

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I would pick the VFD based on what how it performs its "core service" as a VFD - kW or hp, fusing, braking, inrush current handling, local support, reputation of vendor, regulatory approvals, warranty, price, etc.

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Because:

There is PROFInet, EtherNet/IP, Modbus over TCP/IP and so on.

If you're buying Rockwell Automation drives then you use the ODVA flavour of Industrial Ethernet. If you are using Siemens SIMATIC drives then you get another flavour etc. Many "independent" drives allow you to pick a brick and get what ever flavour of Industrial Ethernet you want.

Frankly, I can't imagine a fair comparison anywhere. Most likely the "study" you're reading was funded behind the scenes by the "open" Industrial Ethernet group that funded the exercise.

So, I think you are on your own!

I've used a variety of Industrial Ethernets and I've been quite happy with all of them. They are all significantly easier than their traditional bus (or hard wired) VFD (etc.) devices to support. Debugging a ControlNet or PROFIBUS drive, for example, is always more difficult than the Ethernet alternative.

I have not experienced that problem. I do suggest a separate network for the VFDs and I/O drops from any plant or HMI connections. And use switches rather than hubs.

Paul -

I don't know of any specific comparison site per se, but our company specializes in communications and VFD applications. We also designed and supply the Ethernet cards used by several VFD manufacturers. If you have any questions, feel free to contact our support line, and we can discuss our experiences with the VFD manufacturers that we work with.

http://www.iccdesigns.com

Best regards,
Darrin Hansen
ICC, Inc.

I won't repeat but I will agree with most of what has been said thus far. I will say it's not gobs of data. Most VFDs in simple applications usually require two words each direction. A control word and speed command to the drive, a status word and feedback from the drive.

In complex applications and/or with drives that are more configurable you can get 256 words each way, but that's up to the application. If you're running pumps and fans conveyors and such you will only need two words each way....

No, there are no sites that compare them. In fact, there is nothing in the entire automation industry that resembles Consumer Reports. You won't even see a real "review" like you'd get on any of dozen audiophile sites. You'll have to piece things together yourself.

Having said that, let me assure you that people have been using Ethernet for drive control in mission-critical industrial applications for years. Yes, Ethernet can have issues. So can every other network.

As someone else said, it is best to seperate your control network from your IT infrastructure. This helps make sure that your Ethernet control network is not swamped by data or broadcast storms or someone plugging in a device with a conflicting IP address. I personally prefer to do this by having no connection at all between the two, but it can also be accomplished by using managed switches, VLANs, routers, and other technologies.

Re-iterating yet another person's point, the Ethernet side is not really what you need to worry about. Pick the drive that fits your application, from a vendor you trust, that works well with the system you've got. If you've got a Rockwell system, make sure the drive will speak EtherNet/IP. If it's a Siemens system go with Profinet. etc.

-James Ingraham
Sage Automation, Inc.

There are many options, but we have had success
using AB Powerflex 70s over Ethernet IP. Make sure you have the drives on their own dedicated switch and ENBT card. Or even their own subnet and you will not have any comms problems.

I would also suggest putting a switch near the drive itself. Long Ethernet runs can be problematical.

In addition to what has been said so far I would also suggest that you take a look at how your total control system will utuilize the drive data. The Schneider Electric Altivar 61/71 drives supports the Modbus TCP/IP IO Scanning functionality which makes it simple to implement the control strategy in the PLCs that support this functionality. At the same time the HMI can retreive the additional infomation that may be required. The Altivar 61/71 Ethernet Card has a daisy chain capability (Two Ethernet Ports.

In the intrest of full disclosure .....

Robert Willis
Schneider Electric
Houston, Texas

Hi Robert

does The Altivar 61/71 support Ethernet/ip?