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First Experience - Emerson - Control Techniques FM-3 Servo Drive

Article ID: 68
Last updated: 13 Oct, 2010

For those of you that aren't familiar with my writing style, this article is what I call my first experiences. This does not mean this product is brand new on the market, but rather the first time I've personally had an integration application using this product. I will also share my learning curve ratings at the end of my first experience articles.

One of our suppliers Allied Automation out of Indianapolis, Indiana, has been trying for quite some time to get us to use the Emerson servo drive products. Of course like anyone else, sometimes you get tunnel vision with certain types of products you may encounter. In my case, I was using Allen Bradley Ultra Drive servos and was pretty much blinded. I try to always caution others about this tunnel vision problem that Controls Engineers can get. If this happens to you, stop, take a deep breath and open your mind.

ne day we had an application come up that we felt an Ultra Drive product couldn't handle, so I was told at the time that we might have problems using an Ultra Drive in an indexing table application because the resolver doesn't roll over automatically, or we would have to reset the resolver with a sensor every revolution of the table. At first, we really didn't want to hassle with this reset and thought that surely someone else has come up with a servo that can be used in a one-way only indexing table application. Right? Without much thinking we called up our buddies in Indy and talked about that Emerson servo again. After a couple of phone calls we found out that the Emerson drives have an automatic resolver roll over for our indexing table application so we decided to give the servo a try.

With out much further a-do, we ordered one of these drives and it arrived pretty quickly. Of course like any other servo motor I've seen, it looks pretty standard as you can see from the pictures below. The servo motor cables are "armu" grade.

The motor is long, but I don't think dimensionally it's any longer than most servo motors. Our application uses an 8:1 inline gearbox to bring the ratio down on our index table application.

The dial table that was designed is rather small and contains 72 stop positions, or in a 360 degree table at 8:1 equals 40 degrees of motion every time the motor was told to index.

What makes me smile about this Emerson drive is of course the servo controller. We used the FM-3 model with our indexing table package. This controller is a drive and indexer all built into one unit. Which means you can do all your programming inside the controller and just send a "go" signal from the PLC to this controller and it will handle the motion move program. It's a low powered unit and accepts any range of voltage from 90-230 VAC single phase. I think anything that has such a wide range of input voltage must be pretty flexible. The controller has some I/O that you can program to anything you want inside the controller. It's virtually all drag and drop to assign I/O to any of the physical I/O outside the controller. 

The software that comes with the Emerson servo is called Power Tools Pro version 3.0. Let me tell you what, I was really tickled how easy this software is to used. It's a menu tree based software that I found very intuitive and easy to use. Everything makes sense what you need to access in the servo controller. From assigning I/O, to setting up your homing motion, to finally writing a simple program. Once you use this software I think you'll agree. The controller saves everything inside the controller flash. So if you don't have the original program, it's ok because you can upload the program and all the comments direct from the drive. I wouldn't never recommend relying on this method of uploading software from any device, because the device could fail any time, then your not going to be your bosses best friend anymore. However at any point, if you need to, you can upload everything from the controller and not lose any monetary value in your program or comments at development time.

I found it very easy to assign I/O points from internal status bits in the controller to real world physical I/O points on the controller. This was very handy to send signals from the servo controller to the PLC so the PLC knows the status of the controller at all times. You can even assign I/O or conditions within the controller to stop other internal signal. For example, there is a flag in the controller under RAMPS>STOP which if active will stop the current motion program and end your program. I needed my application to stop executing the program if the drive enable went low, so I dragged the status bit from DriveEnableStatus to the Ramp>Stop function. Now when the drive enable drops out, my program stopped executing. This servo indexer still executes code when the drive enable goes low by default. I can see where this is extremely handy in some applications. You'll probably want to use this feature when you hit an e-stop but you don't want to lose your program. Of course if your program comes to a point that it needs to issue a motion command while the drive is disabled, I think your going to be stuck. But if you have a desire to keep executing your program even after an e-stop occurs, you have the option to do so out of the box on this controller. In my case, I wanted the program to end no matter what on an e-stop so I used the internal mappings of two internal bits to accomplish what I needed. 

Setting up the index move was nothing more than double clicking on the first index0 profile tree menu and filling in the wizard form for what I wanted that index0 to do. Since I only have one motion profile for an index table, I only needed to setup one index profile. In my case, I need to move the motor 40 degrees for each of the 72 stations.

Last but not least is the programming itself. It's a structured text language similar to basic or visual basic. Very easy to use, you can even drag and drop conditions from any of the tree menus right into your conditional statements. When you do this, the software automatically comments the programming lines. This makes it pretty fast and easy for you guys who forget to comment your programs.

In summary, I thought this servo package was easy to use for a first timer. I'll definitely use it again in another application. I don't recall having any issues with the drive at all. I didn't have any tuning problems, nor did I have to adjust any tuning parameters to get the drive to run. Everything worked out of the box with no known problems. 

Technical support from Emerson was good since I only called once to the tech guy asking about stopping the program on an e-stop, which I used his suggestion above.

Learning curve rating: 

Curve 0 = Walk in the park.
Curve 10 = Get out the scholastic cap and crash in the classroom.



I gave this device a "1" learning curve rating. Very easy to integrated to a PLC.


You can download my electrical drawing for the Emerson FM-3 here:


Watch this servo in action, download the application video:






Article ID: 68
Last updated: 13 Oct, 2010
Revision: 1
Views: 11210
Comments: 5
This article was:   Helpful | Not helpful
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Randy Weinheimer | 06 Dec, 2004 12:00 AM
After reading your article I think you have some incorrect information. The U3000 has the ability to Rollover at any count/user value you setup in the drive. I'm not sure why this was not explained to you but the capability is there. Additionally Rockwell offers a more complex drive known as an Ultra5000 which programs in ANSI C and has pre-configured libraries of commands similar to what you speak of in the Emmerson drive.
Posted: 13 years ago   | Permalink
Chris Elston | 13 Dec, 2004 12:00 AM

Thanks for your comments. There are a couple of things you should know. First, I never mentioned which Ultra Drive I looked at, if the 3000 series could do this, maybe it's not compared apples to apples with the Emerson drive. Second, I understand as of today 12-13-2004, that Allen Bradley has an Ultra 1500-I made for an indexer application. At the time of the article, the application was complete 8 months prior. Alot of times I don't get around to writing articles until sometime time after the application is installed in the field. Also it might not be fair ten months later to say Allen Bradley has a product that can compete with this Emerson application. Maybe at that time the Ultra 1500-I was not availible. I don't know until I am told differently. From my stand point I always have to look at price. Are you saying the Ultra 3000 is priced the same as this Emerson drive? If not, I wouldn't have bought it just for the features only, price has to be allowed into the comparsion. Thanks for reading my article, your welcome to share and post any more thoughts.
Posted: 12 years 11 months ago   | Permalink
Randy Weinheimer | 14 Dec, 2004 12:00 AM
Chris, I apologize for assuming the Ultra 3000 was the comparator. Judging from what I had read in the original article I would have applied an Ultra 3000 to the application. The capabilities of the Ultra 3000 or Ultra 5000 would have been available in the time frame you spoke of, so I think it would be fair to compare the Ultra 3000 or Ultra 5000 to the Emerson drive in capability. I would not compare the Ultra 1500 to the Emerson; The U1500 is not a stand alone indexer the Ultra 3000 is. I also understand the issues with price but I am not privy to Emerson customer pricing and do not know what if any, the cost differences would be. I mainly did not want a reader to assume that the AB solution was not attainable when it appears to be viable.
Posted: 12 years 11 months ago   | Permalink
Chris Elston | 15 Dec, 2004 12:00 AM

No need to apologize. I thank you very much for sharing your comments. I'll be the first one to admit I am sometimes wrong. Sometimes people can tell me the wrong information or I can mis-understand what I have been told. I went back and looked at the quotes for this project. We did have an Ultra Drive 3000 quoted. The price was $8,102.30 for the complete package. Then we had an Emerson quoted. The price was $3,434.40 for the complete package. One of the other problems that I failed to mention in my article, because I wasn't dwelling on Allen Bradley, we had a problem getting a comparable gear box solution to work with the Ultra Drive 3000. Our AB people ran the numbers in AB spreadsheet software and came up with a hefty gearbox. It was made by Alpha and the cost of the gear box was $5,622.00. Emerson ran the same loads and came up with a smaller cheaper gearbox, I forgot the name, but it cost was $712.00. I don't really understand what the issue was with the gearboxes, but that was the major decider in the cost. I assume each company knows what their motor is capable of handling as far as inertial loads. In the end, the Emerson product performed well. I don't remember experiencing any problems with loads or speeds. Our cycle time was 0.25 seconds. Every 1/4 second the index table had to move. Cost wise, if the gear box had not been the issue, the Ultra Drive certainly may have won the battle.
Posted: 12 years 11 months ago   | Permalink
Jim Beausoleil | 22 Aug, 2007 12:00 AM
Very good article. I use emerson servo drives (EI205, EI202,) & motors. I have not used this drive servo combination yet, but will if an application comes along. I find emerson to be much cheaper and more flexable than AB. I use Emerson FM tools it's great software and very easy to use.
Posted: 10 years 3 months ago   | Permalink

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