Superior Electric Slo Syn Stepper Motor

Hi Guys , Thanks for the quick qesponse to my last question

I need all the information I can get for a motor I have and am using for a machine . I plan to use either an Alan Bradley P.L.C. or a comparable Omron P.L.C. >Which would you recomend ?
I have a Superior electric stepper motor Mh112-FJ 4201
The amplifier is a 3180 PTO . Could you lead me in the right direction to obtain the correct software and relevant information needed to control this motor?

Brian Crouch

Your motor's ratings can be easily found. Download this file : http://www.slosyn.com/manuals/3180 install.pdf about your drive's wirings and characteristics. You'll find in it the torque curve of your motor when used with the 3180 drive. Wirings are very simple : four leads only between your motor (two windings) and drive.

Since "big" motors (over NEMA 34 frame) are rated with high "Rotor Inertia" and "Detent Torque" values, their dynamic characteristics are relatively bad. Notice too how your available torque quickly decreases (less than half your rated holding torque at 2000 hz).

All depends on your project : we can explain how your motor, drive and PLC should be wired, but perhaps won't you get the results you're expecting for.

So, give please further explanations about your machine !

What I can say at the moment :
- with such a motor, you won't get great accelerations nor high speeds, but high torque at low speed.
- you could slightly improve efficiency with another drive.
- any PLC providing a pulse train output can run properly with this motor. Select preferably a PLC with trapezoidal control, allowing to adjust accel. rate, initial and maximum speeds separately. It doesn't matter that you purchase the last "state-of-the art" PLC with most high speed outputs : your motor won't follow it ! Directional output needed ? Origin return function + Home input needed ? Positioning ? Incremental or absolute movements ?....

Let's determine FIRST what are your application's requirements, let's check how your motor/drive can achieve them, and AFTERWARDS only, let's examine what kind of PLC has to be praised.

Regards

"- any PLC providing a pulse train output can run properly with this motor. Select preferably a PLC with trapezoidal control, allowing to adjust accel. rate, initial and maximum speeds separately...."

Any PLC can be made to Output a Pulse Train. Some are better at it than others. The Output type certainly imposes limits on what you can attain. For example, you would NOT want to oscillate a Relay-Output much faster than 1 cycle per second. You would get far better results from a solid-state output.

All PLC's that provide a dedicated Pulse Train Output certainly have higher level math capabilities (at least, I don't recall ever seeing a PLC with built-in, dedicated, Pulse Train capabilities but without high level math.)

The point of this comment is only to indicate that you can, if you are so inclined, "Roll-yer-Own" Pulse Train Controller in Ladder.

Speed!

Don't forget to figure the speed of your PTO - my trusty Micrologix can output only 20Khz, which is much too slow for most applications, and I've never been able to locate a pulse multiplier for this sort of application. I've made it work in the past, but never to my complete satisfaction.

Just a word of caution from the guy with egg on his face

TM

You're right Terry, nothing is self-evident and this point had to be mentioned : relay outputs are not useful with stepper drives (due to low freq. and undesirable bounces)!

There is a fact : each major PLC manufacturer has integrated in basic CPUs its own "PTO" function, in the recent past years only. One or two pulse output are often provided, even if, as you wrote Terry, some are better at it than others (many great differences exist).

But what was available BEFORE ? Usually, you had to buy and program some expensive "axis boards" in order to drive one or two steppers at 1khz.

As for me, I think that a few number of japanese manufacturers have "invented" this new market 10 or 12 years ago, with their micro-sized plastic boxes at low prices, when all brands were commonly selling big modular PLCs. I.e I've been amazed the first time I saw a KEYENCE's KV10 driving a labeling machine (OK, all was not perfect, but... running)

- WHAT A PLC ? - HERE ! - THAT SMALL GREY BOX ?

One of my actual customers has integrated "grey boxes" for around six or seven years, and really, no competitor could offer such capabilities at such price (in France at least...)! Decently, I could say that almost nobody knew or was interested by those kinds of markets. For vendors and customers, so small products were (are) not credible ! I've kept some KVs and sometimes I play with them for motor tests. I'm used to say that those guys were at least 10 years early for size, software, and hardware technology (MOSFET outputs on compact KVs, small modular KV300, +10 years old...).

I could mention other brands, but it could be mis-interpreted. I don't work with/for KEYENCE, so don't read this post as an advertisement ! Furthermore as you know, they currently prefer sensors, so they lost their advance in PLCs.

However, be sure that those dinosaurs have very, very low level math capabilities ! No calculation was required to perform their stepper ramps. It was only... I would say "clever".

Regards

"Little Grey Boxes"

BEGIN TANGENT:

Q:
What's the difference between a SBC (Single Board Computor) or an Embedded Controller, and a PLC?

A:
Packaging! (This includes both, the Little Grey, Black, Blue, or whatever colored Box AND the Interface).

Take an "Embedded Controller" (or, an SBC), remove it from the machine it is designed to control, and then put it into a nice, small, plastic box (color of your choice).

Then, add a user interface. Have the interface accept input in the form of LADDER Code.

What have you got now? In terms of the functionality and your access to that functionality, you have a PLC. This is NOT to be confused with a Field Programmable Array - State Machine.

I've been saying for years (go ahead, look through the archives) that there is essentially no difference between a PLC and a PC (especially, DOS-Based). The same can be said, in even stronger terms, when speaking about SBC's and Embedded Controllers.

The primary difference is the last layer in the interface - the layer closest to the user.

If the last layer looks for Ladder-type input, then most people see it as a PLC. And, of course, that layer can be designed to be nice and intuitive, or it can be rather archaic - depends on the design philosophy of the designers. (All too often you have to wonder... "What the Hell are they thinking???")

If the last layer looks for "C-type" input, then most people think it is more like a PC than a PLC. Certainly, some PLC's have a "C-Module", but, for some, it is still too much like a PC.

If the last layer looks for Assembly Language (very close to, if not exactly, STL), most people just freak out and say... "Forget that! I can't do it! That's too complicated! It's like... Computer Talk!!!"

It doesn't matter what the last layer is... user input is ultimately applied to the Assembly Language layer where the final Machine Code is developed.

So, my point is, programmers are closer to Assembly Language than they might think! That is, the difference between "PLC Programming" and REAL Computer Programming (Machine Code) ain't nearly as big as some would think!

Just somethin' that I felt that had to be said...

"END TANGENT"