Page 1 of 5

Let's automate everything hehe(interfacing PLCs+)

PostPosted: Fri Aug 31, 2012 11:49 am
by nix
Is it possible to interface with SEW eurodrive?
hope cheer

I have decided to turn this into a general thread about motion and control, industrial applications
and invention, and how FS fits into this.

Re: Interface PLCs?

PostPosted: Thu Mar 13, 2014 4:36 am
by nix
I've been quite successful doing audio stuff with Flowstone,
now I'm thinking I'm going to find it more satisfying to get into machine control/hardware.
It would be fun to play with steppers and Phidgets-
maybe build a drawing machine-
but I think it would be best if I looked to some more power than 5-10V .5A,
so I am dredging this old topic up. I have like 5 SEW PLCs,
I couldn't find them on their site->
Anyway, they are an AC PLC for around 10-15 amp motors.
To begin with,
I was wondering if I could interface a tachometer I have built, somehow.
It would be cool to turn a winding machine off after say 1000metres have been run.
I was wondering what I can use my FS knowledge in in industrial machine design/control.
Everyone is very welcome to drop into this thread with ideas, solutions and chat.
I will rename it something more general, and OT is fine-
I'm sure it would be in and around the point.
So I'm looking for starting points of useful applications,
specific implementations-
I have decided to embrace the motion and control side of FS finally.
So the concept of what this thread is is a bit hazy.
I will come back with more specific questions when I think of them.
I think I will.
Will try and get the info on the input pins of these PLCs,
I have built a winding machine that was/is around 3.6kw-
I want to be able to use(say) a Flowboard/Phidgets8 to interface with this kind
of power when necessary.
Also will come back with another post that details all my engineering applications-
hopefully starting some cognitive gears turning 8D

Re: Let's automate everything hehe(interfacing PLCs+)

PostPosted: Thu Mar 13, 2014 11:36 am
by nix ... _id=1002_0

Do you guys think this would be appropriate for driving a tiny( Epson printer) unipolar stepper?
The pins in FS look right. I could use 1.5 volts, would it draw too much amperage?
Any hints for connecting multiples of these(setting ids)?
I would need 3 to make a black and white printer.
I can manage the drive logic, it would be fun to actuate FS

Re: Let's automate everything hehe(interfacing PLCs+)

PostPosted: Thu Mar 13, 2014 8:10 pm
by MyCo
nix wrote:

Do you guys think this would be appropriate for driving a tiny( Epson printer) unipolar stepper?

I don't think so. The current from this is to low to drive such a big stepper. Also you don't need an analog output for this, a digital output with N-Channel Mosfet should do it. No matter what you use to control the stepper, you'll probably need an external power supply, because the USB-Port doesn't supply enough current.

Re: Let's automate everything hehe(interfacing PLCs+)

PostPosted: Thu Mar 13, 2014 10:40 pm
by nix
Thanks Maik!
I will read about the mosfet more and try to understand.
I think you are right about drawing too much current for USB.
I am going to need an externally powered board.
Analog is the way I want to roll though,
just using 4 analog outputs,
one connected to each stepper wire.
Is there any reason not to do that?
Does anyone know of such a board which will integrate with FS?

edit- Could I possibly use the analog output board with a current amplifier?
edit2- to do this, Is the major component I need a transistor? ...and that is a mosfet?
What is the advantage of using a digital signal? It will be purely 5 volts,
is that correct?

Re: Let's automate everything hehe(interfacing PLCs+)

PostPosted: Fri Mar 14, 2014 3:29 am
by MyCo
Mosfets are pretty easy parts when you only want to use them as switches. They are special kind of transistors, there are basically 2 types, N-Channel and P-Channel. You need N-Channel-Mosfets. They operate like a voltage controlled resistor. When the voltage is high enough, the resistor is very low (mostly only a few mOhm).

I've attached a schematic how you can drive the stepper with nearly any USB interface. But you have to make sure, that the external voltage source that drives the motor shares the same ground with your interface board. The interface board should have an isolated USB connection though.

You have to select the mosfets by some parameters, like:
N-Channel Type
ID > stepper current
VGS(max) > 5V
VDS >= Supply voltage
RDS(On) at 4.5V as low as possible
Qg as low as possible

You should use digital outputs to drive this, because it's much easier and cheaper... Also analog outputs are mostly very slow, because digital to analog conversion takes time and this reduces you drive speed.

Re: Let's automate everything hehe(interfacing PLCs+)

PostPosted: Fri Mar 14, 2014 10:18 am
by nix
Mighty Thanks!!
I will give this schematic to an electrical engineering shop to build,
when I pursue stepper control.
Is the USB port on Phidgets or Flowboard isolated,
do you know?
What do the resistors do?(sorry, I really should know)
So I will use digital, and not control the voltage,
as would be possible with the analog.
What measures do I need to take to stop my power supply overheating,
if I use the signal to brake as well as move? Is that going to be a problem?

So it seems 128k streams(or 44.1) is a really great signal.
The Phidgets are running at 1k.
Do you think peeps you could plug a USB soundcard into a Flowboard?
My tachometer needs the high data rate.
It will not work at 1000hz at all well.

Re: Let's automate everything hehe(interfacing PLCs+)

PostPosted: Sat Mar 15, 2014 3:57 am
by briant1972

I work on industrial controls for a living and I've done quite a bit of PLC and DCS programming. As a side project for a friend of a friend, I used Flowstone and a Labjack U3-HV with the relay board in an effort to automate a small readi-mix concrete factory. The basic operation is to put the right amount of water/cement/sand/stone/chemicals into a cement truck. The Labjack would turn on the solid state relays which would turn on solenoids that actuate big air cylinders and would also turn on starters for conveyor belts/chemical pumps. What I did with Flowstone and the Labjack was a fraction of the cost of using a typical Rockwell PLC/HMI. Also, it's easy to get fancy with Windows related things that you can't easily do with a PLC. I found a nice touch screen panel PC (fanless with solid state hard drive) and I was 99% done with the software and the guy backed out at the last minute. It was interesting at least. I actually programmed it first using Labview but since it's so costly it's not like you can install the development environment on a client's system so you can debug/troubleshoot it easily to so I opted for Flowstone and I definitely prefer working with Flowstone.

I've seen quite a few SEW Eurodrive motor/gearbox assemblies in paper mills. They normally seem to use a different brand of drives for them though. I think SEW Eurodrive is trying to sell these hybrid PLC/drive units to control their motors but haven't run into any of them yet. I'm curious about what model SEW unit you have. I might be able to find a use for one of them.

Re: Let's automate everything hehe(interfacing PLCs+)

PostPosted: Sat Mar 15, 2014 10:33 pm
by nix
Thanks for the input mate,
nice to hear this kind of stuff is do-able with FS,
and I read with interest. HMI and DCS are new abbreviations for me.

This is the little laptop I'm thinking of using if there is call for it->
They are around $AUD300.

I'm in two minds about cannibalizing all these PLCs and motors.
They are part of a disused wrapper for 8 square metre dam covers,
I need to be sure it will never be the method used if the product is pursued.
I can go and take photos of all the parts that seem re-purposable.
In this case the motors are not SEW. The PLCs are the unit of
choice for Integrated Machinery last decade. One is almost twice the size of the other 4.

Will look into relays and solenoids, with an eye to what they can do for me.
Thanks and all success

Re: Let's automate everything hehe(interfacing PLCs+)

PostPosted: Sun Mar 16, 2014 2:19 am
by nix
I have an electronics question. If the generator and the motor in the schematic are
small DC motors, does the motor climb in speed?->
generation question_0.png
generation question_0.png (417.52 KiB) Viewed 49804 times