controlling conveyor
kb2hap
Posts: 218
I'm starting a project where I want to control an small conveyor It has 7- dc motors· (90vdc) and 7 sets of diffused photo eye sensors. I am fairly new to basic stamps and I was wondering If anyone had any info on completed projects similar to this.· I'm guessing that I will need a darlington array to drive the relays for the motors. I dont think the photoeyes can directly integrate to the stamp pins due to the current draw. I belive there running 12vdc at 200ma max. this conveyor will run as accumulation but have options to control it with a foot pedal and also to send a signal so that you can hook more than 1 conveyor together.· I working on what is a microcontroller. and also have stampworks to thrust my programming capabilities into high gear (i'm used to AB PLC's) any help would be great thanks
dan
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DTQ
dan
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DTQ
Comments
As far as the optic eyes.....you could use a separate power source for those and just tie the photodetecter to your input pin (use proper current limiting resistors).
Be sure to check the datasheets on your opto's.· Make sure that you're not gonna commit Stamp Hari Kari...might look at optoisolators to your pins.· Again, too many and your stamp supply will reach it's limit.
I've always wanted to try a conveyor like system but don't have one to work on....cool project!
You'll probably run in to issues with noise from your motors...did you say they were dc or ac?· anyhow....give 'er a go and see what you can do!
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Steve
http://members.rogers.com/steve.brady
http://www.geocities.com/paulsopenstage
"Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."
I use Stamps for industrial control all the time, (and also use AD PLC's for the big jobs).
The Stamp can do this job easily. I have made a PC Board that uses Solid State I/O modules. There are 16 positions so you can add modules as needed.
There are:
AC Input Modules: Apply 24-240VAC inputs
DC Input Modules:· Apply 24-120 VDC
AC Output Modules:· Will Drive 24-240 VAC at 3 Amps
DC Output Modules· Will Drive 15 to 120 VDC at 3 amps.
You can have any mix of Input or Output modules. The limit is 16 total.
I do not have much documentation on the board as I use them in my own projects.
The Photo Sensors can directly drive an input module and the output modules can drive the motor contactors.
The Stamp is electrically isolated from the Conveyor circuitry.
This is not a sales pitch, as the board is easy to make.
The programming will be the biggest 'Change' from PLC's.
This is 1 instruction executed at a time, not hte whole laddder at once.
You have to make sure you do not get hung up waiting for a switch closure, as you will ignore everything else in the meantime.
You also need to make an Emergency Stop Circuit that will kill all motion and motor power, no matter what the Stamp says or does.
It is OK to have the Stamp Allow operation. Use an output in the E-Stop String to make sure the Stamp is awake and in control. The E-Stop must function no mater what the failure mode of the Control circuitry.
As for noise, I designed the board to work·with Plasma Cutting Equipment. This fires an electric arc with a 10,000 volt AC Spark. As noisy as 7 DC Motors for sure.
I run the Board from a seperate AC supply and use a Corcom type LC Filter on the AC power. The board has its own 120-240 AC to 5 VDC power Supply.
All the I/O points and the Serial link are filtered.
Hope this helps you with your design.
If you have any questions please let me know.
Thanks,
Alan Bradford
Plasma Technologies
www.plasmatechnologies.com