Cheapest solution for Linear Positioning feedback to PLC ?
Cheapest solution for Linear Positioning feedback to PLC ?
(OP)
I need my PLC program to know where the object is located in order to branch out to next operation. This object that can move within 2 inches between point A and B only in straight line fashion so that ease the detection. What is the best way of "knowing" where the device is sitting between A and B in 0.1 inch resolution? Servo positioning is too expansive for my project. Can anyone tip me any better solutions ?
Thanks!
Thanks!





RE: Cheapest solution for Linear Positioning feedback to PLC ?
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If we learn from our mistakes I'm getting a great education!
RE: Cheapest solution for Linear Positioning feedback to PLC ?
RE: Cheapest solution for Linear Positioning feedback to PLC ?
Let me also welcome you to Eng-Tips.
Cheers.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Cheapest solution for Linear Positioning feedback to PLC ?
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RE: Cheapest solution for Linear Positioning feedback to PLC ?
They're ok in fairly clean environments and for non-continuously-modulating service. We evaluated them for governor servo position feedback, largely because we were ordered by a cost-obsessed manager, but had some major concerns in that application. We went for a magnetostrictive sensor housed within the hydraulic cylinder. The big downsides for our application were: pot track wear, even on a conductive film pot; bearing wear for the pot shaft; marginal accuracy for what we were trying to achieve; and inevitable fine abrasive dust ingress past the seals once the dust killed the seals. We did use them for a couple of jobs where we need to quickly get reasonably accurate valve position indication for fault diagnostics, and they were easy to install, easy to set up, and were a fraction of the installed cost of a magnetostrictive type. If you are aware of both the limitations and benefits they definitely have their applications.
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If we learn from our mistakes I'm getting a great education!
RE: Cheapest solution for Linear Positioning feedback to PLC ?
RE: Cheapest solution for Linear Positioning feedback to PLC ?
And thanks for the additional eye opening Scotty I will keep that in mind.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Cheapest solution for Linear Positioning feedback to PLC ?
We switched to Ametek/Gemco magnorestrictive on some machines and Banner LT3 lasers on others. One of our service guys actually had to duct tape two toothbrushes on the string to clean it off as it wound back up.
I think there are much cheaper short range laser sensors out there. Keyance comes to mind.
RE: Cheapest solution for Linear Positioning feedback to PLC ?
Well yeah, there are engineers who thoughtlessly misapply stuff everywhere. I wouldn't hold that against the product. I do take your point though - not a good solution in some contaminating situations. Roger that!
Keith Cress
kcress - http://www.flaminsystems.com
RE: Cheapest solution for Linear Positioning feedback to PLC ?
My vote is for the magnorestrictive sensor. The lasers have a warm up time and are a bit noisy.
RE: Cheapest solution for Linear Positioning feedback to PLC ?
Keith Cress
kcress - http://www.flaminsystems.com
RE: Cheapest solution for Linear Positioning feedback to PLC ?
We started using guided wave radar to indicate mechanical positions and fluid levels. Check out IFM efector.
Hope it helps. I'm usually the guy asking the questions.
RE: Cheapest solution for Linear Positioning feedback to PLC ?
Keith Cress
kcress - http://www.flaminsystems.com