Shop Floor Talk  

Go Back   Shop Floor Talk > Welding and Metalworking Forums > Mechanical & Electrical

SFT Search:   
Reply
 
Thread Tools Display Modes
  #1  
Old 05-31-2007, 11:40 PM
Bolt Bolt is offline
Elite Member
 
Join Date: Oct 2004
Location: Texas
Posts: 1,267
Default Linear Position Potentiometer Wiring

I have a gate that moves in a straight line along 200 foot of track.

I need to have some means of electronicaly knowing where the gate is, and running different controls off of it. I don't need anything accurate, just 10 foot increments or so.

For example:

If the gate is at the back (<70 feet), Relays 1-6 need to be energized.

If the gate is between 70 and 60 feet, 1-5 need to be hot.

If it's between 60 and 50 feet, 1-4 need to be on.

50 to 40 feet equals 1-3.

40 to 30 feet away, relays 1-2 are on.

30 feet or closer, just relay 1 is on. (I guess this wouldn't require a control then, as it would always be hot).

These are just some generalized descriptions, but I hope someone out there understands what I mean and what I'm trying to do.

I've found this site, and many others.

http://www.unimeasure.com/

But the part I am unsure about is getting the potentiometer's signal and processing it to run the relays. What do I need for such a task?

If it would help, I could probably get some drawings for you folks tommorow.

Or am I barking up the wrong tree here, is the cable pot the way to go, or maybe laser, or something else?
Reply With Quote
  #2  
Old 05-31-2007, 11:44 PM
BBchevy396's Avatar
BBchevy396 BBchevy396 is offline
Senior Member
 
Join Date: Jan 2006
Location: Washington
Posts: 522
Default

How about photo-electric eyes?..........
__________________
Or what? You'll release the dogs? Or the bees? Or the dogs with bees in their mouth and when they bark they shoot bees at you?
Reply With Quote
  #3  
Old 05-31-2007, 11:55 PM
Bolt Bolt is offline
Elite Member
 
Join Date: Oct 2004
Location: Texas
Posts: 1,267
Default

Well this application needs to be up and out of the way, where cows can't reach it, and relatively weather resistant. The problem I run into with eyes is they only know if the gate is right there, and not if it's beyond them and still needing to be "read".
Reply With Quote
  #4  
Old 06-01-2007, 12:15 AM
BBchevy396's Avatar
BBchevy396 BBchevy396 is offline
Senior Member
 
Join Date: Jan 2006
Location: Washington
Posts: 522
Default

Well, Ya didn't mention !.............
that changes everything!

( just funning with ya, I really can't help....sorry)
__________________
Or what? You'll release the dogs? Or the bees? Or the dogs with bees in their mouth and when they bark they shoot bees at you?
Reply With Quote
  #5  
Old 06-01-2007, 01:04 AM
GWIZ's Avatar
GWIZ GWIZ is offline
SFT Historian
 
Join Date: Feb 2006
Location: USA
Posts: 6,421
Default

I'm thinking.

How many relays do you need, 200' @ 10' = 20 relays.
Do you want the relays to turn OFF (in order) one by one if you close the gate every 10' ?

I assume 1-6 is relays 1 thru 6 and not #1 and #6 relay.
Reply With Quote
  #6  
Old 06-01-2007, 08:34 AM
MXtras MXtras is offline
Senior Member
 
Join Date: Jan 2007
Location: Virginia
Posts: 342
Default

To use something like this, you need to have something that knows how to process the signal - like a PLC (programmable Logic Controller) that can take the input from such a device and apply it to a simple program, or logic, that would produce a triggered output. Depending on exactly what you are needing to do, there is likely a more simple way. What about using limit switches and triggers? I do not know the mechanical arrangement here, but I think I understand the environment.

A cable pot is a decent idea, I think, and as I was reading your first post and saw the length, a cable transducer was the first thing to pop into my head. You might even be able to use a regular rotary encoder and get away from the cable if you elect to stay with the electronic control system.

What is the driving mechanism? Is it a chain or gear rack or ??

You might be able to put flags on the driving mechanism and then use latching circuits on relays and get away from any type of electronics other than a set of relays and a single limit switch. I can easily see this working, but then again I don't know the mechanical arrangement.

*******edit***** - after just a little thought on this arrangement - using a electromechanical arrangement with a single trigger could make it very tricky to recover from a power interruption if the gate was in motion during the failure.

What are the relays controlling and how is this gate driven?

Scott

Last edited by MXtras; 06-01-2007 at 10:09 AM. Reason: note on power interruption recovery
Reply With Quote
  #7  
Old 06-04-2007, 05:13 PM
Bolt Bolt is offline
Elite Member
 
Join Date: Oct 2004
Location: Texas
Posts: 1,267
Default

Here is what I have so far, not quite there yet, but getting closer.

In rung 10, whenever I change the second part of the equation to V100, it jumps back to TA100. Why does it do that?

I'm not quite done, and ran out of time for now, will get back to it later tonight.
Attached Files
File Type: zip Cooling2.zip (4.4 KB, 47 views)
Reply With Quote
  #8  
Old 06-04-2007, 07:06 PM
Bolt Bolt is offline
Elite Member
 
Join Date: Oct 2004
Location: Texas
Posts: 1,267
Default

What is the difference between a 3 way and a 1 way limit switch?

Is there a "double action" limit switch that makes one connection when going forwards, and makes a different contact when going backwards?

Otherwise I just need to go with Mark's code based on a single acting limit switch, but that would put me over the 100 bytes.
Reply With Quote
  #9  
Old 06-04-2007, 08:30 PM
markttu's Avatar
markttu markttu is offline
Chief Twidget & Keeper of the 'trons!
 
Join Date: Mar 2007
Location: Lubbock, Texas
Posts: 1,049
Send a message via ICQ to markttu
Default

OK, finally got a chance to look at the code and think about it. I think you're on the right track with this.

V100 = TA100, hence why you see TA100 any time you try to use V100. Click PLC, then Memory Map in DS to see how the memory is allocated. You may also want to check out the user manuals for the DL06 at http://support.automationdirect.com

3-way vs 1-way limit switch has got me stumped... Never heard of a 3-way limit switch. I've also never heard of a double action limit switch, but that doesn't mean there isn't one

There may be a more program efficient way to handle the gate tracking, I'll have to think on that a bit...
Reply With Quote
  #10  
Old 06-04-2007, 08:51 PM
Bolt Bolt is offline
Elite Member
 
Join Date: Oct 2004
Location: Texas
Posts: 1,267
Default

1 Way:
http://web4.automationdirect.com/adc...tor/ABM1E42Z11

3 Way:
http://web4.automationdirect.com/adc...tor/ABM5E42Z11

These are just the first 2 I found in a quick search, but there are a bunch like that.

I haven't figured it all out yet, but I'm getting there.
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Web Search:

All times are GMT -5. The time now is 12:23 PM.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2018, vBulletin Solutions, Inc.