Back again with project 2

[Terry Woods]

I haven't had a chance to read it... but I really can't wait to get into it!

Bryan... Good for you! I very glad that I didn't scare you away!

However, despite my Traffic-Controller comment, I'll reserve my judgement as to whether or not you are a real player.

Bryan... any idea what MGD is?

HEY! I didn't post that as a general question for all of you!!!

 

[bryan372002]

No Terry I do not know what MGD is. I dont think.....lol

Guys Despite what anyone thinks or says about Myself and my abiltities and or knowledge, I am Real, I came Here to Learn and get advice from pros. and regardless of any discouragement or bashing I will if nothing else learn more than I know now and Be more valuable employee to the company I work for. I very well may never be able to do any real programming, wouldnt even expect to for years to come, and i understand very well the dangers associated with poor programming, and lack of Knowledge anyway.

So what is MGD?

 

[TimWilborne]

I know what it means to me
Burp:beerchug:

 

[ChuckM]

I very well may never be able to do any real programming, wouldnt even expect to for years to come, and i understand very well the dangers associated with poor programming, and lack of Knowledge anyway.

You may be surprised to see what opportunities increasing your knowledge gets you. Not all PLC programming involves something that can explode, crush someone's skull or rip their body parts off in a horrible fashion. If you work in the right department, and you manager is a leader, you will have opportunities. And those programs that can make something explode, crush a skull, or rip off body parts should always be double checked by someone else anyway.

 

[bob1371]

I haven't had a chance to read it... but I really can't wait to get into it!

Bryan... Good for you! I very glad that I didn't scare you away!

However, despite my Traffic-Controller comment, I'll reserve my judgement as to whether or not you are a real player.

Bryan... any idea what MGD is?

HEY! I didn't post that as a general question for all of you!!!

Lets see, typing MGD into google and hitting the I'm Feeling Lucky button I get this.
http://www.informatics.jax.org/
Are you using mice to test with?????????

Of course the second hit on google would be my favorite.

 

[Clay B.]

I know what it means to me
Burp:beerchug:

Needs some asprin for that?

 

[bryan372002]

Here is ladder I came up with based mostly on what Lancie suggested. it seems to work, but i am still playing with Steves suggestion.

 

[TimWilborne]

On problem I see is that once the machine relay is on you need to do something to keep the anti tiedown timers from dropping the machine relay back out

 

[bob1371]

Okay, you asked for no solutions, just the framework.

Use 3 rungs, one for each timer, and the last for the relay. Call the relay "MACHINE INDEX". Do not seal in the relay. It triggers the machine and thats all.

On the first rung arrange the inputs so that Timer 1 can be started by either PALM switch. Set the Timer for 3 seconds per your instructions. That is too long for real-world machines, but necessary to allow you time to flip the switches on the LogixPro simulator, because you can only flip one at a time.

On the second rung arrange the inputs so that Timer 2 can be started by either FOOT switch.

On the third rung, add 2 timer contacts and 4 switch inputs so that only if all are closed at the same time, the MACHINE INDEX relay is energized.

I could have typed the rungs quicker! I did type the rungs into LogixPro to test it and the above will prevent the switches from being tied down, and also prevent the machine from indexing unless all switches are pressed, only if all logic is entered correctly.

As many have said, this safety circuit should not actually be built using a PLC. This is serious stuff. People get killed because of improper safety designs. My wife's cousin's brother-in-law stuck his head under a stamping press and it indexed and crushed his skull into a bloody pulp.

Bryan
Looking at lancie's post reread and see what else you might come up with. Your getting there though.
Bob

 

[bryan372002]

Thanks TW You are correct, what i thought about was using the relay to latch in a cycle start, then when the cylce completes the relay would unlatch.


And thanks Bob, i see You highlighted where Lancie says "either palm switch or foot switch" the only reason i wrote it the way i did was the instructor stated that the 2 foot switches made at same time or 2 palm switches at same time would start first timer. Thats my fault i guess for not passing on that verbal statement the instructor gave me.

Thanks again for your Input, really appreciated.

 

[DDV]

Terry did you know that MGD is owned by a South African company…..?

 

[Ken Moore]

There's nothing to prevent one hand switch and one foot switch from being tied down with a broom handle or other heavy object.

Here is ladder I came up with based mostly on what Lancie suggested. it seems to work, but i am still playing with Steves suggestion.

 

[Steve Bailey]

Bryan,

The logic you posted creates a 3 second delay following closure of the second of two sets of switches before the machine can start. Your "Machine Relay" will de-energize if any of the switches are released.

It is not an anti-tiedown.

 

[Rick Densing]

Bryan,

The logic you posted creates a 3 second delay following closure of the second of two sets of switches before the machine can start.

Actually it will create a pulse that will be on as long as the two timers overlap.

You are close to the anti-tie down. You just need to change two ANDs to ORs.

Then you have to decide how long you want your start signal to last.

 

[Steve Bailey]

Rick,

You're right. I misread the TT bits as the DN bits. Thanks for setting that straight.