#1 - you cannot use the same coil twice. Consider your drawing, I push FWD, FWD coil is energized in rung 000, it latches, and as a result it is energized in rung 003 as well and the conveyor is going forward. Now I push REV. This causes the coil in rung 003 to drop out, but the coil in rung 000 is still energized. logic fail, 0 ≠ 1. For this reason, most software won't even let you place the same coil twice, or it will throw fits when you go to compile. What software are you using to draw this ladder?

Your ladder should look more like this:

However, this prevents FWD operation when the REV coil is latched, and vise versa, defeating your requirement of "from any state" (you would have to press stop between direction changes). Are you sure this is a valid requirement? Normally this is not advised, especially on a conveyor. Can you imagine a conveyor full of wine bottles trucking along in one direction at 100 FPM and you instantaneously reverse direction to 100FPM in the opposite direction?

If it's definitely a requirement from the instructor, I'll modify the ladder to suit.

Zazzoo, consider this:

           A             B
000  |----| |------------()---|
           (98 rungs of BS)
           A             B
099  |----|/|------------()---|
100  |------------------(end)-|

This would result in the output B being switched on and off a zillion times per minute. Let's say it's a relay output driving an inductive load. Swift destruction ensured.

By forcing you to use each coil only once, the software will cause you to find yourself changing the code to look more like this:

           A     A       B
000  |----| |---|/|------()---|
           (99 rungs of BS)
100  |------------------(end)-|

... at which point you would realize, "hey, that's pretty stupid. It will never energize"

 

#1 - you cannot use the same coil twice. Consider your drawing, I push FWD, FWD coil is energized in rung 000, it latches, and as a result it is energized in rung 003 as well and the conveyor is going forward. Now I push REV. This causes the coil in rung 003 to drop out, but the coil in rung 000 is still energized. logic fail, 0 ≠ 1. For this reason, most software won't even let you place the same coil twice, or it will throw fits when you go to compile. What software are you using to draw this ladder?

Your ladder should look more like this:

However, this prevents FWD operation when the REV coil is latched, and vise versa, defeating your requirement of "from any state" (you would have to press stop between direction changes). Are you sure this is a valid requirement? Normally this is not advised, especially on a conveyor. Can you imagine a conveyor full of wine bottles trucking along in one direction at 100 FPM and you instantaneously reverse direction to 100FPM in the opposite direction?

If it's definitely a requirement from the instructor, I'll modify the ladder to suit.

 

hey strantor...how are you doing. i am a new member of this site and i wanted to know if you could help me with some problems i am facing with my assignments.i did not have any means of reaching you so i decided to reply to this post/thread, can you please reply me as soon a possible .thank you

 

@osablud
Welcome to AAC. You posted to a very old thread with homework help so I have moved your posts to your very own thread.
Reference:
https://forum.allaboutcircuits.com/threads/help-with-plc-conveyor-setup.72381/#post-1118054

 

thank you very much... do you know how i could tag or direct message another user?

 

What's up?

 

thank you very much... do you know how i could tag or direct message another user?

Quoting another member's message will send him an alert. Looks like @strantor got the alert from the quoting. You can tag a member using the at-sign with the member's username like I did yours, and strantor's here.
After some minimum number of posts (10?) you can send a member a PM (private message) by clicking 'Inbox' on the main screen and 'Start a new conversation'.
Howzatt?

 

thank you very much @johnln TX

 

good evening @strantor can you please help me with the assignment problems i have? i attached the questions to my the post.thank you

 

If this is H.W, What have you come up with so far?
Looks like AB based (RSLogix).
Max.

 

I opened the attachments. Did not see your questions, just an assignment.

 

@strantor i know that i have not attempted it and that is because i don't know much about it.i am taking it as an independent study course which has two sections, which are control systems and PLC... i was able to pass the control systems section very well and the plc not so much. i was given this by my professor in order for me for me to boost up my marks.so please can you help me with the assignment because this is the last course i am taking and i need to get a certain mark in order for me to graduate.can you please help me.?

 

The general theory around here for homework is that someone either gets you started or checks an existing effort, if someone graduates for you, what's going to happen when you meet the issue in the real world?
Not really doing you any favours! .
Max.

 

For Lab 3, what are your inputs and what are your outputs?

 

input: extend and retract button/start and stop button,sensor input

output: motor and sensor data.

is that correct?

 

@MaxHeadRoom thank for your input and i totally understand what you are saying but i am in a tight situation right now and that is why i am doing this...if i can please get help with this because it is due today..i promise to learn from you gus and also it myself and ask necessary question on this site in order for me to be more comfortable with plc.

 

and also i would not be needing this after i graduate because i will be going for my another degree .plc is really the only course i am having a hard time with.so please guys can i get some help?

 

input: extend and retract button/start and stop button,sensor input

output: motor and sensor data.

is that correct?

Inputs:

• extend button
• retract button
• start button
• stop button - No stop button is mentioned
• "extended" sensor
• "retracted" sensor

Outputs:

• Extend solenoid
• retract solenoid
• Motor run

So create all those I/O in RSLogix, drop them in some ladder where you think they should go, and post a screenshot here.

 

It would help to try and establish just what exposure you have and knowledge if any, however trivial of ladder diagrams.
Do you have any reference material at all? For example, your Lab PDF mentions RSlogix which is an Allen Bradley product, although most PLC's have a similar format, the mnemonics used are sometime unique to a certain make.
If a certain reference to a rung mnemonic then it would help if you have knowledge of it?
You should by rights have at least one manufacturers PLC manual.
Max.

 

FYI I'm leaving the forum for a few hours. I will be back this evening.