PLC student looking for some tips and help

[GirlEngineer]

Hey I am looking for an active member that has some time to help explain a little bit more about the RS logix program. I failed last semester due to lack of understanding. I am able to turn in the programs I did last semester but a few of them need tweaking. I am currently working on the traffic 1 program and I cannot seem to figure out how to add a 1 sec delay for the red lights I am taking the class online due to the coronavirus taking over everyones lives. I can upload what I have already completed by I'm not sure how to do so..


if anyone can help please email me @ [email protected].

Thank you in advance,

Girl Engineer

 

[willxfmr]

Welcome to the Forum!

To post your logic, you must first zip the folder, then attach it to your post (forum rules).
Once we can see where you are at, then helping move things along should be no trouble.

For the problem you are having right now, the .TT bit in the TON instruction can be your best friend.

Bubba.

 

[parky]

Welcome to the forum, Post a reply on this post and at the bottom you will see a button that says attach files, press this, and it brings up a pop up window where you can select files, there are some buttons, choose file this brings up the file manager, select the file(s) and then press the upload button. It is best if you use a zip program to reduce the file size as there is a limit on the size of files if you are not a supporting member (300kb) if your program is too big even when zipped up, print sections to pdf's i.e. split the logic up and then post the pdf's.

 

[cardosocea]

Perhaps a single timer and checks on the Elapsed time to move between traffic light states?

 

[gclshortt]

This series takes you through using discrete inputs and outputs to control traffic lights and cylinders. As we progress we introduce additional methods to solve logic. We look at sequencers in a new way and learn how to write programs to allow users to teach the new sequence. Here is part 1.

https://accautomation.ca/building-a-plc-program-that-you-can-be-proud-of-part-1/

https://accautomation.ca/programming/plc-beginners-guide/

The above may help you out.
Regards,

 

[Operaghost]

As was said by others, post your code and you'll get lots of help. We are always eager to help students that put forth the effort. Others have come here and asked us to do their work for them and they don't get much help.

It is helpful (for me at least) to remember these key points with Rockwell timer status bits:

• .TT - Use the timer timing bit whenever you want to make something happen FOR a period of time. For example, a strobe should flash for thirty seconds after pressing the conveyor start button
  
• .DN - Use the done bit whenever you want to make something happen AFTER a period of time. For example, thirty seconds after pressing the conveyor start button, the conveyor should start moving

Notice that in this example, the DN bit does not have anything to do with how long the conveyor runs. It simply delays turning on the conveyor. The .TT bit on the other hand specifies the exact time that the strobe will flash. Sometimes it is easy to over think the usage of these bits.

And then as for the timers themselves.....

• Use the TON Timer On Delay when you are trying to turn something ON after a period of time. The TT portion really can use either timer.
• Use the TOF Timer Off Delay when you are trying to turn something OFF after a period of time.

So ask yourself, are the red lights turning ON for a period of time or after a period of time.

OG

 

[JRoark]

can you post a process description for the assignment?