Conveyor Belt

[Hodak04]

Okay, I have adjusted the program and I now see why I need the timer to be locked in. Also, I could use a Timer timing bit as well with the T4:1 instructions on rung 2 right? I didnt see why I wouldnt be able to, but want to make sure I am right before I change it.

 

[Lancie1]

Also, I could use a Timer timing bit as well with the T4:1 instructions on rung 2 right?

Yes.

I didn't see why I wouldnt be able to, but want to make sure I am right before I change it.

If you really want to make sure it is right before you change it, follow these simple steps:

1. Go to this link
http://www.thelearningpit.com/

2. Download the free-for-15 days LogixPro simulation software. It stops working after 15 days if you don't pay to get a code number.

3. Run LogixPro on your computer. If you are using Windows 7 or later, you will also need a way to run a virtual Windows XP version. I use VMware Player.

4. Select the "I/O Simulation". This allows simulation of a wide variety of programs, including yours.

5. Load your program into LogixPro, and add rung comments to each rung describing WHAT the rung Output is supposed to DO. You should have added rung comments as the first step - if you can't describe the action, it probably will not work as you expect.

6. Download your program to the simulated PLC.

7. Switch to Online mode, then switch from Program to Run mode.

8. Simulate the photoeye inputs using the built-in input switches.

9. Test your logic to find the errors.

 

[Lancie1]

Probably none of this is clear to your because you are not using rung comments, or putting labels on your instructions that let you know what each is doing. It really does make a big difference in understanding.

Testing your last program using LogixPro, here is what happened (see picture). When the LP Labeler Photoeye goes ON, Conveyor 2 stops as it should. But then it never restarts. It cannot restart because unlabled timer T4:1 (which is supposed to be the "Conveyor 2 Restart" timer) has some errors in its logic. T4:1 should restart Conveyor 2 on rung 1, branch 2, but instead it keeps the conveyor off (see picture). Instead of a XIO T4:1/DN on rung 1, you should have used a XIC T4:1/DN, and deleted the T4:1/EN.

Please Stop futzing around with these details, and put in the correct logic. I will fix it once more (the last time) and post a picture of the working version.

 

[Lancie1]

Here is a working version based on your last version, with corrections and additions to make it run.

 

[Lancie1]

Note that the Spacing Timer T4:2 needs to be a RTO Retentive type timer, so that when Conveyor 1 stops before the 3-second gap is created on Conveyor 1, the accumulated spacing time is saved until Conveyor 1 runs again.

 

[Lancie1]

The next big question is "how do you know that the robot and Conveyor 1 travels slowly enough so that your 3-second spacing time will not run a case from end to end"?

You don't know, unless you try to measure the robot cycle time inside your program.