still shift register error

[ddevins 0]

I'm at it again. I posted this program once before for a differet question. I am using ML1500 and PV550. This program has shift registers on rungs 119-123 with bits for each used several places in the program. Again me or the company didn't write this program, it came with a machine at the customers' site. The program checks for part and with 3-in-a-row missing will stop the machine. The last operation is welding the plastic parts together and checking the weld. A bad weld used to stop the machine. After the weld is a reject or good part register. At the last position, the part is picked up and drop into a good bin or reject bin. I added logic to get three bad welds in a row before the machine will stop. But I must have made a mistake in the shift register or missed a bit in a rung. What is happening now is that when a bad weld is detected and a good one right behind it, both parts are rejected and dropped in the scrap bin. Hope this makes some kind of sense. Can anyone see where I goofed and am getting a good part after a bad weld being a rejected part?? This should open and be renamed as RSS file. Thanks for looking. devins7.zip

[TimWilborne 108]

I give up, I still can't open the file

[jstolaruk 9]

I couldn't either. Here is WinZip's error report of the file: End-of-central-directory signature not found. Either this file is not a Zip file, or it constitutes one disk of a multi-part Zip file.

[Mickey 71]

Its not a zip file just change .zip to .rss and open it.

[ward 0]

What initiates the reject cycle? Is rung 84 the first rung in the cycle?

[Chavak 2]

Ddevins, Do you increase the T4:100 value for some reasons, or is it orginally set for 250. The double coil for Weld Reset - O:0.0/4, also make me unconfortable. Do you have a copy of the program before you made the changes, if yes pls post. Then it will be much easier to check. I am guessing your Reject Weld Control B3;4/2, never gets reset for some reasons which makes the next part bad. Good Luck __________

[ddevins 0]

Everyone, I certainly appologize for being so difficult. I cannot attach a RSS file so I change the extension to ZIP with the intent for people to save the file, change the extension to RSS again and open. The original program is attached here as requested. I will look at suggestions made above and see if I can find my error also. Again, sorry for the frustrations and also many thanks for any comments. devins_ORIGINAL.zip

[TimWilborne 108]

You should be able to post the RSS file the same as you post the ZIP file devins_ORIGINAL.rss

[Chavak 2]

Ddevins, Just a trouble shooting tip Open RS Logix 500 Tools -> Compare ...........This opens up a dialogue box, Select the base project (Your Original one maybe) and select the Compare Project (you can either browse the project from hardisk or upload from PLC) and hit OK Select the attributes, normally I deselect the data files and type mismatches -> hit OK. This gives you a direct view on what you have changed. _____ I just did it on your programs, there are quite a changes. In rung 103, the welder reject input is directly driving the timer T4:100 set for 2.5 seconds. If the input from welder do not last that long, the timer will never get fired. But you can do a self holding to make it complete its course, if the cycle time permits. You are using the timer to cut off the Reject Control bit B3:4/2, which is of course is the Shift Register determinant. If the timer T4:100/dn or B3:0/1never get fired, the part will be considered bad. Good Luck _________

[ddevins 0]

Chavak, Yeah there are several changes from the original program. They have had me do several things to speed up the turntable machine. I apppreciate your assistance. If I understand you, just changing the timer T4:100 to a much shorter time will probably fix this---correct?? That will make the timer timeout each sequence table movement and reset as needed. I have more to do and will be working on it this weekend and probably Tuesday at work. It involves rungs 39-50 changing the sequence of the reflux movement. I have tried many things but to no avail. I have this in a previous post a couple or three weeks ago. I may post it when I'm done and see what comments I get. Just changing the order or the rungs doesn't quite work as I tried on the machine. Again, thanks for the help.

[ward 0]

"Just changing the order of the rungs" won't change the sequence of a machine because the outputs only update at the end of the processor cycle after the program logic has been executed. You'll have to modify the logic to change the sequence. http://www.plcs.net/chapters/howworks4.htm Edited 3 Sep 2006 by ward

[Chavak 2]

Hi, I do not fully understand the purpose of T4:100, Also look at the double coil of O;0.0/4. any way I should have done the logic something as shown.

[ddevins 0]

Thanks for the time and assistance. I didn't know that was 2 coils for the welder reset relay. I combined them into one rung. You think I can just get rid of the timer T4:100 and its done bits and be OK??? I'm also going to try the simulator on the sequence change I have to do later today. That should help since I haven't had any luck with it even though I was close once. Chavak and ward----thanks for this and I'll keep working to get better. I'll let you know in 2-3 days how this is working in the field.

[ddevins 0]

IT WORKED PERFECTLY!!!!!!!!!!!!!!!!!!!!!!!!!!!! THANK YOU THANK YOU!!!!!!!!!! Chavak and ward and the others. Both the sequence change and shift register changes worked first time.