Dartrunner
Member
The perfunctory "I am new to this."
Just getting started in PLC programming and am trying to write one for a Siemens S7-200 CPU 224.
The application is checking bottles for a UV coated label as they travel by on a conveyer and then blowing them off about 3ft down the line if there is no label. The bottles are spaced about 6in apart and traveling between 90 and 120 bottles a minute.
I am able to detect the presence of the bottle’s neck and trigger the UV cameras to find the bad ones with out a problem. The problem comes in tracking the bottle down the line and ejecting the correct one. I have a presence sensor at the blow off point and an eye verifying that the bottle was ejected. I have tried to do it with timers and such but keep running into problems because of speed variation and the bottles vibrating on the conveyer. I looked at using a shift register, but guess I am having a brain block on understanding how to apply it. Also tried using an up/down counter, which would work for a while, but seemed to start getting the wrong bottle after a while. Sometimes getting as much as 4 bottles off. The line is sometimes powered down and brought back up with the bottles wherever they were when the conveyer was stopped. Other equipment on the line can also stop the conveyer (I think this was the biggest problem with the counter idea, bottles stopping under the presence eye.) and this controller will also stop the conveyer if an ejected bottle is not seen in the chute. (I think I have that one programmed)
Any suggestion would be very welcome!
Thanks,
Bob Smith
Just getting started in PLC programming and am trying to write one for a Siemens S7-200 CPU 224.
The application is checking bottles for a UV coated label as they travel by on a conveyer and then blowing them off about 3ft down the line if there is no label. The bottles are spaced about 6in apart and traveling between 90 and 120 bottles a minute.
I am able to detect the presence of the bottle’s neck and trigger the UV cameras to find the bad ones with out a problem. The problem comes in tracking the bottle down the line and ejecting the correct one. I have a presence sensor at the blow off point and an eye verifying that the bottle was ejected. I have tried to do it with timers and such but keep running into problems because of speed variation and the bottles vibrating on the conveyer. I looked at using a shift register, but guess I am having a brain block on understanding how to apply it. Also tried using an up/down counter, which would work for a while, but seemed to start getting the wrong bottle after a while. Sometimes getting as much as 4 bottles off. The line is sometimes powered down and brought back up with the bottles wherever they were when the conveyer was stopped. Other equipment on the line can also stop the conveyer (I think this was the biggest problem with the counter idea, bottles stopping under the presence eye.) and this controller will also stop the conveyer if an ejected bottle is not seen in the chute. (I think I have that one programmed)
Any suggestion would be very welcome!
Thanks,
Bob Smith