Bit Shift Registers

Hello guys I am a first time user on this website. I am pretty new to control logix. I work in a fully automated sawmill and am working with shift registers to keep track of lumber and logs. I am working currently on hold down rolls in a debarker using a shift register to track the log through the 4 sets of hold down rolls. I am tracking it with one photo cell. The guy that set it up told me while tracking the log the press roll down position will always be greater than the up position in the shift register. So adjusting the timing on the open and close has me questioning his logic on the open being a smaller number. Seems to me the open should be a higher word/bit than the close because it has to close the rollers on the log and then open to release the log.

Any help/documentation would be great!

Dan

I suspect some information is missing. I guess there must be an encoder giving the absolute position. There should be a shift register array with 2x4 values (start and end position by 4 sets of rolls) Each set of rolls has an offset position from the photocell. It makes sense that the hold down is "delayed" (higher value then offset) by some pulses, and ditto release some pulses in advance (lower value than offset).

Questing his logic on the internet? Hmmm good employment move, Hmmmm

We are using an encoder simulator based on the two speeds of the VFD that powers the rolls. It ticks every 47ms.

Duckman - i suppose questioning his logic was a bad phrase. However, he does work for me as a contractor we don't have a controls person at the moment so I am doing as much as i know how as i am the superintendent and not the controls person.

Dan

Seems to me the open should be a higher word/bit than the close because it has to close the rollers on the log and then open to release the log.

Click to expand...

If the log is moving "downstream" continuously, then that would be true, if your simulated encoder is tracking downstream movement. However if the log moves back upstream during the debarking, maybe not.