Conveyor Control - Window Reservation

If that is all there is to it then...

Why keep track of windows. If a bag is waiting and there is a space on the conveyor then let the bag go. Do it first come first served.

First question is.. which is better... absolute or incremental encoders?

Either an incremental or absolute encoder will create the windows, but how do you want to track the actual window position? Personally I would use an incremental encoder. You can actually use an incremental encoder to both create the window AND accuractly track the window position.

Lets say each window is 20 counts long and Check in Counter 5 is at the encoder count position 250, but you might want to signal Check In 5 to drop the bag when the window reaches 230, or 240 etc.. So in short the incremental encoder will allow more flexability in the final setup.

Regarding assigning windows. You maybe should assign windows to the counters on a 1st come 1st served basis. OR you might find it necessary to priortize them by which bag has to get to what gate in time for it to make it's flight. If the bag at check in 5 has to go to a flight in 5 minutes, but the bag in check in 1 leaves in one hour, you would want the bag in 5 on the conveyer before the one check in 1.

Sequence problem, shift register or FIFO???

Hello,all. I am now doing a project which is almost the same as appleplc07's project. We have 18 checkin counters. Once the baggage is moved to the induction conveyor, the control system will look for available space on the take away conveyor to create a virtual window. The virtual window is detected by a sensor installed 1m upstream for every counter. And we want to release the baggage once a 1.75m window is created. All the counters have equal opportunity to create the virtual window, the induciton of baggage onto the wirtual window is based on 1st com 1st served basis.
I have read some related topics but still not very sure about the method to use. some people say should use shift registers while others say use FIFO. I am using siemens step7 and quite new to this software, which one shall i choose? how to apply to my project? if use shift register, shall i use one shift register for all counters or one register one counter? Is FIFO useful to my project?

Thanks a lot for the help. Waiting for your reply.

appleplc07 said:

I did look at the Denver air port project and luckily my scope is not as big as that. ...

Click to expand...

Denver Airport, probably the biggest disaster ever in airport systems... DO NOT COPY THESE!!!

Cost the airport authorities millions and the scalp of a major integrator.

Peter Nachtwey said:

Why keep track of windows. If a bag is waiting and there is a space on the conveyor then let the bag go. Do it first come first served.

Click to expand...

That doesn't work Peter, at busy times bags are continously injected onto the main conveyor. The poor ones at the end never get injected. Operators get frustrated and push bags onto the conveyors which ends up with double bags and problems down-line.

Its been very interesting seeing how people believe these work, I presume people realise I work in airports by now and have designed these things.

Two things, it hurts when people say we don't care about the bags and the sortation is more complex than the check-ins, with all the tracking, reading of barcodes, routing, alternative routes when sections go down, etc etc....

:nodi:

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