Shift registers

bb1fit

Member
Join Date
May 2006
Location
Midwest
Posts
32
Ok, I am new at this, doing this strictly at home. I am doing the bottle simulation, and am having trouble making the right bottles(large ones) drop only. What my biggest problems is I guess is I don't understand the shift register logic...how do I figure the right bit number from my BSL instruction to divert only the large bottles? Am using LS2(large bottle limit switch) with my BSL in series to initiate the drop gate. Thanks for anyone in advance for any help. Understanding shift registers will probably be a big plus to me figuring this thing out.
 
I would say...

If you are using Bit-Shift Registers...

Use TWO shift registers... each synchronized with the other.

You need to know the size... and the presence!

Use one register to monitor the presence of all bottles.

Then use the other to monitor the size.

If Reg-A = 1 then Bottle present...
If Reg-B = 0 then Bottle is Small.
If Reg-B = 1 then Bottle = Large.

If you are using Word-Shift Registers... the Word could contain both the presence and the stature!
 
bb1fit,

Remember that the bit-shift register is an attempt to mimic the physical movement of the bottles. When a bottle moves a certain distance on the conveyor, a bit should shift 1 position in the PLC memory. To figure the right bit number from the LS2, simply count the number of bottles (and empty bottle positions) on the conveyor between the LS2 and the Divert Gate. In real-life systems, I set the encoder to pulse every 1", and then use a 100-foot tape to measure the distance between the trigger point and the diverter gate trip point.

Because your memory Words are 16 bits, count the bottles like this, starting with B3:4/0 at LS2 (where a 1 bit is shifted into the BSL if the bottle is Tall), then B3:4/1, B3:4/2, and so on until B3:4/15, then you go to B3:5/0, B3:5/1, B3:5/2, B3:5/3, B3:5/4, B3:5/5 and you are there! This same method can be applied to "measure" the distance between ANY BSL trigger point and the various action points of the Bottle Fill system.

To get an idea of how the BSL works, Run the program, start the conveyor, and arrange your windows so you can see the LS2 limit switch and also your rung that contains the BSL. Set the so-called "Scans" speed at about 50%, so that you can see the action. Now RIGHT-click on the BSL instruction and select "Go to Data Tables". Look at B3:4/0 and watch as a tall bottle goes under LS2. You will see a "1" pop up in B3:4/0. Each time the encoder pulses, that 1 will move 1 position left, finally wrapping around to B3:5/0 and dropping off at B3:5/15 (if you have your BSL Length parameter set to 32).
 
Last edited:
bb1fit said:
Ok, I am new at this, doing this strictly at home. I am doing the bottle simulation, and am having trouble making the right bottles(large ones) drop only. What my biggest problems is I guess is I don't understand the shift register logic...how do I figure the right bit number from my BSL instruction to divert only the large bottles? Am using LS2(large bottle limit switch) with my BSL in series to initiate the drop gate. Thanks for anyone in advance for any help. Understanding shift registers will probably be a big plus to me figuring this thing out.

Help is on it's way

http://www.mrplc.com/kb/index.php?page=index_v2&id=71&c=12
http://forums.mrplc.com/index.php?download=353
http://forums.mrplc.com/index.php?download=350
 
Thanks folks....great replies. Hats off to Lancie....nice explanation. I truly appreciate it.

And Mickey, I tried to dl those files earlier, found them in another thread, but all said zip file corrupt trying to open them. Thanks much anyway.

This is a great resource here, hope folks don't get too tired of answering my questions. :)
 
bb1fit said:
Thanks folks....great replies. Hats off to Lancie....nice explanation. I truly appreciate it.

And Mickey, I tried to dl those files earlier, found them in another thread, but all said zip file corrupt trying to open them. Thanks much anyway.

This is a great resource here, hope folks don't get too tired of answering my questions. :)

Hmmmmm? I just downloaded both and they worked for me.
 

Similar Topics

Good Morning , I need to use a shift register to keep track of good and bad parts . As a rough draft I'm using 300 bits. When the 1's and 0's...
Replies
4
Views
1,770
Any ideas using"Shift Registers"for Vision Failures on long conveyors for Dump Gate? Good Morning , We are starting a quality program...
Replies
15
Views
3,786
Hi folks, this is for you Shift Register guys. Can anyone see anything fundamentally wrong with the attached code? i've used this bit of code...
Replies
4
Views
2,287
Good Evening,Have any of you fellows have experience in programming a DW Shift register ? I need too track broken pins on a accumulator and stop...
Replies
1
Views
1,387
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...
Replies
4
Views
2,067
Back
Top Bottom