And the multiple bits after shift registers

Dear Experts ,

Hope you all are doing well, I need to know about shift registers function at filling machine. There are two digital inputs. 1st one is for filling valve and the 2nd one is for the bottle/container presence at every filling valve. Both are being registered in shift registers. Total number of filling valves is 154. So what I need know is how Both are being AND after the data is registered in the shift registers ? The digital input at filling valves will register all bits to 1 But the 2nd for bottle presence will be zero if there is missing bottle otherwise 1 when bottles are present . I want to get output if there is some missing bottle ? Please tell me how the logic will be ? How the resultant bits of shift registers will be anded ?

Hello,

can you upload the program? Without it is difficult to check what will happen.

Regards

Hay ifte,

U may need to share your program with us 

dear Both , Thanks for your reply and sorry for late from my side, The program has to develop yet, For program/Logic development I am asking that how I will and the resultant bits having length of minimum 154, The bits at filling valves always will be 1 for all and the bit from containers will be also 1 but 0 if container missed or burst etc.

Hope u will help me to develop a logic and get the result for the valve number having no container/bottle.

ifte

Dear Experts ,

Hope you all are doing well, I need to know about shift registers function at filling machine. There are two digital inputs. 1st one is for filling valve and the 2nd one is for the bottle/container presence at every filling valve. Both are being registered in shift registers. Total number of filling valves is 154. So what I need know is how Both are being AND after the data is registered in the shift registers ? The digital input at filling valves will register all bits to 1 But the 2nd for bottle presence will be zero if there is missing bottle otherwise 1 when bottles are present . I want to get output if there is some missing bottle ? Please tell me how the logic will be ? How the resultant bits of shift registers will be anded ?

Hi!

There are many ways to solve this problem. The solution depends on chosen controller and corresponding programming language, as well as on digital input arrangement.

Let's assume you are using STL with S7-300. Being a 32-bit controller, this PLC can not handle 154 bit registers, meaning that you will have to split your filling valves/bottle positions into 16 or 32 bit variables (type WORD or DWORD). You can use binary logic to assign individual bits in those registers based on the actual filling situation.

When both or your registers are filled with data, you can use AW or AD instruction to perform AND operation on them. If all bits are set in both registers, the result will be W#16#FFFF or 65535 in decimal (for data type WORD).

Perform this operation repeatedly until you compare all registers. If all of them are 65535, all bottles are steady and ready.

Hope this helps.

Regards.

@crazyCow - You may want to know about SHRB instruction that is available in the library section (if remembering correctly). As I do not have Step7 Classic, I will not be able to tell you & ifte exactly where the instruction is.

The attached PDF has been generated from TIA Portal.

I think there is no need to have more than one shift register. The one pulse says yes/no and the other gives timing (when to shift). The position in the shift register dictates which action is required.

Dear #DP thanks for your valuable reply, I understand this for shift register & I am able to use this function. But I want to know that after execution spose 153 bottles/valves are filled correctly out of 154 and any one of them is with missing bottle, How I can identify specifically that valve number?, I mean spose valve number 65 has no bottle in one complete revolution , other all are ok filled, How I can get the missing/empty valve exactly ? Hope you have understand my question.

Thanks,

It would be a better idea to use arrays instead of shift registers, then you are able to use your own pointer to all elements.

With the shift register a bit source is declared and may be a DB. Then you can search in the DB for 1 or 0 with a loop. The loop counter will represent the number.

With the array also a bit source is declared and may be a DB. Then you start with your own pointer and when detecting a 1 or 0 you are able to save the actual number while filling the array. You also can search with a loop using a second pointer, if you want.

The best way to help with your problem is an exact description of what you want to do, may be with an incomplete program as example. It is also important to know the used hardware, because the instructions of the plc's are not identical.

Regards, Scorp

Scorp

It would be a better idea to use arrays instead of shift registers, then you are able to use your own pointer to all elements.

That would only make sense when using SCL. Else one would have to resort to indirect addressing in STL.

Maybe i am not very fit with TIA programming or i am using the wrong words, but where is the problem to use an array of bits in FBD or LAD ? When i define a DB1 with the array "Status" and a number "Pointer", then i can use DB1.Status[Pointer] to fill the array. The pointer needs to be reset at start and to increment by 1 while collecting the status bits. Simultaneously it is possible to save the pointer in a second DB depend on the bit (0 or 1). The pointer will represent the number of the valve. The result will be a DB with valve numbers, which has a specific status bit.

Regards, Scorp