Hello People! This is my first post in the forum, I hope this will help you.

I had to program a valve open system for a filling spinning machine, this is a conventional machine, with an inductive sensor wich detects every valve as a clock sensor, a sensor wich detects the containers at the beginning of the equipment, and an output wich activates a solenoid in order to open the corresponding valve. The original idea was to use a shift register instruction, but, the problem was that I couldn't find a way to extract a bit from an integer (nor DInt, nor Byte, etc.), I still don't know if it's possible.

So, I made a function written in scl language, to achieve the solution of my problem. The code is the follow:

FOR #i := 10 TO 1 BY -1 DO
       "Name_DB".Name_Of_Array[#i] := "Name_DB".Name_Of_Array[#i-1];
END_FOR;

IF "Container_Sensor":P THEN
      "Name_DB".Name_Of_Array[0] := TRUE;
ELSE
      "Name_DB".Name_Of_Array[0] := FALSE;
END_IF;
 
Whereas "i" is a temporal integer variable, "Name_DB".Name_Of_Array is a bit array of 10 elements, and "Container_Sensor" is the name of the input related to the container sensor (:P it's not a face with the tongue outside the mouth, it's the way to call the input even in the middle of the scan, in this case, it wasn't necessary at all).

In another part of the program, there is a clock sensor wich calls in only a scan, to this function. You can make this function in a OB hardware interrupt, linked with the clock sensor.

The function is quite simple, every time the function is called, the FOR cycle, will shift the state of the element number 9 to the 10, from the element 8 to the 9, and so on. And, in the end, the element zero will take the state of the container sensor.

I don't know if this is the best way to solve my problem, at least it works.

I'm sorry for my English

MiloArg

MiloArg

The original idea was to use a shift register instruction, but, the problem was that I couldn't find a way to extract a bit from an integer (nor DInt, nor Byte, etc.), I still don't know if it's possible.

 Dig the forum a little bit and you will find the answer.

MiloArg

The original idea was to use a shift register instruction, but, the problem was that I couldn't find a way to extract a bit from an integer (nor DInt, nor Byte, etc.), I still don't know if it's possible.

 You can do it in three ways:

1. Direct addressing: DB1.DBW0.0to7

2. Indirect Addressing: dynamic connection between two variables

    bit_var := %DB1.DBW0.0to7

   Indirect Addressing

3. Using ANY pointer.

     ANY pointer

good luck choosing the most suitable solution for you. 

Janko

Hi!

If you use S7-1200/1500:

how-in-step-7-tia-portal-do-you-access-the-unstructured-data-types-bit-by-bit-byte-by-byte-or-word-by-word-and-symbolically

Thank you guys! You've been so helpful!!