DEAR EVERYONE,

I WANT TO KNOW CAN WE CONVERT A REAL NUMBER INTO POINTER FORMAT

FOR EXAMPLE,SAY CONTENT OF DB1.DBD4 WHICH IS 1.5 ,INTO POINTER

FORMAT .IF IT IS POSSIBLE HOW IT IS DONE ,ACTUALLY ,I WOULD LIKE USE THIS FOR

INPUT/OUTPUT MAPPING WITH DB ADDRESS.

THANKS,SAMIR

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Split from How is an ANY pointer structured?.

Samir,

SAMIRKM

DEAR EVERYONE,

I WANT TO KNOW CAN WE CONVERT A REAL NUMBER INTO POINTER FORMAT

FOR EXAMPLE,SAY CONTENT OF DB1.DBD4 WHICH IS 1.5 ,INTO POINTER

FORMAT .IF IT IS POSSIBLE HOW IT IS DONE ,ACTUALLY ,I WOULD LIKE USE THIS FOR

INPUT/OUTPUT MAPPING WITH DB ADDRESS.

THANKS,SAMIR

It will be most helpful if you expand on what you want this for. For me it is not clear. The application, software used and controller used also carry weight in the answer..

The any pointer for DB1.DBD4 is   P#DB1.DBX4.0 BYTE 4

The fact that the bits in the 4 bytes are interpreted as REAL play no role for the any pointer.

Next guess - if you want to split have "1.5"  be converted as "I1.5" then that is another matter. The structure of an any pointer will need to be used.

User smiffy has done this type of decomposition-recomposition on several posts. Please find that if the PDF provided in this topic does not help you enough.

Then split the 1.5 in two numbers 1 and 5 before applying these numbers into the any pointer.

So please be specific on where you require help. Also why / which purpose.

DEAR SIR,

I WANT TO DO DI MAPPING ,FOR THAT ,I CREATED DB5(REAL_DB) WHICH CONTAINS

DI ADDRESS(I.E INITIALIZED VALUE),AND ANOTHER DB4(WHICH WILL BE USED IN PROGRAM)

INSTEAD OF DIRECT DI INPUT.AND IN FC3 MAPPING PROGRAM IS WRITTEN.

BUT MY PROGRAM IS NOT WORKING.I HAVE UPLOADED THE SAMPLE PROGRAMME

PLEASE HELP ME AFTER GOING THROUGH IT.

THANKS ,

SAMIR

Thank you for your reply. I now understand what you are aiming to do.

Sadly I have no ability (no Step7 V5.x) to look at your program. Hopefully someone else will step forward.

SAMIRKM

DEAR SIR,

I WANT TO DO DI MAPPING ,FOR THAT ,I CREATED DB5(REAL_DB) WHICH CONTAINS

DI ADDRESS(I.E INITIALIZED VALUE),AND ANOTHER DB4(WHICH WILL BE USED IN PROGRAM)

INSTEAD OF DIRECT DI INPUT.AND IN FC3 MAPPING PROGRAM IS WRITTEN.

BUT MY PROGRAM IS NOT WORKING.I HAVE UPLOADED THE SAMPLE PROGRAMME

PLEASE HELP ME AFTER GOING THROUGH IT.

THANKS ,

SAMIR

Hi Samir,

Can you elaborate your requirement, A Small example will do.  

Harish G

 Hi Samir,

Can you elaborate your requirement, A Small example will do.  

HMI  ->  sensor7: REAL#1.5   ->  [PLC code]  ->  sensor7 := I1.5;

#dP

 

Harish G

 Hi Samir,

Can you elaborate your requirement, A Small example will do.  

 

HMI  ->  sensor7: REAL#1.5   ->  [PLC code]  ->  sensor7 := I1.5;

 

 Sorry still not clear,

If I select Sensor 7 which has Value  in Real format 1.5  same for other equipment So do you want to show  I 1.5 Digital Status on Screen?

Hello.

Harish G

Sorry still not clear,

If I select Sensor 7 which has Value  in Real format 1.5  same for other equipment So do you want to show  I 1.5 Digital Status on Screen?

The working principle is that you have a generic machine that has program functionality for every possible functionality. A configuration tool is used to tell the machine which functionality is active and how this functionality is linked to the outside world.

For example a conveyor line consisting of one motor and one sensor. The generic program is told to adapt itself for 8 conveyors (without program changes from the Engineer) . The next step is telling the machine which outputs (Q2.0 - Q2.7) and inputs(I2.0 to I2.7) are used.

Internal to the PLC there is a look-up table doing mapping between functionality (sensor7) to the actual sensor (I2.6) {_{sorry now different that I1.5 of earlier}}.

The advantage is that the control design engineer only need to design a super generic algorithm that can handle most cases. Then a junior or technician selects the parts and amounts needed for the process. Customization is done by configuration and not by programming.

The bad side is that the mapping of functionality to physical IO utilizes indirect addressing that makes the through-put of the machine less effective. An alternative is to have PC code to generate PLC code.

So Samir os looking for a way to give a code block a real number and the block returns the input or output state that corresponds to the real number.

BR

DEAR #DP,

WHAT I AM LOOKING FOR IS:-

SAY I1.5 IS ASSIGNED TO DB4.DBX0.0

A I 1.5

=DB4.DBX0.0

NOW IF MY CHANNEL NUMBER I 1.5 IS FAULTY ,THEN I REPLACED WITH I 2.6

NOW THE LOGIC IS:-

A I 2.6

=DB4.DBX0.0

I AM WRITING A STANDARD LOGIC FOR THAT ONLY ,WHICH I UPLOADED IN MY SAMPLE PROGRAM.

CAN U HELP ME TO GET MY CODES RIGHT.

THANKS,

SAMIR

@Samir: what is not working in your code as expected by you is this: 

L REAL#1.5

T someDWORDVariable

A I[someDWORDVariable]

To understand why it is not working you need to know 2 things.

1) The format of the addresses in S7:

byte.bit notation (e.g. p#1.5) is coded on 32 bits (dword) as follows:

0000 0000 0000 0bbb bbbb bbbb bbbb bxxx - where bbbb bbbb bbbb bbbb is natural binary coded byte address and xxx is bit address.

So address p#1.5 looks like this:

0000 0000 0000 0000 0000 0000 0000 1101 

 2) The format of the real numbers which is according to the IEEE754 binary32.

So the REAL#1.5 looks like this:

0011 1111 1100 0000 0000 0000 0000 0000

As you may notice they have nothing in common.

To obtain address you should extract integer and fraction parts of your REAL number and then assemble a pointer out of them.

Personally, I'd use integer data type to "code" the address in a human-readable format instead of REAL, i.e. p#1.5 would be stored as 15. Then it's less effort to convert it into a proper S7 address.