How to use memorylocation %m

Codesys V2.3 🇬🇧
sarathbabu
2012-10-09
2012-10-10

  • sarathbabu - 2012-10-09

    Hi,
    Can any give me an example of how %M is used in the program,means where I have to declare this ?

    Thanks

     

  • shooter - 2012-10-09

    same place as you would do with the in and outputs

    I tend to put them all global so i can see and change them anywhere.

     

  • jzhvymetal - 2012-10-10

    They can declared anywhere in declaration. Below are examples

    myBool AT %MX0.0 : BOOL; //Boolean Type
    myInput AT %IX0.0 : BOOL;
    myOut AT %QX0.0 : BOOL;

    myByte AT %MB0 : BYTE; //Byte Type
    mySINT AT %MB0 : SINT;
    myUSINT AT %MB0 : USINT;
    myByteArary AT %MB0 : ARRAY[0..10] OF BYTE;

    myWORD AT %MW0 : WORD; //16 bit types
    myINT AT %MW0 : INT;
    myUINT AT %MW0 : UINT;
    myWordArary AT %MW0 : ARRAY[0..10] OF WORD;

    myDWORD AT %MD0 : DWORD; //32bit Types
    myDINT AT %MD0 : DINT;
    myUDINT AT %MD0 : UDINT;
    myReal AT %MD0 : REAL;
    myDwordArray AT %MD0 : ARRAY[0..10] OF DWORD;

    mySTRING AT %MB0 : STRING; //STRING

     

  • sarathbabu - 2012-10-10

    Hi,
    Thanks for the reply.

    What is the difference between

    sarath:array [1..10] of DWORD; and myDwordArray AT %MD0 : ARRAY[0..10] OF DWORD;

    Is it just that %MD0 is known location?

    Thanks

     

  • shooter - 2012-10-10

    yes it is a known location , and you when having several PLC in a communication like the old MODBUS you can ask any plc for a memory location and get its results.
    Many HMI displays work with these MARKERS.

     

  • jzhvymetal - 2012-10-10

    Maybe this will help. This is an excel sheet with how the memory is aligned. Like Shooter said not all PLC/HMI align the memory the same. This sheet is based off SoMachine/Vijeo hardware built by SE.

    SoM Modbus Table.xls [418.5 KiB]

     

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