UNION

2020-02-27T14:10:46.793000Z

For this very reason I wish 3s would allow BIT as array type then you would be able to do the following

TYPE UNION_BITS_WORD :
UNION
   xBit : ARRAY[0..15] OF BIT;
   wWord : WORD;
END_UNION
END_TYPE

Since BIT is not allowed as a base type of an array this would not work. Can someone at 3s add a request?

UNION

2020-02-27T14:10:46.367000Z

Just for your information (not the best solution, but just as information what is possible):

You could create a structure of BITS (REGARD THE FACT THAT THEY ARE BIT AND NOT BOOL:

TYPE STR_BITS :
STRUCT
   x1 : BIT;
   x2 : BIT;
   x3 : BIT;
   x4 : BIT;
   x5 : BIT;
   x6 : BIT;
   x7 : BIT;
   x8 : BIT;
   x9 : BIT;
   x10 : BIT;
   x11 : BIT;
   x12 : BIT;
   x13 : BIT;
   x14 : BIT;
   x15 : BIT;
   x16 : BIT;
END_STRUCT
END_TYPE

Then you can create a UNION containing the structure and the WORD:

TYPE UNION_BITS_WORD :
UNION
   strBits : STR_BITS;
   wWord : WORD;
END_UNION
END_TYPE

Now it is possible to use the union with BIT/WORD access:

PROGRAM Main
VAR
   u1 : UNION_BITS_WORD;    // Declaration of a union variable
   xBool1: BOOL;         // just a bool
   xBool5: BOOL;         // just a bool
END_VAR
// Assign some value to the word of the union
u1.wWord := 16#F0F0;
// Get the bit value from the structure of bits and assign it to a BOOL
xBool1 := u1.strBits.x1;
xBool5 := u1.strBits.x5;

UNION

2020-02-27T14:10:45.118000Z

Originally created by: ph0010421

Thank you both for the quick answers.
Have a good weekend.

Paul

UNION

2020-02-27T14:10:44.703000Z

Originally created by: scott_cunningham

BOOLs are stored as BYTE size in CoDeSys. Use bit level access as described by ndzied1. Either the util library or oscat.de library has pack/unpack functions you can use if you need to break apart a bit coded variable.

UNION

2020-02-27T14:10:44.353000Z

depending on what you need, you may not need the union.

You can always use the dot notation to access the bits in a word.

MyWord: WORD;
Bit0 := MyWord.0;
Bit1 := MyWord.1;

Not sure if this works with INT type but easy to try in simulation mode.

UNION

2020-02-27T14:10:43.350000Z

Originally created by: ph0010421

Hello
How can I 'UNION' an INT with an ARRAY[0..15] of BOOL

Each 'BOOL' seems to take 1 byte...
Bit 0 is 1
Bit 1 is 256
...

Thanks

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