Split IEC 61131-3 DINT into two INT variables (PLC structured text)

I want to publish a DINT variable (dintTest) over MODBUS on a PLC to read it with Matlab Instrument Control Toolbox. Turns out, Matlab can read Modbus variables but only INT16. So i want to split the DINT variable into two INT variables in IEC. I found this solution, but this only allows values from +- 0 ... 32767^2:

dintTest := -2;



b := dintTest MOD 32767;

a := dintTest / 32767;

result := 32767 * a + b;



c := DINT_TO_INT(b); // publish over modbus

d := DINT_TO_INT(a); // publish over modbus

What would be the solution for the whole range of DINT?
Thanks!

edit:
I read with a matlab function block in simulink (requires Instrument Control Toolbox):

function Check = MBWriteHoldingRegs(Values,RegAddr)

coder.extrinsic('modbus');

m = modbus('tcpip', '192.169.237.17');

coder.extrinsic('write');

write(m,'holdingregs',RegAddr,double(Values),'int16');

Check = Values;

edited Nov 16 '18 at 15:24

asked Nov 12 '18 at 11:57

Biomusli

By quickly looking, Matlab supports 32 bit variables for modbus. Please check this link under "Specifying Server ID and Precision". So basically you just read the DINT from PLC by giving the starting address of the variable and then read it using read(m,'holdingregs',1,2,'uint32'); or similar. If you need to divide the DINT to two INTs, it is possible with MEMCPY for example. Please provide more information if you need help.
– Quirzo
Nov 14 '18 at 6:25

Thanks, yes, Matlab supports 32 bit variables, but (i guess) with another representation. When reading a variable, the only combination of variables that gives the same result is Matlab 'int16' and IEC 'INT'.
– Biomusli
Nov 15 '18 at 8:27

Could you provide some example how you are actually doing the reading? I haven't used the matlab modbus myself, just normal modbus.
– Quirzo
Nov 15 '18 at 10:55

Yes, I added the matlab function code to the original question.
– Biomusli
Nov 16 '18 at 15:26

Could you try to use DINT at PLC and then write to it with write(m,'holdingregs',RegAddr,Values,'int32'); or something similar?
– Quirzo
Nov 19 '18 at 6:25

|
show 1 more comment

dintTest := -2;



b := dintTest MOD 32767;

a := dintTest / 32767;

result := 32767 * a + b;



c := DINT_TO_INT(b); // publish over modbus

d := DINT_TO_INT(a); // publish over modbus

What would be the solution for the whole range of DINT?
Thanks!

edit:
I read with a matlab function block in simulink (requires Instrument Control Toolbox):

function Check = MBWriteHoldingRegs(Values,RegAddr)

coder.extrinsic('modbus');

m = modbus('tcpip', '192.169.237.17');

coder.extrinsic('write');

write(m,'holdingregs',RegAddr,double(Values),'int16');

Check = Values;

edited Nov 16 '18 at 15:24

asked Nov 12 '18 at 11:57

Biomusli

By quickly looking, Matlab supports 32 bit variables for modbus. Please check this link under "Specifying Server ID and Precision". So basically you just read the DINT from PLC by giving the starting address of the variable and then read it using read(m,'holdingregs',1,2,'uint32'); or similar. If you need to divide the DINT to two INTs, it is possible with MEMCPY for example. Please provide more information if you need help.
– Quirzo
Nov 14 '18 at 6:25

Thanks, yes, Matlab supports 32 bit variables, but (i guess) with another representation. When reading a variable, the only combination of variables that gives the same result is Matlab 'int16' and IEC 'INT'.
– Biomusli
Nov 15 '18 at 8:27

Could you provide some example how you are actually doing the reading? I haven't used the matlab modbus myself, just normal modbus.
– Quirzo
Nov 15 '18 at 10:55

Yes, I added the matlab function code to the original question.
– Biomusli
Nov 16 '18 at 15:26

Could you try to use DINT at PLC and then write to it with write(m,'holdingregs',RegAddr,Values,'int32'); or something similar?
– Quirzo
Nov 19 '18 at 6:25

|
show 1 more comment

dintTest := -2;



b := dintTest MOD 32767;

a := dintTest / 32767;

result := 32767 * a + b;



c := DINT_TO_INT(b); // publish over modbus

d := DINT_TO_INT(a); // publish over modbus

What would be the solution for the whole range of DINT?
Thanks!

edit:
I read with a matlab function block in simulink (requires Instrument Control Toolbox):

function Check = MBWriteHoldingRegs(Values,RegAddr)

coder.extrinsic('modbus');

m = modbus('tcpip', '192.169.237.17');

coder.extrinsic('write');

write(m,'holdingregs',RegAddr,double(Values),'int16');

Check = Values;

edited Nov 16 '18 at 15:24

asked Nov 12 '18 at 11:57

Biomusli

dintTest := -2;



b := dintTest MOD 32767;

a := dintTest / 32767;

result := 32767 * a + b;



c := DINT_TO_INT(b); // publish over modbus

d := DINT_TO_INT(a); // publish over modbus

What would be the solution for the whole range of DINT?
Thanks!

edit:
I read with a matlab function block in simulink (requires Instrument Control Toolbox):

function Check = MBWriteHoldingRegs(Values,RegAddr)

coder.extrinsic('modbus');

m = modbus('tcpip', '192.169.237.17');

coder.extrinsic('write');

write(m,'holdingregs',RegAddr,double(Values),'int16');

Check = Values;

matlab modbus plc st

edited Nov 16 '18 at 15:24

asked Nov 12 '18 at 11:57

Biomusli

edited Nov 16 '18 at 15:24

asked Nov 12 '18 at 11:57

Biomusli

edited Nov 16 '18 at 15:24

asked Nov 12 '18 at 11:57

Biomusli

asked Nov 12 '18 at 11:57

Biomusli

asked Nov 12 '18 at 11:57

Biomusli

By quickly looking, Matlab supports 32 bit variables for modbus. Please check this link under "Specifying Server ID and Precision". So basically you just read the DINT from PLC by giving the starting address of the variable and then read it using read(m,'holdingregs',1,2,'uint32'); or similar. If you need to divide the DINT to two INTs, it is possible with MEMCPY for example. Please provide more information if you need help.
– Quirzo
Nov 14 '18 at 6:25

Thanks, yes, Matlab supports 32 bit variables, but (i guess) with another representation. When reading a variable, the only combination of variables that gives the same result is Matlab 'int16' and IEC 'INT'.
– Biomusli
Nov 15 '18 at 8:27

Could you provide some example how you are actually doing the reading? I haven't used the matlab modbus myself, just normal modbus.
– Quirzo
Nov 15 '18 at 10:55

Yes, I added the matlab function code to the original question.
– Biomusli
Nov 16 '18 at 15:26

Could you try to use DINT at PLC and then write to it with write(m,'holdingregs',RegAddr,Values,'int32'); or something similar?
– Quirzo
Nov 19 '18 at 6:25

|
show 1 more comment

By quickly looking, Matlab supports 32 bit variables for modbus. Please check this link under "Specifying Server ID and Precision". So basically you just read the DINT from PLC by giving the starting address of the variable and then read it using read(m,'holdingregs',1,2,'uint32'); or similar. If you need to divide the DINT to two INTs, it is possible with MEMCPY for example. Please provide more information if you need help.
– Quirzo
Nov 14 '18 at 6:25

Thanks, yes, Matlab supports 32 bit variables, but (i guess) with another representation. When reading a variable, the only combination of variables that gives the same result is Matlab 'int16' and IEC 'INT'.
– Biomusli
Nov 15 '18 at 8:27

Could you provide some example how you are actually doing the reading? I haven't used the matlab modbus myself, just normal modbus.
– Quirzo
Nov 15 '18 at 10:55

Yes, I added the matlab function code to the original question.
– Biomusli
Nov 16 '18 at 15:26

Could you try to use DINT at PLC and then write to it with write(m,'holdingregs',RegAddr,Values,'int32'); or something similar?
– Quirzo
Nov 19 '18 at 6:25

By quickly looking, Matlab supports 32 bit variables for modbus. Please check this link under "Specifying Server ID and Precision". So basically you just read the DINT from PLC by giving the starting address of the variable and then read it using read(m,'holdingregs',1,2,'uint32'); or similar. If you need to divide the DINT to two INTs, it is possible with MEMCPY for example. Please provide more information if you need help.
– Quirzo
Nov 14 '18 at 6:25

Thanks, yes, Matlab supports 32 bit variables, but (i guess) with another representation. When reading a variable, the only combination of variables that gives the same result is Matlab 'int16' and IEC 'INT'.
– Biomusli
Nov 15 '18 at 8:27

Could you provide some example how you are actually doing the reading? I haven't used the matlab modbus myself, just normal modbus.
– Quirzo
Nov 15 '18 at 10:55

Yes, I added the matlab function code to the original question.
– Biomusli
Nov 16 '18 at 15:26

Could you try to use DINT at PLC and then write to it with write(m,'holdingregs',RegAddr,Values,'int32'); or something similar?
– Quirzo
Nov 19 '18 at 6:25

|
show 1 more comment

1 Answer
1

active

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votes

I would better split DINT to 2 WORD

VAR

    diInt: DINT := -2;

    dwTemp: DWORD;

    w1: WORD;

    w2: WORD;

END_VAR





dwTemp := DINT_TO_DWORD(diInt);



w1 := DWORD_TO_WORD(dwTemp);

w2 := DWORD_TO_WORD(SHR(dwTemp, 16));

And then I could build it back in matlab.

The point here is not using mathematic but bit masks.

answered Nov 19 '18 at 7:36

Sergey Romanov

1,68921628

add a comment |

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1 Answer
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1 Answer
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oldest

votes

I would better split DINT to 2 WORD

VAR

    diInt: DINT := -2;

    dwTemp: DWORD;

    w1: WORD;

    w2: WORD;

END_VAR





dwTemp := DINT_TO_DWORD(diInt);



w1 := DWORD_TO_WORD(dwTemp);

w2 := DWORD_TO_WORD(SHR(dwTemp, 16));

And then I could build it back in matlab.

The point here is not using mathematic but bit masks.

answered Nov 19 '18 at 7:36

Sergey Romanov

1,68921628

add a comment |

I would better split DINT to 2 WORD

VAR

    diInt: DINT := -2;

    dwTemp: DWORD;

    w1: WORD;

    w2: WORD;

END_VAR





dwTemp := DINT_TO_DWORD(diInt);



w1 := DWORD_TO_WORD(dwTemp);

w2 := DWORD_TO_WORD(SHR(dwTemp, 16));

And then I could build it back in matlab.

The point here is not using mathematic but bit masks.

answered Nov 19 '18 at 7:36

Sergey Romanov

1,68921628

add a comment |

I would better split DINT to 2 WORD

VAR

    diInt: DINT := -2;

    dwTemp: DWORD;

    w1: WORD;

    w2: WORD;

END_VAR





dwTemp := DINT_TO_DWORD(diInt);



w1 := DWORD_TO_WORD(dwTemp);

w2 := DWORD_TO_WORD(SHR(dwTemp, 16));

And then I could build it back in matlab.

The point here is not using mathematic but bit masks.

answered Nov 19 '18 at 7:36

Sergey Romanov

1,68921628

I would better split DINT to 2 WORD

VAR

    diInt: DINT := -2;

    dwTemp: DWORD;

    w1: WORD;

    w2: WORD;

END_VAR





dwTemp := DINT_TO_DWORD(diInt);



w1 := DWORD_TO_WORD(dwTemp);

w2 := DWORD_TO_WORD(SHR(dwTemp, 16));

And then I could build it back in matlab.

The point here is not using mathematic but bit masks.

answered Nov 19 '18 at 7:36

Sergey Romanov

1,68921628

answered Nov 19 '18 at 7:36

Sergey Romanov

1,68921628

answered Nov 19 '18 at 7:36

Sergey Romanov

1,68921628

answered Nov 19 '18 at 7:36

Sergey Romanov

1,68921628

add a comment |

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