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First, I'm looking for a way to do mathematical power (i.e. x raised to the power of y), but I can't seem to find a way to do it. Is there an operator or function in Codesys that can do it? I've tried scanning the documentation and libraries to no avail.
Secondly, I've been looking for a way to merge two 16-bit ints into a real. This is a surprisingly common operation as sensors/meters tend to store data in real form but accessible over modbus through two 16-bit registers. Again, I can't find a way to do this.
Finally, I'm not sure how to accessing inputs and outputs on PLCs through Codesys. Is there some documentation on this topic? Preferably without having to map I/O to variables since this just wastes time with our current system.
Any help, samples or even direction would be great.
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The EXPT function raises one variable to the power of another.
One way to do this is to define a union (DUT) as shown below.
TYPEMySignalType:UNION
  RSignal  :REAL;   Â
  ISignal   :ARRAY[0..1]OFINT;END_UNIONEND_TYPE
RSignal and ISignal occupy the same memory space so you could access the data as follows:
VAR
  A  :MySignalType;
  B  :REAL;
  C  :INT;
  D  :INT;   Â
END_VARA.RSignal:=B;Â Â Â Â //PutsomerealdataintotheunionC:=A.ISignal[0];Â Â //GetdataoutofunionastwoINTsD:=A.ISignal[1];
It's amazing how well hidden that operator is. It's not even listed on the operators page in the manual!
Regarding the real, that seems very useful. I will probably still have to be wary regarding endianness, although I'm not sure how to detect that in ST. Were it C or C++, it would be another matter, though.
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Hi,
A couple of questions.
First, I'm looking for a way to do mathematical power (i.e. x raised to the power of y), but I can't seem to find a way to do it. Is there an operator or function in Codesys that can do it? I've tried scanning the documentation and libraries to no avail.
Secondly, I've been looking for a way to merge two 16-bit ints into a real. This is a surprisingly common operation as sensors/meters tend to store data in real form but accessible over modbus through two 16-bit registers. Again, I can't find a way to do this.
Finally, I'm not sure how to accessing inputs and outputs on PLCs through Codesys. Is there some documentation on this topic? Preferably without having to map I/O to variables since this just wastes time with our current system.
Any help, samples or even direction would be great.
The EXPT function raises one variable to the power of another.
One way to do this is to define a union (DUT) as shown below.
RSignal and ISignal occupy the same memory space so you could access the data as follows:
Related
Talk.ru: 1
Thanks for the reply!
It's amazing how well hidden that operator is. It's not even listed on the operators page in the manual!
Regarding the real, that seems very useful. I will probably still have to be wary regarding endianness, although I'm not sure how to detect that in ST. Were it C or C++, it would be another matter, though.
Dears.
I think that inside the union B has to be lint. If you put lreal, it takes 13 lasts bits as exponent.
If you have the number as lint it is easy to convert to lreal