Copy data between different data types in Unity

[EMurphy]

I am using READ_VAR to read data from a slave device.  It returns data as an Array of INTs.  Using Function Block or Structured Text is there a way to copy this data to a DDT so that I don't have to extract the data register by register.  I am currently assigning the Array and the DDT to the same address, but I have to turn off the Overlapping Address warnings.  Wondering if there is a programmatic method?

Thanks

[Anonymous user]

Dear colleagues, I'm also interested in this topic, are there SMART solution for that?

[JerryBartlemay]

There really isn't a "smart" way to do this.  I would suggest using a DFB with structured text or FBD using moves to take the data from the INT array and move into the appropriate elements of the DDT you create.  This would eliminate the issues you have with memory word alignment on REALs and DINTs.  

Even if you were using a Modbus TCP DTM on a NOC module, it is not always possible to create a DDT items within the DTM instance because of this alignment constraint.  In that case, a DFB to do the moves is still the best answer.

Of course, you could do those moves in a section of logic, but even for a one-off usage, creating a DFB encapsulates the code and simplifies your base logic.

[Juan · Accepted solution]

Hi,

Use the extract function to copy memory zones.

EXTRACT (SRC := (*ANY*),
                  SRC_NELEM := (*UDINT*),
                  SRC_POS := (*UDINT*),
                  DST_POS := (*UDINT*),
                  CPY_NELEM := (*UDINT*),
                  DST => (*ANY*),
                  ERR => (*INT*));

Regards,

Juan