Hi all,

till now we always created the PlcFieldHandler and PlcValueHandlers in the 
Driver code statically.

Now with the updated ADS driver we have some completely new possibilities:

  *   We can check if a tag exists before executing the query
  *   We can check the type and structure of values we want to write before 
sending them to the PLC
  *   We can start using some fancy array notation which we can validate the 
query before sending the request.

The only problem I currently have, it that the FieldHandler and ValueHandler 
are both created detached from the Connection, where the information is present.

So, I would like to change that the Connection is responsible of creating the 
PlcValueHandler and PlcValueHandler.


With this we could even do crazy stuff like:

  *   In S7 give an error warning if the type of S7 doesn’t support the 
datatype, that the user wanted to use?
  *   Possibly rewrite fields, if we’re using an incompatible S7 type (Like if 
I’m on a S7-1200 and want to read a LINT, which the 1200 doesn’t support), then 
we could replace this with a 2-element array of DINT and still support 
datatypes the device itself doesn’t.
  *   We could provide an error if someone wants to use the S7 driver 
subscription API with a PLC, that doesn’t support that.
  *   … I probably could go on forever ;-)


What do you folks think?


Chris

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