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MCD Double datatype


Hi Everyone
I'm establishing a communication between TIA PORTAL V14 / PLCSIM V14 and NX11 mechatronic concept desginer using an OPC protocol (KEPware KepserverEX.V6). In the OPC side we have a "DOUBLE" data type. a "Double" is a 64 bits float-point number (CANONICAL DATATYPE 5). Inside MCD we find the same "double" data type. Since I did not find a way to send a 64bits floating-point number from TIAportal to Kepserver I used a standard 32bits float number and it seems to work well. My question is: Is the Double MCD datatype really a 64bits float number, or is it a 32bits float number? Why to call it double instead of just 'float'? Another issue as you can see in the attached picture when i send for exemple a float number with value: 220.0 to MCD and then a I go to runtime inspector even if a change to degrees it does not show me 220 degrees, but it shows me (220 x 1radians) = 12605.071493. It seems to be inverted. Why? Thank you very much ! ! !


Re: MCD Double datatype

Siemens Experimenter Siemens Experimenter
Siemens Experimenter

About double:

  • Yes, MCD double type is 64bit.Below are the range of float/double:
  • But it is compatible with 32bit float without lost precision. If you input float value, it will convert to 64bit double.

 About value unit in MCD:

  • When the external value pass to MCD, MCD suppose it is SI (System International Unit) unit. . So the 220.0 input from OPC is looked as 220.0 radians.