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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.



Re: MCD Double datatype


My team use NX11.0 to build simple mcd electromechanical model. The model works well in mcd using sequence control. When we turns to PLC control(S7 314C-2PnDP, KEP server 4.5 or 6.0)
Boolean signal works well, but  double typed signal was forced turn to int when NX MCD read it from KEP Server. Of course it doesn't work due to MCD position needs a double data.
anyone help us?