Siemens 500 NIM User Manual

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NIM Primitives
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SIMATIC TIWAY I Series 500 NIM User Manual
Primitive Structure and Operation (continued)
The upload and download formats will always be identical, i.e., data that is
received from an upload request will be sent unmodified (in the same order
and format) to the attached device during download.
You cannot write data or change the attached device operating mode during
an upload or download request; however, you can continue to read data. If
an attempt is made to write data or change the operating mode, an
exception code will be returned. Also, you cannot initiate another upload or
download request until the previous request is complete. The native and
packed native Primitives are not allowed in upload or download mode if
they contain a write command.
Program transfer procedures are slightly different from normal operations
in that the NIM and the controller must change operating states to
participate in the data transfer. Program upload and download are mutually
exclusive and cannot occur simultaneously.  Only one generic load operation
may be executed at any given time.