Siemens 500 NIM - Manual (Page 57)

NIM Primitives 4-4 SIMATIC TIWAY I Series 500 NIM User Manual
4.3 Primitive Structure and Operation
A Primitive consists of multiple fields that specify the Primitive’s length and
function, type and location of data to be accessed, and data to be
transferred. In TIWAY I, a Primitive forms the information field of an
HDLC Information frame (I) or Unnumbered Information frame (UI) if
HDLC operation is selected. If X.25 operation is selected, the Primitive is
contained in the User Data field of an X.25 Data Packet.
!
WARNING
When you write to memory, you may be directly affecting the process which is
under control by the programmable controller.
Unexpected alterations to process operation could cause death or serious
injury to personnel and/or damage to equipment.
Before you make changes in memory, be certain that the changes which result
in the controlled process will not endanger any personnel or equipment.