Siemens SINUMERIK 840D sl Function Manual page 857

Programming basic frames
Basic frames can be read and written via the part program and via the OPI by operator
actions and by the PLC. However, only data management frames can be written by the OPI.
2.4.5.4 NCU global basic frames $P_NCBFR[n]
The number of global basic frames can be configured via the machine data:
MD18602 $MN_MM_NUM_GLOBAL_BASE_FRAMES (number of global, basic frames
(SRAM))
There are a maximum of 16 global basic frames. All basic frames are stored as fields.
System variable $P_NCBFR[n] can be used to read and write the basic frame field elements.
While writing a basic frame field element, the chained total frame is not activated. Instead,
the activation takes place only after a G500,G54..G599instruction is executed. If the
modified frame is to be active in every channel of the NCU, every channel must execute a
G500,G54..G599instruction. The variable is used primarily for storing write operations to the
basic frame on HMI or PLC. These frame variables are saved by the data backup.
Current NCU global basic frames $P_NCBFRAME[n]
System variable $P_NCBFRAME[n] can be used to read and write the current global basic
frame field elements. The resulting total basic frame is calculated by means of the write
process in the channel. The modified frame is activated only in the channel in which the
frame was programmed. If the frame is to be modified for all channels of an NCU,
$P_NCBFR[n] and $P_NCBFRAME[n] must be written simultaneously. The other channels
must then activate the frame, e.g., with G54. Whenever a basic frame is written, the
complete basic frame is calculated again.
Basic logic functions: Axes, coordinate systems, frames (K2)
Function Manual, 11/2006, 6FC5397-0BP10-2BA0
Detailed description
2.4 Frames
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