Siemens SINUMERIK 840D sl Function Manual page 733

$P_CHBFRAME[<n>] (active channel-specific basic frames)
System variable $P_CHBFRAME[<n>] can be used to read and write the active channel-
specific basic frames. When writing an active channel-specific basic frame, the new values
take effect immediately through the recalculation of the active complete basic frame
$P_ACTBFRAME.
System variables for compatibility reasons
$P_UBFR (first channel-specific basic frames of the data management)
The system variable is retained for reasons of compatibility, although it is redundant for the
$P_CHBFR[0] variables.
The basic frame with field device 0 is not activated simultaneously when writing to the
predefined $P_UBFR variable, but rather activation only takes place on execution of a G500,
G54,.G599 command. For NCU-global frames, the changed frame only becomes active in
those channels of the NCU, which execute a G500, G54..G599 command. The variable is
used primarily for storing write operations to the basic frame on HMI or PLC. The variable can
also be read and written in the program.
$P_UBFR is identical to $P_CHBFR[0]. One basic frame always exists in the channel by
default, so that the system variable is compatible with older versions. If there is no channel-
specific basic frame, an alarm is issued at read/write: "Frame: Statement not permitted" is
output on a read or write access.
$P_BFRAME (first active channel-specific basic frame)
The system variable is retained for reasons of compatibility, although it is redundant for the
$P_CHBFRAME[0] variables.
The predefined frame variable $P_BFRAME can be used to read and write the current basic
frame with the array index 0, which is valid in the channel, in the part program. The written
basic frame is immediately included in the calculation. In the case of NCU-global settable
frames, the modified frame acts only in the channel in which the frame was programmed. If
the frame is to be modified for all channels of an NCU, $P_UBFR and $P_BFRAME must be
written simultaneously. The other channels must then activate the corresponding frame, e.g.
with G54.
$P_BFRAME is identical to $P_CHBFRAME[0]. The system variable always has a valid default
value. If there is no channel-specific basic frame, an alarm is issued at read/write: "Frame:
Statement not permitted" is output on a read or write access.
Supplementary conditions
Writing of grinding frames through HMI/PLC
Only the grinding frames of the data management can be written from the HMI or the PLC user
program.
Basic frames can be read and written via part programs, via the OPI (only data management
frames and from the PLC.
Basic Functions
Function Manual, 01/2015, 6FC5397-0BP40-5BA2
K2: Axis Types, Coordinate Systems, Frames
10.5 Frames
733