Siemens SINUMERIK 840Di Function Manual page 959

The M, S, T, H, D and F values sent by the NCK are output together with the accompanying
change signals to the CHANNEL DB interface via the auxiliary/G functions (see
documentation "Lists of SINUMERIK 840D, 810D"). The function value and the extended
address are transferred to the appropriate data word. The accompanying modification signal
is activated to 1 for one PLC cycle. When the modification signal is reset, the
acknowledgment is passed to the NCK. The acknowledgment of highspeed auxiliary
functions is given by the basic program immediately the basic program detects the auxiliary
function.
In addition to distribution of the auxiliary and G functions, selected signals are processed as
described below.
M decoder
M functions can be used to transfer both switching commands and fixed point values.
Decoded dynamic signals are output to the CHANNEL DB interface for standard M functions
(range M00 - M99); signal length = 1 cycle time.
G group decoders
In the case of G functions sent by the NCK, the related groups are decoded and the current
G number is entered in the corresponding interface byte of the CHANNEL DB, i.e., all active
G functions are entered in the channel DBs. The entered G functions are retained even after
the NC program has terminated or aborted.
Note
During system startup, all G group bytes are initialized with the value "0".
M, S, F distributor
The M, S, F, distributor is used to enter spindlespecific M words M(1...6)=[3,4,5], S words
and F words for axial feeds in the appropriate spindle and axis data blocks. The criterion for
distribution is the extended address, which is passed to the PLC for M words, S words and
axial F words.
MCP signal transmission
On the 840D, the MCP signals are transferred to the NCK via the serial bus (MPI) and from
there to the PLC. A function call from the basic program transfers the signals to the interface
of inputs and outputs specified by basic program parameters. The status signals for
controlling the LEDs on the machine control panel are passed in the opposite direction.
User messages
The acquisition and processing of the user error and operational messages is performed by
an FC in the basic program.
Power Line Basic PLC Program (P3)
Function Manual, 08/2005 Edition, 6FC5397-0BP10-0BA0
2.7 Structure and functions of the basic program
Detailed description
2-47