P3: Basic PLC Program for SINUMERIK 840D sl
13.8 Structure and functions of the basic program
Basic Functions
878 Function Manual, 09/2011, 6FC5397-0BP40-2BA0
Control/Status signals
A shared feature of the control and status signals is that they are bit fields. The basic program updates them at
the start of OB1.
The signals can be subdivided into the following groups:
• General signals
• Mode group-specific signals (such as mode types)
• Channelspecific signals (such as program and feed modifications)
• Axis- and spindlespecific signals (such as feed disable)
Auxiliary and G functions
The auxiliary and G functions have the following characteristics:
• Transfer to the PLC is blocksynchronous (referred to a parts program block)
• Transfer is acknowledgedriven.
• The acknowledgment times have an immediate effect on the execution time of NC blocks containing auxiliary
functions requiring acknowledgment.
The value range is presented in the table below:
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 List Manual). 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.
Function Structure Range of values Data type
1. Value 2. Value 1. Value 2. Value 1. Value 2. Value
G function G function
255
1)
Byte
M word M group M word 99 99.999.999 Word DWord
S word Spindle no. S word 6 Floating
point
2)
Word DWord
T word Magazine
no.
T word 99 65535 Word Word
D word - D word 99 255 Byte Byte
H word H group H word 99 Floating
point
Word DWord
F word Axis No. F word 18 Floating
point
Word DWord
1)
relative number, transferred for each G group
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