Siemens SINUMERIK 840D sl Function Manual page 36

A4: Digital and analog NCK I/Os
1.2 NCK I/O via PLC
Read actual value
The signal state of the digital NCK inputs is sent to the PLC:
DB10, DBB60 or DBB186 ... (actual value for digital NCK inputs)
The actual value reflects the actual state of the signal at the hardware input. The influence of
the PLC is, therefore, ignored in the actual value (see fig.).
RESET/POWER ON response
After POWER ON and RESET, the signal level at the respective input is passed on. If
necessary, the PLC user program can disable or set the individual inputs to "1" in a defined
manner as described above.
Applications
The program sequence can be controlled with conditional jump statements in the part
program as a function of an external-hardware-signal state.
For example, digital NCK inputs can be used for the following NC functions:
● Delete distance-to-go with positioning axes
● Fast program branching at the end of block
● Programmed read-in disable
● Several feedrates in one block
References:
/FBSY/ Function Manual; Synchronized Actions
The NCK inputs are assigned to the NC functions separately for each function and byte via
machine data. Multiple assignments of inputs are not monitored.
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Function Manual, 09/2009, 6FC5397-1BP20-0BA0
Extended Functions