Siemens SINUMERIK 840D sl Function Manual page 38

A4: Digital and analog NCK I/Os
1.2 NCK I/O via PLC
Disable output
The PLC user program is capable of disabling the digital NCK outputs individually with
interface signal
DB10, DBB4 or DBB130 ... (disable digital NCK outputs).
In this case, the "0" signal is output at the hardware output (see fig.).
Overwrite mask
Every output that can be set by the NC part program can be overwritten from the PLC using
the overwrite mask. The previous NCK value is then lost (see fig.).
The following routine has to be carried out to overwrite the NCK value from the PLC:
1. The relevant PLC interface output has to be set to the required signal status:
2. The setting value becomes the new NCK value when the overwrite mask for the relevant
Setting mask
Furthermore, a PLC setting for each output can determine whether the current NCK value
(e.g., as specified by the NC part program) or the PLC value specified via the setting mask
(DB10, DBB7 or DBB133 ...) should be sent to the hardware output (see fig.).
The following routine has to be carried out to define the PLC value:
1. The output in question must be preset with the required signal state at the PLC interface
2. The setting mask must be set to "1" for the output in question.
Unlike the overwrite mask, the NCK value is not lost when a value is set in the setting mask.
As soon as the PLC sets "0" in the setting mask, the NCK value becomes active again.
Note
The same setting value (DB10, DBB6) is used at the PLC interface for the overwrite and
setting masks. Therefore, an identical output signal state is the result if the signal state is
changed simultaneously in the overwrite and setting maska.
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DB10 DBB6 or DBB132 ... (Setting value by PLC of digital NCK outputs)
output (DB10, DBB5, or DBB131 ...) is activated (signal transition 0 → 1). This value
remains operative until a new NCK value is programmed (by the PLC or from the NC part
program).
DB10, DBB6 (PLC setting value for digital NCK outputs).
Function Manual, 09/2009, 6FC5397-1BP20-0BA0
Extended Functions