Siemens SINUMERIK 840D sl Function Manual page 44

Digital and analog NCK I/Os (A4)
1.2 NCK I/O via PLC
2. The setting mask (DB10, DBB167) must be set to "1" for the analog output in question.
Unlike the overwrite mask, the current NCK value is not lost when a value is set in the setting
mask. As soon as the PLC sets "0" in the corresponding setting mask, the NCK value
becomes active again.
Note
The same setting value (DB10, DBB170 - 185) is used at the PLC interface for the overwrite
and setting masks.
Read setpoint
The current NCK value of the analog outputs can be read by the PLC user program:
DB10, DBB210 - 225 (setpoint of NCK analog output n)
Please note that this setpoint ignores disabling and the PLC setting mask. Therefore, the
setpoint can differ from the actual analog value at the hardware output (see fig.).
RESET/end of program
At the end of the program or on RESET, a specific default value can be assigned by the PLC
user program to every analog output in accordance with requirements, using the overwrite
mask, setting mask or disable signal.
POWER ON
After POWER ON the analog outputs are set to "0" in a defined manner. After booting, this can
be overwritten in the PLC user program according to the application, using the masks
described above.
Weighting factor
The weighting factor in general machine data
MD10330 $MN_FASTIO_ANA_OUTPUT_WEIGHT[hw].
can be used to adapt the analog NCK outputs to the different digital-to-analog converter
hardware variants for the purpose of programming in the part program (see fig.).
In this machine data, it is necessary to enter the value x that is to cause the analog output [n]
to be set to the maximum value or the value 32767 to be set for this output in the PLC
interface, if $A_OUTA[n] = x is programmed. The value set with system variable $A_OUTA[n]
then generates the corresponding voltage value at the analog output in millivolts.
Binary analog-value display
See "Analog-value representation of the NCK analog input/output values".
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Function Manual, 01/2008, 6FC5397-1BP10-3BA0
Extended Functions