Siemens SINUMERIK 840D sl Function Manual page 41

Disable input
The PLC user program is capable of disabling the NCK inputs individually using interface
signal DB10 DBB146 (disable analog NCK inputs).
In this case, they are set to "0" in a defined manner inside the control.
Set input from PLC
The PLC can also specify a value for each analog NCK input using interface signal
DB10 DBB147 (setting mask for analog NCK inputs) (see fig.).
As soon as this interface signal is set to "1", the setting value set by the PLC (DB10,
DBB148 to 163) becomes active for the corresponding analog input. The analog value at the
hardware input or the input disable is then inactive.
Read actual value
The analog values present at the hardware inputs are transferred to the PLC with the
following interface signal:
DB10 DBB194-209 (Actual value of the analog NCK input).
The possible influence of the PLC thus has no effect on the actual value (see figure).
RESET/POWER ON response
After POWER ON and RESET, the analog value at the input is passed on. If necessary, the
PLC user program can manipulate the individual analog NCK inputs via the PLC user
program, as described above.
Weighting factor
The weighting factor in general machine data can be used to adapt the analog NCK inputs to
different analog-to-digital converter hardware variants for the purpose of reading in the part
program (see figure):
MD10320 $MN_FASTIO_ANA_INPUT_WEIGHT[hw]
In this machine data, it is necessary to enter the value x that is to be read in the part program
with the system variable $A_INA[n], if the corresponding analog input [n] is set to the
maximum value or if the value 32767 is set for this input via the PLC interface. The voltage
level at the analog input is then read with system variable $A_INA[n] as a numerical value
with the unit millivolts.
Binary analog-value display
See "Analog-value representation of the NCK analog input/output values".
Extended Functions
Function Manual, 03/2009, 6FC5397-1BP10-4BA0
Digital and Analog NCK I/Os (A4)
NCK I/O via PLC
41