Siemens SINUMERIK Series Function Manual page 38

A4: Digital and analog NCK I/Os for SINUMERIK 840D sl
1.2 Access via PLC
Read actual value
The analog values that are actually present at the hardware inputs are are sent to the PLC:
DB10 DBW194 ... 208 (actual value of the NCK analog input)
The possible influence of the PLC is ignored for the "actual value".
Disable input
Analog NCK inputs can be disabled individually from the PLC user program:
DB10 DBB146 (Disable analog NCK inputs)
In this case, they are set to a defined "0" inside the control.
Set input from PLC
The PLC can also specify a value for each analog NCK input:
DB10 DBB147 (analog value specification for NCK from the PLC)
As soon as this interface signal is set to "1", the setting value set by the PLC becomes active
for the corresponding analog input.
DB10 DBW148-162 (setpoint from the PLC for analog NCK input)
The analog value at the hardware input or the input disable is then inactive.
Weighting factor
The weighting factor can be used to adapt each individual NCK input to the various AD
converters (depending on the I/O module ) for reading in the part program:
MD10320 $MN_FASTIO_ANA_INPUT_WEIGHT[<n>]
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.
Note
Application for analog NCK inputs without hardware:
With a weighting factor of 32767, the digitized analog values for part program and PLC
access are identical. In this way, it is possible to use the associated input word for 1:1
communication between the part program and the PLC.
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Function Manual, 03/2013, 6FC5397-1BP40-3BA1
Extended Functions