Siemens SINUMERIK 840D sl Function Manual page 32

Digital and Analog NCK I/Os (A4)
NCK I/O via PLC
The processing mode is selected for individual modules by means of general machine data:
MD10384 $MN_HW_CLOCKED_MODULE_MASK[tb]
[tb] = Index for terminal block (0 to 1)
In synchronous processing mode, one of the following clock rates can be selected
(MD10380 $MN_HW_UPDATE_RATE_FASTIO[tb]):
● Synchronous inputs/outputs in position-control cycle (default setting)
● Synchronous inputs/outputs in interpolation cycle
It is possible to define a lead time in microseconds for the clocked NCK I/Os in general
machine data:
MD10382 $MN_HW_LEAD_TIME_FASTIO[tb].
This makes it possible to consider the conversion time of the analog-to-digital converter, for
example, so that the digitized input value is available at the cycle time.
The defined clock rate or rate time applies to all isochronous I/O modules of the terminal
block addressed with [tb].
Monitoring
The following functional monitors are provided for external I/Os on the SINUMERIK 840D:
● During booting:
● During cyclic operation:
In the event of a fault, NC-Ready is canceled and an alarm is output.
Response to faults
In case of malfunction the digital and analog NCK outputs
are switched to "safe" status (0 V at output), in the event of faults (e.g. NC-Ready = 0) in the
NCU or power failures.
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– Check whether the arrangement of components of the I/O modules in the terminal
blocks matches the MD assignments.
– Sign-of-life monitoring in interpolation cycles
– Module monitoring in interpolation cycles
– Temperature monitoring
Function Manual, 03/2009, 6FC5397-1BP10-4BA0
Extended Functions