Siemens SINUMERIK 840C - Manual (Page 596)

8 PLC Machine Data (PLC MD) 09.95
8.2 PLC MD for the operating system (system data)
Last active channel 8 1)
Default value Lower input limit Upper input limit Units
1 1 4 –
DB 60
DW 8
Last active spindle 9 1)
Default value Lower input limit Upper input limit Units
1 1 6 –
DB 60
DW 9
Last active axis 10 1)
Default value Lower input limit Upper input limit Units
3 1 30 –
DB 60
DW 10
These entries inform the PLC operating system of the numbers of the last channel, spindle
and axis.
See also PLC MD 6000, 6012 and 6016
Example:
PLC-MD 8 = 4, PLC MD 6000 = 0000 0111
Informs the PLC operating system that channels 1, 2 and 3 can be processed.
The PLC operating system processes DB10, DB11 and DB12 and transfers them to the NC-
PLC interface.
After each restart, the PLC system obtains the information required from the relevant NC
machine data and stores it in the data blocks DB60 and DB63, which means that
- the other PLC MD remain active
- the PLC processes only those channels, spindles and axes actually defined via NC MD
- any changes in the number of channels, spindles or axes will become effective only after a
PLC restart.
Last byte to reset in input image 11
Default value Lower input limit Upper input limit Units
127 64 127 –
DB 60
DW 11
Last byte to reset in output image 12
Default value Lower input limit Upper input limit Units
127 64 127 –
DB 60
DW 12
You can use this MD to specify the last input byte/output byte to be reset in the input
image/output image on a cold or warm restart. This means that the bytes not used by the
process peripherals can be utilized as additional retentive flag bytes.
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1) As from SW 3, these PLC MDs are irrelevant.
8–4 © Siemens AG 1992 All Rights Reserved 6FC5197- AA50
SINUMERIK 840C (IA)