Plc Machine Data - Siemens SINUMERIK 840D sl Function Manual

P3: Basic PLC program for SINUMERIK 840D sl
13.10 Structure and functions of the basic program
13.10.10

PLC machine data

General
The user has the option of storing PLC-specific machine data in the NCK. These machine data
can then be processed during power-up of the PLC (OB100). This enables, for example, user
options, machine expansion levels, machine configurations, etc., to be implemented.
The interface to read this data is in DB20. However, DB20 is set up by the basic program
during powerup only when user machine data are used, i.e., sum of GP parameters "UDInt",
"UDHex" and "UDReal" is greater than ZERO.
The sizes of the individual areas, and hence the total length of the DB20, is set by the following
PLC machine data:
MD14504 $MN_MAXNUM_USER_DATA_INT
MD14506 $MN_MAXNUM_USER_DATA_HEX
MD14508 $MN_MAXNUM_USER_DATA_FLOAT
These settings are specified to the user in the GP parameters "UDInt", "UDHex" and "UDReal".
The data is stored in the DB20 by the GP seamlessly in the sequence:
1. Integer MD
2. Hexa-fields MD
3. Real MD
The integer and real values are stored in DB20 in S7 format.
Hexadecimal data is stored in DB20 in the order in which they are input (use as bit arrays).
Figure 13-13 DB20
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Function Manual, 01/2015, 6FC5397-0BP40-5BA2
Basic Functions