Siemens SINUMERIK 840D sl Function Manual page 1043

2.7.8 Symbolic programming of user program with interface DB
General
Note
The files NST_UDT.AWL and TM_UDT.AWL are supplied with the PLC basic program.
The compiled UDT blocks from these two files are stored in the CPU program of the basic
program.
A UDT is a data type defined by the user that can, for example, be assigned to a data block
generated in the CPU.
Symbolic names of virtually all the interface signals are defined in these UDT blocks.
The UDT numbers 2, 10, 11, 19, 21, 31, 71, 72, 73 are used.
The assignments have been made as follows:
UDT assignments
UDT
number
UDT2
UDT10
UDT11
UDT19
UDT21
UDT31
UDT71
UDT72
UDT3
To symbolically program the interface signals, the interface data blocks must first be
symbolically assigned using the symbol editor.
For example, symbol "AxisX" is assigned to operand DB31 with data type UDT31 in the
symbol file.
After this input, the STEP 7 program can be programmed in symbols for this interface.
Note
Programs generated with an earlier software version that utilize the interface DBs described
above can also be converted into symbol programs. To do so, however, a fully qualified
instruction is needed for data access in the earlier program (e.g., "U DB31.DBX 60.0" - this
command is converted to "AxisX.E_SpKA" when the symbols function is activated in the
editor).
Basic logic functions: PLC Basic program powerline (P3 pl)
Function Manual, 11/2006, 6FC5397-0BP10-2BA0
Assignment to interface DB
DB 2
DB10
DB11
DB19
DB21 to DB30
DB31 to DB61
DB71
DB72
DB73
2.7 Structure and functions of the basic program
Description
Alarms/messages
NCK signals
Mode group signals
HMI signals
Channel signal
Axis/spindle signals
Tool management: Load/unload locations
Tool management: Change in spindle
Tool management: Change in revolver
Detailed description
59