Data Management; Program Organization - Siemens SINUMERIK 808D Operating Instructions Manual

2.3

Data management

The data can be broken down into three areas:
● non-retentive data
● retentive data
● machine data for the PLC (this machine data is all active at POWER ON)
Most data, such as the process image, timers, and counters are non-retentive and are
cleared each time the control system is restarted.
For the retentive data, there is a data range of 1400 0000 -1400 0127. This location can be
used to save all the data which is to remain valid after POWER OFF/ON.
With the aid of the PLC-MD (see user interface), you can pre-assign your program with data
or parameterize various parts of the program.
2.4

Program organization

When programming the PLC, you must structure your program into finished program parts
(subroutines). The programming language for S7-200 offers you the capability to set up your
user program in a structured manner.
There are two types of programs:
● The main program
● The subroutine.
Eight levels of programming are possible.
PLC Subroutines Manual
Operating Instructions, 12/2012, 6FC5397-2EP10-0BA0
PLC Programming Tool
2.3 Data management
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