Siemens SIMATIC S7-300 - Manual (Page 51)

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SIMATIC S7-300 Getting Started for First Time Users
Getting Started, 04/2007, 6ZB5310-0NC02-0BA0
5.1 What is a program?
The program describes how the signals from the momentary contact switches
are logically linked to the outputs. The outputs of the CPU 312C will be used to
control the drive motor of the conveyor belt.
The program is part of the STEP 7 Lite project. Each program consists of organi-
zation blocks (OBs). The program for the conveyor is stored in OB1.
The program consists of networks. The networks, in turn, consist of normally-
closed and normally-open contacts and coils.