Chapter 1 Principles Manual VIPA CPU 21x
1-16 HB103E - Rev. 05/45
CPU 21x programs
The program that is present in every CPU is divided as follows:
• System routine
• User program
The system routine organizes all those functions and procedures of the
CPU that are not related to a specific control application.
This consists of all the functions that are required for the processing of a
specific control application. The operating modules provide the interfaces
to the system routines.
CPU 21x operands
The following operands are available for programming the CPU 21x:
• Process image and periphery
• Bit memory/marker
• Timers and counters
• Data blocks
The user program can quickly access the process image of the inputs and
outputs PII/PIO. You may manipulate the following types of data:
- individual bits
- bytes
- words
- double words
You may also gain direct access to peripheral modules via the bus from
your user program. The following types of data are available:
- bytes
- words
- blocks
Overview
System routine
User program
Overview
Process image
and periphery
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