Operation Of The 40 And 50 Series Basic Units; Functional Diagram - ABB 07CR41 Operating Manual

1.3

Operation of the 40 and 50 series basic units

1.3.1

Functional diagram

3
The memory of the 40 and 50 series is composed of two distinct areas:
- A RAM memory where the user program and data is loaded
- A Flash EPROM memory which contains:
- a backup of the user program with the program constants,
- the configuration data
- and the system program, which is protected against access by the user program.
A built-in battery (only in 50 series) also enables the backup of internal variables.
The system program comprises a set of universal functions designed to cover all applications
and ensure all the basic PLC functions. The user program is developed with the
907 PC331 R402 programming and test software. After being translated into instructions which
can be understood by the basic unit, the program is loaded in RUN or STOP mode into the
RAM and then saved to the Flash EPROM. This means that each time the program is loaded,
the user program saved in the Flash EPROM is copied to the RAM for processing by the mi-
croprocessor (Figure 3).
The structure of the system program memory, the user program, the inputs/outputs and inter-
nal variables are described in the appendix.
PC
Program
transmission
Figure 3: Functional diagram of a basic unit
Introduction
BASIC UNIT
CPU
ASIC
UART
Isolated
RS232/485
connection
1 – 4
At program
call-up
RAM Flash
Advant Controller AC 31 / Issued: 01.99