Principle Of Operation Of The Programmable Controller; Functional Units; Schematic Representation Of The S5-115F - Siemens SIMATIC S5-115F User Manual

S5-115F Manual
2.2

Principle of Operation of the Programmable Controller

This section describes how the PC processes your program.
2.2.1

Functional Units

CPU
ACCUM
Timers,
counters,
Processor
flags
PII
Subunit A
Input modules
(digital / analog)
Function
modules
Program Memory
The control program is stored in the memory submodule ( 2.3.2) or in the internal RAM.
To safeguard against losing the program, dump it in an external EEPROM/EPROM memory sub-
module. In contrast to these memory submodules, the internal RAM or a RAM memory submodule
has the following characteristics:
• The memory contents can be changed quickly.
• User data can be stored and changed.
• When the power fails and there is no battery, the memory contents are lost.
In safety mode, the control program must be stored in the EEPROM/EPROM submodule. If no
memory submodule or another memory submodule is connected, the S5-115F switches auto-
matically into test mode.
EWA 4NEB 811 6148-02
Internal Memory
program submodule
memory (EPROM/
(RAM) EEPROM/
RAM)
Serial
inter-
face
PIQ
Parallel interface
I/O bus
Output modules
(digital / analog)
I/O modules
Figure 2-2. Schematic Representation of the S5-115F
Memory Internal
submodule program
(EPROM/ memory
EEPROM) (RAM)
Serial
inter-
face
Processor
PIQ
I/O bus
Output modules
(digital / analog)
Function
modules
Technical Description
CPU
ACCUM
Timers,
counters,
flags
PII
Subunit B
Input modules
(digital / analog)
I/O modules
2-3