Siemens Simatic S7-200 CPU 210 System Manual page 34

Installing and Using the STEP 7-Micro/WIN Version 2.0 Software
As shown in Figure 2-10, the CPU 210 performs the following tasks after you turn the power
on when a memory cartridge is installed in the CPU 210:
The M, T, and Q areas of memory are cleared.
The current values for the counters (which are stored in the permanent memory) are
cleared. (The current values for the counters are erased only when the memory cartridge
is installed in the CPU 210. If a memory cartridge is not installed, the current values are
retained.)
The user program is copied from the memory cartridge to the permanent EEPROM
memory.
Always remove the memory cartridge from the CPU 210 after the program has been
installed.
Note
Turning the power on with a blank memory cartridge in the CPU 210 causes an error and
lights the error LED. Any program stored in the permanent EEPROM is not affected or
overwritten. To correct the error condition, remove the memory cartridge and cycle the
power again.
When a valid program is installed, the CPU 210 automatically goes to RUN mode when
power is applied.
As your program runs, the CPU 210 updates the values stored in the RAM memory (the
values stored in M memory, the current values for the four counters, and the current values
for the four timers).
When you turn the power off, the CPU 210 saves the current values of the four counters to
the permanent EEPROM memory. The other values stored in RAM (such as M memory,
current values for the timers, and the copy of the user program) are cleared.
Unless a memory cartridge is installed in the CPU 210, the current values for the counters
are retentive. The current values for the counters are automatically restored to the RAM
memory when you turn power on for the CPU 210 (with no memory cartridge installed).
Figure 2-10 Loading a Program with the Memory Cartridge
2-12
When the memory cartridge is installed in the CPU 210,
turning on the power copies the user program to the
Memory
permanent memory
Cartridge
User Program
Counter values
Current values
of the counters
EEPROM Memory (Permanent)
RAM Memory
M memory
Current values
of the counters
Current values
of the timers
S7-200 Programmable Controller, CPU 210
C79000-G7076-C235-01