Siemens S7-1200 System Manual page 132

PLC concepts
4.5 Using a memory card
Using a program card as the load memory for your CPU
Risks associated with inserting a program card
Verify that the CPU is not actively running a process before inserting the memory card.
Inserting a memory card will cause the CPU to go to STOP mode, which could affect the
operation of an online process or machine. Unexpected operation of a process or machine
could result in death or injury to personnel and/or property damage.
Before inserting a memory card, always ensure that the CPU is offline and in a safe state.
To use a program card with your CPU, follow these steps:
1. Insert the program card into the CPU. If the CPU is in RUN mode, the CPU goes to STOP
mode. The maintenance (MAINT) LED flashes to indicate that the memory card needs to
be evaluated.
2. Power-cycle the CPU to evaluate the memory card. Alternative methods for rebooting the
CPU are to perform either a STOP-to-RUN transition or a memory reset (MRES) from
STEP 7.
3. After the CPU reboots and evaluates the program card, the CPU erases the internal load
memory of the CPU.
The CPU then goes to the start-up mode (RUN or STOP) that you configured for the CPU.
The program card must remain in the CPU. Removing the program card leaves the CPU with
no program in internal load memory.
Risks associated with removing a program card
If you remove the program card, the CPU loses its external load memory and generates an
error. The CPU goes to STOP mode and flashes the error LED.
Control devices can fail in an unsafe condition, resulting in unexpected operation of
controlled equipment. Such unexpected operations could result in death or serious injury to
personnel, and/or damage to equipment.
Do not remove the program card without understanding that you are removing the program
from CPU.
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WARNING
WARNING
S7-1200 Programmable controller
System Manual, 03/2014, A5E02486680-AG