User's Manual

Automation and Drives - SCE
T I A Training Document Page 8 of 25 Module
Status and fault/error displays
The CPU has the following LED displays:
Slot for the SIMATIC Micro Memory Card (MMC)
A SIMATIC Micro Memory Card (MMC) is used as a memory module for the CPU 31xC. The MMC
can be used as a load memory and as a transportable data carrier. The MMC must be plugged in
before the CPU can be operated because the CPUs 31xC do not have an integrated load memory.
Mode selector
The mode selector can be used to choose the current operating mode of the CPU. The mode
selector is designed as a toggle switch with 3 positions.
Positions of the mode selector
The positions of the mode selector are explained in the same sequence as they occur on the CPU:
Position Description Comments
RUN RUN mode The CPU is processing the user program
STOP STOP mode The CPU is not processing a user program
MRES Memory Reset Button position of the operating mode switch for a memory
reset of the CPU. A CPU memory reset requires a specific
operating sequence (refer to the Installation Manual,
Chapter Commissioning)
Foreword Notes
H
H
a
a
r
r
d
d
w
w
a
a
r
r
e
e
c
c
o
o
n
n
f
f
i
i
g
g
u
u
r
r
a
a
t
t
i
i
o
o
n
n STEP 7 program Testing
A5
Issue date: 02/2008 Programming the CPU 314C-2DP