Siemens S7-300 appendix Slot for the Simatic Micro Memory Card MMC

Operating and display elements

2.2 Operating and display elements: CPU 31x

Slot for the SIMATIC Micro Memory Card (MMC)

A SIMATIC Micro Memory Card (MMC) is used as memory module. You can use MMCs as load memory and as portable storage medium.

Note

These CPUs do not have an integrated load memory and thus require an MMC for operation.

Mode selector switch

The mode selector switch is used to set the CPU operating mode.

Table 2-3	Positions of the mode selector switch
Position	Meaning	Description
RUN	RUN mode	The CPU executes the user program.
STOP	STOP mode	The CPU does not execute a user program.
MRES	CPU memory reset	Mode selector switch position with pushbutton function for CPU
		memory reset. A CPU memory reset by means of mode
		selector switch requires a specific sequence of operation.

Reference

•CPU operating modes: STEP 7 Online Help.

•Information on CPU memory reset: Operating instructions CPU 31xC and CPU31x, Commissioning, Commissioning Modules, CP Memory Reset by means of Mode Selector Switch

•Evaluation of the LEDs upon error or diagnostic event: Operating Instructions CPU 31xC and CPU 31x, Test Functions, Diagnostics and Troubleshooting, Diagnostics with the help of Status and Error LEDs

Power supply connection

Each CPU is equipped with a double-pole power supply socket. The connector with screw terminals is inserted into this socket when the CPU is delivered.

2-6	CPU 31xC and CPU 31x, Technical data
	Manual, Edition 08/2004, A5E00105475-05