Siemens S7-300 appendix Mode selector switch, Reference, Power supply connection

Operating and display elements 2.1 Operating and display elements: CPU 31xC

Mode selector switch

Use the mode selector switch to set the CPU operating mode.

Table 2-1	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	Mode selector switch position with pushbutton function for CPU
	reset	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, CPU 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.

Differences between the CPUs

Table 2-2	Differences of the CPUs 31xC
Element		CPU	CPU	CPU	CPU	CPU	CPU
		312C	313C	313C-2 DP	313C-2 PtP	314C-2 DP	314C-2 PtP
9-pole DP		–	–	X	–	X	–
interface (X2)
15-pole PtP		–	–	–	X	–	X
interface (X2)
Digital inputs		10	24	16	16	24	24
Digital outputs		6	16	16	16	16	16
Analog inputs		–	4 + 1	–	–	4 + 1	4 + 1
Analog outputs		–	2	–	–	2	2
Technological		2 counters	3 counters	3 counters	3 counters	4 counters	4 counters
functions						1 channel for	1 channel
						positioning	for
							positioning

CPU 31xC and CPU 31x, Technical data	2-3
Manual, Edition 08/2004, A5E00105475-05