Siemens Simatic S7-300 CPU 31xC Series User Manual

Configuring
4.11 Planning subnets
S7-300, CPU 31xC and CPU 31x: Installation
Operating Instructions, Edition 08/2004, A5E00105492-05
4-41
Example: Maximum distances in the MPI subnet
The figure below shows you:
• a possible MPI subnet configuration
• maximum distances possible in an MPI subnet
• the principle of "Line extension" using RS 485 repeaters
PD[  P
PD[  P
3*
3*
56 
5HSHDWHU
PD[  P

6
&38
36
&38
03,DGGU

6
&38
36
&38
03,DGGU

6
&38
36
&38
03,DGGU
03,DGGU
23 
03,DGGU

6
&38
36
&38
03,DGGU
56 
5HSHDWHU
03,DGGU
23 

6
&38
36
&38
03,DGGU
03,DGGU
23 
03,DGGU







Key to numbers in the figure
(1) Terminating resistor enabled.
(2) PG connected by means of a stub cable for maintenance purposes

Siemens Simatic S7-300 CPU 31xC Series Specifications

General

Series	S7-300 CPU 31xC
Power Supply	24 V DC
Communication Interfaces	MPI, PROFIBUS DP
Programming Languages	LAD, STL, FBD, SCL
Operating Temperature	0°C to +60°C
Memory	48 KB - 512 KB
Dimensions	40 x 125 x 130 mm (varies by model)