Siemens Simatic S7-300 CPU 31xC Series User Manual

Configuring
4.11 Planning subnets
S7-300, CPU 31xC and CPU 31x: Installation
4-34 Operating Instructions, Edition 08/2004, A5E00105492-05
4.11.2.4 PROFIBUS DP interface
Availability
CPUs with “DP“ name suffix are equipped at least with a DP X2 interface.
The 315-2 PN/DP and 317 CPUs are equipped with an MPI/DP X1 interface. A CPU with
MPI/DP interface is supplied with default MPI configuration. You need to set DP mode in
STEP 7 if you want to use the DP interface.
Operating modes for CPUs with two DP interfaces
Table 4-16 Operating modes for CPUs with two DP interfaces
MPI/DP interface (X1) PROFIBUS DP interface (X2)
• MPI
• DP master
• DP slave
1
• not configured
• DP master
• DP slave
1
1
simultaneous operation of the DP slave on both interfaces is excluded
Properties
The PROFIBUS DP interface is mainly used to connect distributed I/O. PROFIBUS DP
allows you to create large subnets, for example.
The PROFIBUS DP interface can be set for operation in master or slave mode, and supports
transmission rates up to 12 Mbps.
The CPU broadcasts its bus parameters (transmission rate, for example) via the PROFIBUS
DP interface when master mode is set. A PG, for example, can thus receive the correct
parameters and automatically connect to a PROFIBUS subnet. You can disable this bus
parameter broadcast in you configuration.
Note
(for DP interface in slave mode only)
When you disable the Commissioning / Debug mode / Routing check box in the DP interface
properties dialog in STEP 7, all user-specific transmission rate settings will be ignored, and
the transmission rate of the master is automatically set instead. This disables the routing
function at this interface.

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)