Siemens SIMATIC S7-300 Hardware And Installation Manual page 25

Components
CPU
Accessory:
Front connectors (for CPUs with
integrated peripherals)
Signal modules (SM)
(Digital input modules, digital
output modules, digital I/O
modules, analog input modules,
analog output modules, analog
I/O modules)
Accessory:
Front connectors
Function modules (FM)
Accessory:
Front connectors
Communication processor (CP).
Accessory:
Connecting cable
S7-300 Programmable Controller Hardware and Installation
A5E00105492-02
Function
This runs the user program,
provides a 5 V supply to the S7-
300 backplane bus and
communicates with other MPI
network nodes via the MPI
interface.
Additional properties of specific
CPUs:
•
DP master in a PROFIBUS
subnet
•
DP slave in a PROFIBUS
subnet
•
Technological functions
•
Point-to-point connection
•
The CPUs have different external
appearance.
Different mode selector switches:
The 312 IFM – 318-2 DP CPUs
have a key switch, while the
CPUs 312C to 314C-2 PtP/DP
have a slide switch.
Another distinguishing features is
that the CPU has either an MC or
an MMC.
They match different process
signal levels to the S7-300.
These perform time-critical and
memory-intensive process signal
processing tasks, such as
positioning or regulation.
This performs communication for
the CPU, e.g. CP 342-5 DP
connection to PROFIBUS DP
S7-300 modules
Illustration
SIEMENS
CPUs 312C to 314C-2 PtP/ DP
CPUs 312 IFM to 318-2 DP
SIEMENS
CPU 312, 314 and 315-2 DP
4-3