The maximum number of CP modules that can be slotted depends on
the CP type, the CPU type and the CPU-specific connection resources
that are available. All the details are available in the following
- Reference manual "Automation System S7-400 Module
Specifications" (Entry ID 1117740)
- Device manual "CPU 31xC and CPU 31x, Technical Data" (Entry ID:
- SIMATIC PLC S7-300, CPU Specifications CPU 312 IFM to CPU 318-2
DP (Entry ID 8860591).
In each case in the sections concerning the technical data under
the heading "Configuration" (number of CPs) and "Communication" or
"Communication functions" (connection resources).
The number of Cps for a point-to-point connection (PtP), for
example for the SIMATIC S7-400 CPUs, depends only on the number of
connection resources. It is limited to 8 for SIMATIC S7-300
You want to configure two Ethernet and 16
point-to-point connections in a SIMATIC S7-400 station.
- You need one CP443-1 per Ethernet connection.
- You need one CP441-2 for every two PtP connections.
You need resources for 20 connections. Must also use at
least one CPU 414-... that supports 32 connections (CPU 413...
only has 16 connection resources).