Siemens SIMATIC S7-300 Series Reference Manual

Also see for Simatic S7-300: User manual Getting started Technical data Operating instructions Installation manual

Contents

CPU Function, depending on CPU and STEP 7 Version4-3PLC S7-300, CPU Specifications CPU 312 IFM to CPU 318-2 DPA5E00111190-01System ID (only CPU 318-2)In the object properties of the ”General” tab, you can assign a system ID whenconfiguring your CPU. This ID can be evaluated in the CPU user program (alsorefer to the STEP 7 Online Help relating to the “General” tab).MPI AddressingCPU 318-2 CPUs 312IFM to 316-2DPThe CPU addresses the MPI nodes within itsconfiguration (FM/CP) via the module startaddress.If FM/CP are in the central configuration of anS7–300 with their own MPI address, the CPU formsits own communication bus (via the backplane bus)with the FM/CP, separate from the other subnets.The MPI address of the FM/CP is no longerrelevant for the nodes of other subnets.Communication to the FM/CP takes place via theCPU MPI address.The CPUs address the MPI nodes within theirconfiguration via the MPI address.If FM/CP are in the central configuration of anS7–300 with their own MPI address, the FM/CPand CPU MPI nodes are in the same CPU subnet.Your S7-300 structure includes an FM/CP addressed via MPI. You want to replacethe CPU 312 IFM ... 316 with a CPU 318-2. An example is shown in Figure 4-1,Page 4-4.