说明：  西门子仿真编程软件S7-PLCSIM V5.4，用于S7-300/400系列PLC程序的仿真
(S7-PLCSIM V5.4 offers the following new features with this release: DP, Industrial Ethernet and PC Internal connection types supported in addition to MPI Formerly, S7-PLCSIM used a default connection of MPI, address 2. With S7-PLCSIM V5.4, you can browse STEP 7 projects and select a networked node for establishing a simulation connection. S7-PLCSIM simulates the CPU of the selected node, all nodes that belong to that CPU, and the subnet of the selected node. Increased number of blocks supported for simulation S7-PLCSIM supports a set of OBs, SFBs, and SFCs as described in the electronic manual and online help. Of these, some are NOPs that is, they do not perform any operation. With S7-PLCSIM V5.4, the number of blocks that are not NOPs has increased.)