Q: Is it equivalent to the role of an MPI cable?
A: There seems to be some confusion here between the dedicated network connector and the Siemens communication protocol. These are two distinct concepts. The DP bus connector with a programming port is just a physical network connector, while MPI is a communication protocol. In most PLC systems, the MPI port is typically equipped with a DP bus connector for uploading, downloading, or monitoring the PLC program.
Firstly, the physical layer for PPI, MPI, and PROFIBUS-DP communication in Siemens PLCs all use RS-485 technology. This means that the same type of communication cable and special connectors can be used across these protocols. Siemens provides two types of network connectors: a standard one and a programming port version. The programming port allows a programming device or PC to connect to the network without interfering with existing network operations.
MPI is a proprietary protocol developed by Siemens specifically for PLCs. That’s why Siemens PLCs come with an MPI interface. Through this interface, a PG/PC can access all intelligent modules connected to the hardware stations on the network.
On the other hand, the DP bus connector with a programming port is mainly a physical connector that includes a programming port. It can function as a standard network connector between DP slaves, but it's more commonly used for connecting to the MPI port on the PLC for tasks like uploading or downloading programs and monitoring the PLC.
If you open the hardware configuration interface and double-click the corresponding CPU, its properties will appear. Under the "Communication" section, the PLC operating system automatically reserves a connection resource for the PG or PC, allowing it to connect to the PLC at any time. Importantly, the MPI interface does not interfere with normal network communication.
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