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Siemens S7 PLC is a PROFIBUS device that can communicate to a PROFIBUS network through MPI protocol using PROFIBUS interface card, such as an Applicom board. It can also be configured for direct connection with a PC using HMI Adapter, a device that translates MPI protocol into RS-232 protocol. To connect a Siemens S7 PLC to a PC, connect the HMI Adapter to the MPI port on the PLC, and connect the adaptor to the PC serial port using a null-modem serial cable.
Note Make sure you are using a null modem serial cable, otherwise it will not work.
This example was created using Lookout 4.5.1, Lookout Protocol Drivers 4.5, and a Siemens S7 CPU-313 PLC with HMI Adapter (Siemens - PC Adapter).
1. Launch Lookout or Lookout Protocol Drivers, create a new process, and create a new object by selecting Object >> Create.
2. Select the S7_HMI object from the object list.
3. Configure the object properties using the exact communication settings from the proprietary software (the image below corresponds to a specific PLC configuration, your settings may be different). Click OK when you are done.
4. The PLC is now configured in Lookout or Lookout Protocol Drivers and you can start accessing the PLC register. Before accessing any register, it is better to know the name and type of data members available for this particular object.