Differences among various interfaces set in Step 7
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Mainly, what does PC internal (local) mean? Seeking guidance
PC internal (local) refers mainly to the network within software, with communication between STEP7 and PC STATION being a common example.
I see that other interfaces offer several options such as CP1623/MPI/PPI/PROFIBUS, etc. Aren’t these the interfaces used to connect a computer to the PLC’s CPU? Isn’t the PC internal interface also the connection interface between the computer and the CPU? ? Additionally, we have a set of redundant 400 PLCs; each computer is equipped with two CP1623 network cards. The network structure is shown in Figure 1. When the CP1623 interface is used, the engineer station can only connect to one main CPU, while the backup CPU cannot be connected (as shown in Figure 2). But after changing the interface mode to PC internal, the two CPUs were connected. Why is that? What is the fundamental difference between the PC internal interface and the CP1623? I hope you can give me some guidance. Thank you! ! !
The CP1623 interface is connected based on the actual MAC or IP address; it is not possible to connect two CPUs simultaneously, but the primary/secondary connection can be switched. The PC internal component is not connected directly to the CPU; it is connected through the PC STATRION, that is, via NET.
The PC internal function is somewhat similar to a named connection; it is used in Step 7’s NetPro to configure the communication methods between the PLC and the PC station (which can be DP, Ethernet, or even the original MPI, among others)