Hello everyone, good evening~
Today, I will introduce how many communication methods are available for Siemens PLC.
Siemens PLC is a brand that many people frequently use, so today I will share the various ways to achieve communication with Siemens PLC in upper computer development. Here, we can explain from three aspects: serial communication, Ethernet communication, and OPC communication.
Siemens PLC supports serial communication, and both S7-200 and S7-200 Smart have serial ports integrated directly. However, from S7-1200 to S7-1500, these have gradually been removed. If needed, additional modules can be used to increase this capability. This phenomenon is actually an inevitable result of industrial development. The advantage of serial communication lies in its simplicity and low cost, but the disadvantages are also very obvious, namely low transmission efficiency. Siemens’ early serial communication mainly used Profibus DP communication, but the upper computer cannot directly communicate with Siemens PLC using Profibus DP. Therefore, the common serial communication schemes for Siemens PLC are as follows:
PPI Communication: PPI communication is only applicable to S7-200 and S7-200 Smart series PLCs, and other models do not support it.
Modbus RTU Master: Siemens PLC has good support for the Modbus protocol, where the PLC acts as Slave (i.e., subordinate), and the upper computer acts as Master (i.e., primary).
Modbus RTU Slave: Here, the PLC acts as Master (i.e., primary), and the upper computer acts as Slave (i.e., subordinate).
Siemens PLC communication is primarily based on Ethernet communication. Many people may know that Siemens has two main proprietary protocols: S7 protocol and Profinet bus. However, Profinet is a bus protocol, and as far as I know, C# cannot directly communicate with Siemens PLC using Profinet. Therefore, the common Ethernet communication schemes for Siemens PLC are as follows:
S7 Communication: Basically, from S7-200 to S7-1500, this can be achieved, and there are many open-source or commercial libraries available, including http://s7.net, pronodave, libnodave, sharp7, or one can create their own communication library.
Modbus TCP Server: Here, the PLC acts as Server (i.e., server), and the upper computer acts as Client (i.e., client).
Modbus TCP Client: Here, the PLC acts as Client (i.e., client), and the upper computer acts as Server (i.e., server).
Open Protocol Server: This refers to open TCP communication, where the PLC acts as TCP Server (i.e., server), and the upper computer acts as TCP Client (i.e., client).
Open Protocol Client: This refers to the PLC acting as TCP Client (i.e., client), and the upper computer acting as TCP Server (i.e., server).
OPC communication is a commonly used communication method in industrial control, mainly depending on the choice of OPC software and the selection of OPC DA and OPC UA. Therefore, the common OPC communication schemes for Siemens PLC are as follows:
PC Access Series: Siemens has developed PC-Access software for S7-200, and for S7-200 Smart, it provides PC-Access Smart software, which can directly achieve OPC DA communication through these software.
Simatic Net Series OPC DA: Simatic Net is Siemens’ main OPC software, supporting the entire Siemens series, primarily for OPC DA communication.
Simatic Net Series OPC UA: The new version of Simatic Net also begins to support OPC UA, which is primarily for OPC UA communication.
KepServer Series OPC DA: KepServer is also a commercially available OPC software, widely used domestically, and also supports the entire Siemens series, primarily for OPC DA communication.
Simatic Net Series OPC UA: The new version of KepServer also begins to support OPC UA, which is primarily for OPC UA communication.
