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Communication with SIMATIC PLC devices from the Siemens company

The following chapter informs about communication possibilities of the PROMOTIC system with the Simatic devices. The communication possibilities with the Simatic devices are relatively wide - it is possible to communicate by various communication protocols over various communication interfaces. The selection of the appropriate communication connection is both the technical question (required speed rate, response time to the technology status, wiring topology, etc.) and the economic question. Thus this documentation informs briefly only about the communication possibilities.
 

Simatic PLC communication types

Ethernet communication (S7 protocol, PROFINET, IE-Industrial Ethernet):

The S7 protocol is designed for transfering the data into the SCADA systems via Ethernet. The PROFINET protocol is used for communication between the PLCs and IO modules. Protokolem S7 lze komunikovat přes PROFINET konektor v PLC nebo v přídavných komunikačních modulech.

The Ethernet brings many advantages as speed, simple wire infrastructure, multiple stations on a single line, standardization, etc.

This communication type can be used for:

- PLCs that have the PROFINET connector built in the CPU (for example S7-1200, ET-200S, some types of S7-300 and S7-400)
- PLCs with additional Ethernet module (for example S7-200 + CP243-Ethernet, S7-300 + CP343-Ethernet, S7-400 + CP443-Ethernet)
- PLCs with NETlink converter (Ethernet <-> MPI/PROFIBUS converter) - see Communication with the NETLink PRO ETH converter
 
For this communication in the PROMOTIC system can be used:
- PmS7 - Driver for communication by S7-TCP/IP protocol - see the description below
- OPC server - see the description below

PROFIBUS communication:

PROFIBUS is a physical interface that cannot be directzly connected to the PC. The connection is managed by additional PROFIBUS PC card (or other additional HW).

 
For this communication in the PROMOTIC system can be used:
- PmS7 - Driver for communication by S7-TCP/IP protocol - see the description below. The driver can be used together with the Netlink converter (Ethernet <-> PROFIBUS converter).
- OPC server - see the description below

MPI communication:

The MPI (MPI-S7) interface is a "derivate" of the PROFIBUS-DP. The communication line is RS485, the speed rate is preset to 187.5kb/sec. The speed rate can be decreased to 19.2kb/sec and according to the device (CPU300, OP, CP6511) it can be even increased to 12Mb/sec.

 
For this communication in the PROMOTIC system can be used:
- PmS7 - Driver for communication by S7-TCP/IP protocol - see the description below. The driver can be used only together with the Netlink converter (Ethernet <-> MPI converter).
- OPC server - see the description below
- Communication using the PRODAVE or SoftNET-S7 libraries is considered obsolete and is not recommended.

PPI communication (Simatic S7-200):

The PPI interface is used for the Simatic S7-200 PLCs. It is a serial interface (so no special HW card is needed).

 
For this communication in the PROMOTIC system can be used:
- OPC server - see the description below
- The additional module CP243 can be used in order to enable the S7 protocol communication via the PmS7 driver - see the description below.
- The Simatic S7-200 CPU226 devices support also the communication interfaces MPI and PROFIBUS.
- The designer can implement simple ASCII protocol into the PLC S7-200 and then to use the PmChar - Driver for communication by user defined ASCII/BIN protocol in the PROMOTIC system. See the paragraph "Communication by ASCII protocol".

Communication by ASCII protocol:

For the communication with the SIMATIC devices that dispose of the ASCII serial communication interface it is necessary to know the description of the ASCII protocol on the Simatic side.

 
For this communication in the PROMOTIC system can be used:
Communication over PG port with Simatic S5:

The communication over the programming PG port on the Simatic. The communication is of the point-to-point type (1PC-1Simatic) over the serial link. For more Simatic devices it is possible to use the multi-port communication card on PC. The speed rate is 9600 Bd at the most. The communication is suitable for transfers not demanding quick answers.

 
For this communication in the PROMOTIC system can be used:
Communication by protocols 3964R, 3964 or RK512:

These protocols for the RS232 serial link support some Simatic devices directly and there is possible to purchase a communication module for these protocols for some PLC's.

 
For this communication in the PROMOTIC system can be used:
Communication by protocols SinecH1/SinecL1/SinecL2:

These protocol types are considered very obsolete.

 
For this communication in the PROMOTIC system can be used:
- OPC server - see the description below

Description of standard communication options between the PROMOTIC system and Simatic PLCs

Communication via the PmS7 PROMOTIC driver:

PmS7 - Driver for communication by S7-TCP/IP protocol communicates with the PLCs via the Ethernet protocol S7. If the PLC is equipped by the PROFINET connector, then the driver can be used (for example S7-1200, ET-200S, some types of S7-300 and S7-400).

PLCs without the PROFINET connector can be modified in order to enable the PROFINET connectivity, for example.

- add the Ethernet communication modules to the CPU (for example S7-200 + CP243-Ethernet, S7-300 + CP343-Ethernet, S7-400 + CP443-Ethernet)
- use the NETlink converter (Ethernet <-> MPI/PROFIBUS converter) - see Communication with the NETLink PRO ETH converter

 

For easy integration of this driver into the application it is handy to use:


Communication by OPC server:

Virtually all mentioned communication types can be executed via the OPC server. The PmOpcClient object is then used in the PROMOTIC application - See also Communication by OPC interface. There are many OPC server manufacturers. Below you can fing a short list.

 
- The Siemens company OPC server:

This OPC server is supplied by default with the PLC programming environment or it can be purchased in its software package SOFTNET, etc. The OPC server (or its variants) supports virtually all protocols required for the communication with the PLCs of the Simatic type (serial link, MPI, PROFIBUS, PROFINET, PPI, SinecH/L, etc.).

The description of the OPC server is outside the scope of this documentation. Just very brief overiew of the two basic ways of data items configuration:

- Symbols: the data items are defined in the OPC server under the selected symbolic name and the PROMOTIC system then uses these symbols in the "ItemID".

Example: "K3.CPU315(1).db20_Analog.aiEesaGJh" ...

- Objects: the data items are not defined in the OPC server. The "ItemID" item is used for defining the PLC data item addresses in the PROMOTIC system.

Example: "S7:[S7 connection_1]DB10,INT0,1", "S7:[S7 connection_2]DB4,X0,0,1", S7:[S7 connection_2]DB20,REAL42" ...

- The Softing company OPC server:

The Softing company (www.softing.com) is an OPC server manufacturer. The company also manufactures a HW converter NETlink PRO (Ethernet Gateway for MPI/PROFIBUS).

- Kepserver OPC server:

The Kepware company (www.kepware.com) is a manufacturer of universal OPC server, that is used not only for Simatic PLCs, but also a wide spectrum of other PLCs.

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