Ethernet Communication Technology of Siemens S7-1200

1. Preparation before communication

First, create a new project and name it "Communication between s7-1200", as shown below:

Then configure the device and select the CPU 1214C DC/DC/RLY of s7-1200, version number 4.1, as shown below:

After opening the project, select the PLC_1 device view, select the "Properties" option below, then select "System and Clock Memory", and check the checkbox on the right that displays the Enable Clock Memory Byte, as shown below:

Then select the Ethernet port in the PLC_1 device and set the IP address of PLC_1 to 192.168.0.1 in the Ethernet address, as shown in the figure below:

Then copy and paste PLC_1 into PLC_2. Similarly, set the IP address of PLC_2 to 192.168.0.2 on the Ethernet port. The previous system and clock memory have been set up, so PLC_2 does not need to be set up again. The details are as follows:

In the device view, switch to the topology view, add the switch and PC respectively, and connect them as shown in the following figure.

At this point, the device settings before communication have been completed.

2. Programming

In the PLC_1 project, select the program block to open main (OB1), select "Open User Communication" in the communication item on the right, select the "TSEND_C" instruction and drag and drop it into main (OB1) to generate the background data block DB1, named: TSEND_C_DB. As shown in the figure below:

Select the command and the following configuration screen will pop up. Set it as shown below. Select TCP in the connection type. In the connection data row, select New in the drop-down menu to generate the screen shown below.

In the PLC_1 project, select the program block to open main (OB1), select "Open User Communication" in the communication item on the right, select the "TRCV_C" instruction and drag and drop it into main (OB1) to generate the background data block DB2, named: TRCV_C_DB, as shown below:

Select the command and the following configuration screen will pop up. Set it as shown below. Select TCP in the connection type. In the connection data line, select New in the drop-down menu to generate the following screen:

Then add a global data block named send, as shown below:

In the opened global data block name column, name it send, select array in the data type and set it to array[0....99]of string, as shown below:

Select send[DB5], right-click and select Properties, and uncheck the checkbox. As shown below:

The following are the settings for the instruction "TSEND_C":

Add a global data block and name it "receive", then open it and name it "receive", select array as the data type and set it to array[0....99]of string, as shown below:

Similarly, right-click receive[DB6] and select properties, and uncheck the checkboxes. As shown below:

The settings for the instruction "TRCV_C" are as follows:

At this point, the programming configuration of PLC_1 has been completed. The programming configuration settings of PLC_2 are similar to those of PLC_1. The basic settings are shown below:

The settings of the TSEND_C instruction in PLC_2 are configured as follows:

The settings of the TRCV_C instruction in PLC_2 are configured as follows:

The instructions TSEND_C and TRCV_C are set as follows:

At this point, the programming configuration of PLC_1 and PLC_2 has been completed.

Download Test

Download the program of PLC_1 to PLC

Download the PLC_2 program to the PLC

Add monitoring tables in PLC_1 and PLC_2, as shown below:

Start two PLCs and monitor them, enter the name and click Modify. The test results are as follows:

At this point, the communication is successful.